38 circulatory and€¦ · systems play major roles in these functions. the circulatory system,...

Chapter 38 • Circulatory and Respiratory Systems 871

Opening ActivityHave one student take the restingpulse of a volunteer, and haveanother student determine the vol-unteer’s breathing rate. Have thevolunteer do jumping jacks for 1 minute and then re-measure andrecord his or her pulse and breath-ing rates. Ask students: How do thepulse and breathing rate vary afterexercise? (Both increase after exer-cise.) Why would the pulse rateincrease during exercise? (Activemuscles require more nutrients andoxygen than inactive ones.) Whydoes the breathing rate increaseduring exercise? (Sensors in the bodydetect low oxygen levels and highcarbon dioxide levels, and stimulatethe respiratory center which in turnstimulates more rapid breathing.)

• Vocabulary Worksheets

• Concept Mapping

Chapter Resource File

Answers

1. Homeostasis is the mainte-nance of a nearly stable inter-nal environment in the body.

2. Diffusion is the movement ofsubstances from an area wherethey are more concentrated toan area where they are lessconcentrated. Osmosis is themovement of water from anarea in which there is lesssolute to an area where there ismore solute.

3. Oxygen is needed in order forelectrons to continue movingalong the electron transportchain and generating ATP.Oxygen picks up the electronsat the end of the electron trans-port chain.

4. Cardiac muscle is made up ofinterconnecting muscle cellsthat contract and are underinvoluntary control. Smoothmuscle is made up of musclecells that contract and areunder involuntary control.Epithelial tissue is generallymade up of flat, thin cells thatline organs or cover body sur-faces. Connective tissue ismade up of cells contained inan intercellular matrix thatprovide support, protect thebody, and insulate the body.

Quick Review

Answers

Students probably have formed operational

definitions of many of the words in this chap-

ter, such as vein, artery, red blood cell, blood

pressure, heart attack, and diaphragm. Have

pairs of students check each other’s answers

when they are finished.

Reading Activity

Looking AheadQuick ReviewAnswer the following without referring to

earlier sections of your book.

1. Define homeostasis. (Chapter 1, Section 1)

2. Define the terms diffusion and osmosis.

(Chapter 4, Section 1)

3. Summarize the role of oxygen in aerobic

respiration. (Chapter 5, Section 3)

4. Describe cardiac muscle, smooth muscle,

epithelial tissue, and connective tissue.

(Chapter 37, Section 1)

Did you have difficulty? For help, review the

sections indicated.

Section 1

The Circulatory SystemTransport and Distribution

Blood Vessels

Components of Blood

Section 2

The HeartA Muscular Pump

Circulation of Blood

Section 3

The Respiratory SystemGas Exchange

Breathing

Gas Transport

Respiratory Diseases

www.scilinks.orgNational Science Teachers Association sciLINKS Internet

resources are located throughout this chapter.

Reading ActivityBefore you begin to read this chapter, write

down all of the key words for each of the three

sections in the chapter. Then, write a definition

next to each word that you have heard of.

As you read the chapter, write definitions next

to the words that you did not previously know,

and modify as needed any definitions of words

you knew.

Sports that require running, such as soccer, provide

aerobic exercise. Aerobic exercise increases the

body’s use of oxygen and causes breathing

rate and heart rate to increase.

Circulatory andRespiratorySystems

CHAPTER

38

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Copyright © by Holt, Rinehart and Winston. All rights reserved.

OverviewBefore beginning this sectionreview with your students theobjectives listed in the StudentEdition. Students will be able todescribe the structure of the heartand blood vessels (cardiovascularsystem), how these structures func-tion in transporting materials allaround the body, and how materi-als move into and out of the bloodvessels. Students will also describethe structure of the lymphatic sys-tem, how it picks up excess fluidsin body tissues and returns them tothe cardiovascular system, and therole of the lymphatic system inimmunity.

Ask students the following ques-tion: Is blood a liquid or a solid?Then, have them write down whatthey think is found in blood. (Manystudents will know that plasma(liquid) and blood cells (solid) are in blood. Blood also contains water,hormones, antibodies, nutrients,oxygen, carbon dioxide, salts, ions,wastes, and other materials.)

ActivityCirculatory Function Ask stu-dents to name possible functions ofthe circulatory system, and writethem on the board. (The circulatorysystem carries oxygen, carbon diox-ide, nutrients, hormones, cells of theimmune system, wastes, and othermaterials; and it is involved in regu-lating body temperature.) VerbalLS

GENERAL

MotivateMotivate

Bellringer

FocusFocus

Section 1

872 Chapter 38 • Circulatory and Respiratory Systems

Transparencies

TR Bellringer

TR J22 Cardiovascular System

TR J21 Blood Vessels

• Directed Reading

• Active Reading

• Data Sheet for Quick Lab GENERAL

GENERAL


• Reading Organizers

• Reading Strategies

• Occupational Application WorksheetBlood-Bank Technologist GENERAL

Planner CD-ROM

Section 1 The Circulatory System

Transport and Distribution Regardless of your activities—whether you are roller-blading,

swimming, singing, reading, or just sleeping—your body transports

nutrients, hormones, and gases, and it gets rid of wastes. Two body

systems play major roles in these functions. The circulatory system,

which includes the cardiovascular and lymphatic systems, trans-

ports these materials to different parts of the body. The respiratory

system exchanges gases with the environment—it takes in oxygen,

O2, and releases carbon dioxide, CO2.

The human , shown in Figure 1, functions

like a network of highways. The cardiovascular system connects the

muscles and organs of the body through an extensive system of

vessels that transport blood, a mixture of specialized cells and fluid.

The heart, a muscular pump, propels blood through the blood vessels.

Different kinds of molecules move through the cardiovascular

system:

1. Nutrients from digested food are transported to all cells in the

body through the blood vessels of the cardiovascular system.

2. Oxygen from the lungs, where the oxygen is taken in, is trans-

ported to all cells through blood vessels.

3. Metabolic wastes, such as carbon

dioxide, are transported through

blood vessels to the organs and

tissues that excrete them.

4. Hormones, substances which

help coordinate many activities

of the body, are transported

through blood vessels.

5. The cardiovascular system also

distributes heat more or less

evenly in order to maintain a

constant body temperature. For

example, in a warm environ-

ment, blood vessels in the skin

relax to allow more heat to leave

the body. In a cold environment,

blood vessels constrict, conserv-

ing heat by diverting blood to

deeper tissues. This diversion of

blood prevents heat from escap-

ing the body.

cardiovascular system

Objectives

● List five types of molecules

that are transported by the

cardiovascular system.

● Differentiate between

arteries, capillaries,

and veins.

● Relate the function of the

lymphatic system to the func-

tions of the cardiovascular

and immune systems.

● Relate each component of

blood to its function.

● Summarize how a person’s

blood type is determined.

Key Terms

cardiovascular system

artery

capillary

vein

valve

lymphatic system

plasma

red blood cell

anemia

white blood cell

platelet

ABO blood group system

Rh factor

Figure 1 Blood vessels,

blood, and a heart.

The cardiovascular system

transports materials

throughout the body and

distributes heat.

Cardiovascular System

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Teaching TipBlood-Brain Barrier Providestudents with the information con-tained in the Medicine Connectionfeature at the bottom of this page.Point out that, while the exclusionof most chemicals from the brain isadvantageous, it can be a seriousproblem when physicians try totreat disorders involving the brainand brain function. A major diffi-culty in treating brain tumors, forexample, is that most of the chemi-cal agents used to treat cancer cannot reach targets across theblood-brain barrier. The blood-brain barrier also prevents most ofthe anti-retroviral drugs now usedto treat AIDS from entering thecentral nervous system. In additionto infecting cells of the immune system, HIV directly infects cellswithin the brain itself and theblood-brain barrier prevents thesedrugs from battling HIV-infectedcells in the brain.

Using the Figure Direct students’ attention toFigure 2. Tell students that veinshave a much wider inside diameterthan arteries. This difference relatesto the differences in function ofthese two kinds of vessels. Arteriestransport blood away from theheart under high pressure and forceit into tiny capillaries. Veins trans-port blood under low pressure backto the heart. Point out the thickermuscular wall of the artery in thefigure. Also point out the valvelocated in the vein.

Interactive Reading AssignChapter 38 of the Holt BiologyGuided Audio CD Program to helpstudents achieve greater success inreading the chapter.

SKILL

BUILDER

READINGREADING

GENERAL

TeachTeach


MEDICINEMEDICINECONNECTIONCONNECTION

actively transported into the fluid surround-ing the brain cells.

This barrier’s most important function is toprovide neurons with the exact amount of glu-cose they need. If glucose levels go up or downeven slightly, neurons can begin to malfunc-tion. The blood-brain barrier also maintains aprecise balance of necessary ions within thebrain. The connections between neurons aresensitive to ion concentrations, and evenminor changes can affect nerve transmission.

The blood-brain barrier is made up of a sin-gle layer of endothelial cells that are tightlypacked together and line the inner surfaces ofcapillaries in the brain. Endothelial cells inother parts of the body have gaps betweenthem through which water, ions, molecules,and even some blood cells can easily diffuse.Water is the only constituent of the bloodthat can diffuse freely across the blood-brainbarrier. Substances required by the brain,such as glucose and other nutrients, are

Blood VesselsBlood circulates through the body through a network of vessels.

(AHRT uh reez), shown in Figure 2, are blood vessels that

carry blood away from the heart. Blood passes from the arteries

into a network of smaller arteries called arterioles (ahr TIHR ee

ohls). Eventually, blood is pushed through to the capillaries.

are tiny blood vessels that allow the exchange of

gases, nutrients, hormones, and other molecules in the blood. The

molecules are exchanged with the cells of the body. From the capil-

laries, the blood flows into small vessels called venules (VEHN

yools). From the venules, blood empties into larger vessels called

veins (vaynz). are blood vessels that carry the blood back to

the heart.

Arteries With each contraction, the heart forcefully ejects blood into arteries.

To accommodate each forceful pulse of blood, an artery’s wall

expands and then returns to its original size. Elastic fibers in the

walls of arteries allow arteries to expand.

The wall of an artery is made up of three layers of tissue, as

shown in Figure 2. The innermost layer is a thin layer of epithelial

tissue called the endothelium. The endothelium is made up of a

single layer of cells. Surrounding the endothelium is a layer of

smooth muscle tissue with elastic fibers. Finally, a protective layer

of connective tissue with elastic fibers wraps around the smooth

muscle tissue. Just as a balloon expands when you blow more air

into it, the elastic artery expands when blood is pumped into it.

Veins

Capillaries

Arteries

Endothelium

Smooth muscle

Connective tissue

Arteriole(connects arteries

to capillaries)

Capillaries(exchange gases, nutrients,

wastes, and hormones)

Venule(connects veinsto capillaries)

Artery(carries blood away from the heart)

Vein(returns blood to the heart)

Reviewing Information

You can remember that

arteries take blood away

from the heart and veins

carry blood toward the heart

by remembering the letter a

at the beginning of the word

artery and at the beginning

of the word away.

Magnification: 1,1503

Blood vessels transport blood and allow for the exchange of substances.

Figure 2 Blood vessels

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Teaching TipA Closed System Remind stu-dents that the circulation of blood inhumans is a closed system, one inwhich the blood does not leave theheart and blood vessels. Other mate-rials, however, such as nutrients,oxygen, certain blood cells, water,and wastes, are transferred betweenthe blood and other tissues by pass-ing through the walls of the smallestblood vessels, the capillaries.

DemonstrationShow the class a picture of a personin a hospital bed. Ask why hospitalworkers try to get patients to walk,if only for a few minutes each day.(Students should recognize that musclemovements squeeze the walls of veins,thus preventing blood from accumu-lating and clotting in parts of the bodysuch as the legs. Other methods ofenhancing circulation used in hospitalsinclude special compression stockingsand pumps that promote blood flowthrough the lower extremities.) Askstudents what happens to them ifthey stand in one place for a longperiod of time, as during a schoolassembly or concert. (Most will haveexperience some discomfort and possi-bly dizziness if they have stood for along time.) Tell students that they canhelp move blood back to the heartwhile standing if they repeatedlybend their legs at the knees.

Teach, continuedTeach, continued


Remind students that as the circulatory system distrib-utes heat throughout the body, energy transfers fromthe particles of one object to the particles of anotherobject because of their different temperatures. Whenthe energy transfer or heat flows, it moves from thehotter object to the cooler object.

Integrating Physics and Chemistry

Answer

Student answers will vary, butshould indicate that in generalexercise increases circulation.

Real Life

Capillaries No cell in your body is more than a few cell diameters away from a

capillary. At any moment, about 5 percent of your blood is in capil-

laries. In capillaries, gases, nutrients, hormones and other mol-

ecules are transferred from the blood to the body’s cells. Carbon

dioxide and other wastes are transferred from the body’s cells to the

capillaries.

The extensive back-and-forth traffic in the capillaries is possible

because of two key properties. Capillary walls are only one cell

thick, so gas and nutrient molecules easily pass through their thin

walls. Capillaries are also very narrow, with an internal diameter of

about 8 µm (0.0003 in.)—a diameter only slightly larger than the

diameter of a red blood cell. Thus, blood cells passing through a cap-

illary slide along the capillary’s inner wall, as shown in the photo in

Figure 2. This tight fit makes it easy for oxygen and carbon dioxide

to diffuse to and from red blood cells through the capillaries.

VeinsThe walls of veins consist of a much thinner layer of smooth muscle,

than the walls of arteries. They are farther from the heart pump and

exposed to lower pressures. Veins do not receive the pulsing pres-

sure that arteries do.

As shown in Figure 2, veins also differ from arteries in that

they are larger in diameter. A large blood vessel offers less resis-

tance to blood flow than a narrower one, so the blood can move

more quickly through large veins. The largest veins in the human

body are about 3 cm in diameter—about the same diameter as

your thumb.

Most veins have one-way valves. A is a flap of tissue that

ensures that the blood or fluid that passes through does not flow

back. Valves in veins, such as the one shown in Figure 3, prevent the

blood from flowing backward during its trip to the heart. When the

skeletal muscles in your arms and legs contract, they squeeze

against the veins, causing the valves to open and thus, allowing the

blood to flow through. When the skeletal muscles relax,

the valves close, preventing the backflow of blood.

Sometimes the valves in the veins become weak and the

veins become dilated (larger in diameter). Veins that are

dilated because of weakened valves are called varicose

veins. Dilated veins that occur in the anal area are called

hemorrhoids.

Lymphatic SystemBecause the blood plasma is rich in proteins, most of the

fluid remains in the capillaries due to osmotic pressure.

However, every time the heart pumps, some fluids are

forced out of the thin walls of the capillaries. The fluid

that does not return to the capillaries collects in spaces

around the body’s cells. The fluid that collects around the

valve

Magnification: 1223

Figure 3 Valves in veins.

Valves are most abundant

in the veins of the arms

and legs, where the upward

flow of blood is opposed

by gravity.

Real Life

How long are all of your

capillaries?

If all of the capillaries of

your body were laid end to

end, they would extend all

the way across the United

States! The network of

capillaries in the body

is several thousand

miles long.

Finding Information

Find out how capillaries

respond to long-term

aerobic training.

874


Teaching TipStability and Homeostasis Pointout to students that swollen lymphnodes contain large numbers ofimmune system cells (white bloodcells) that are actively engulfingbacteria or virus particles. For thisreason, the nodes become inflamedand tender when the body is fight-ing an infection.

Using the FigureDirect students’ attention toFigure 4. Have them examine thevessels and lymph nodes, includingthe tonsils and spleen. Ask them toidentify some ways in which thelymphatic system is different fromthe cardiovascular system. (Thelymphatic system does not run in acircuit, as the cardiovascular systemdoes. The lymphatic system alsodoes not have its own pump, like theheart of the cardiovascular system.)

GENERAL


Mapping theValves in Veins

Skills AcquiredInferring relationships,identifying functions

Teacher’s NotesInstruct students to allow theirarms and hands to hang in a relaxed manner for 1 to 2minutes before beginning theexperiment. This demonstrationwill also work on the veins inthe back of the hand.

The effect will be more pro-nounced if the blood issqueezed out of the veinbetween the first and secondfinger. Have students do this bygently stroking the vein towardthe heart.

Answers to Analysis1. toward the elbow, and so

toward the heart

2. Blood will have to go againstgravity, enlarging the veinslightly.

3. Blood will pool in the veins inthe legs.

travel through the bloodstream or lymphaticsystem to other parts of the body. Cancer cellsmay spread to lymph nodes near the primarytumor. Cancer cells can also spread to otherparts of the body, distant from the primarytumor. Doctors use the term metastatic diseaseor distant disease to describe cancer that spreadsto other organs or to lymph nodes other thanthose near the primary tumor. When cancer cellsspread and form a new tumor, the new tumor iscalled a secondary, or metastatic, tumor.

Cancer is a group of related diseases thatoccur when cells keep dividing but new cellsare not needed. These extra cells may form amass of tissue, called a tumor. Tumors can beeither benign (not cancerous) or malignant(cancerous). Cancer can begin in any organ ortissue of the body. The original tumor is calledthe primary tumor and is usually named forthe part of the body where it begins.

Metastasis means the spread of cancer. Cancercells can break away from a primary tumor and

REAL WORLDREAL WORLDCONNECTIONCONNECTION

cells is picked up by the lymphatic system and

returned to the blood supply.

The collects and recycles fluids

leaked from the cardiovascular system and is involved

in fighting infections. As shown in Figure 4, the

lymphatic system is made up of a network of vessels

called lymphatic vessels and tiny bean-shaped struc-

tures called lymph nodes. Lymph tissue is also located

in various places throughout the body, including the

thymus, tonsils, spleen, and bone marrow.

Lymphatic vessels carry the leaked fluid, called

lymph, back to two major veins in the neck. Similar to

veins, lymphatic vessels contain valves that prevent the

backflow of the fluid. The fluid is pushed through

the lymphatic vessels when the skeletal muscles in the

arms and legs contract.

The lymphatic system also acts as a key element in

the immune system. Immune cells in the lymph nodes

and lymphatic organs help defend the body against

bacteria, viruses, other infecting microbes, and can-

cerous cells. Lymph nodes, which are concentrated in

the armpits, neck, and groin, sometimes get tender

and swell when they are actively fighting infection

and filled with white blood cells. Health-care pro-

fessionals are trained to detect certain types of

infections by feeling for the lymph node swellings on

the body.

lymphatic system

Mapping the Valves in VeinsBy applying pressure to your arm, you can locate

the valves in the veins of your arm.

Materials

nontoxic felt-tip pen

Procedure

1. Have a classmate make a fist

and extend his or her arm,

with the hand palm up and

slightly below elbow level.

Locate a prominent vein on

the inside of the forearm.

Using one finger, press down

on the vein at a point near the

wrist to block the blood flow.

2. Gently place a second finger

along the vein about 5 cm

from the first finger (toward the

elbow). Release the second

finger, but not the first. The

vein should refill partway. Mark

this point, which indicates the

location of a valve, with a pen.

You may have to try more than

one vein to locate a valve.

Analysis

1. Identify the direction blood

flows in the vein you chose.

2. Propose why the subject

must make a fist and hold his

or her arm slightly down.

3. Infer what effect standing in

one place for long periods of

time might have on the veins

in the legs.

Lymphatic System

Thymus

Lymph node

Spleen

Lymphatic vessel

Bone marrow

Tonsils

Figure 4 Lymphatic tissues. Lymphatic

tissues are located throughout the body.

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Math Skills A human adult hasabout 5 L (1.25 gal) of blood.Plasma is more than 90 percentwater. The body contains some 30trillion red blood cells and about60 billion white blood cells. Everysecond about 2 million new redblood cells are made in the bonemarrow to replace those that die atthe end of their 120-day life span.Have students calculate how manynew red blood cells are made everyhour. ([2,000,000 cells/s] 3 [60s/min] 3 [60 min/h] 57,200,000,000 cells/h) Logical

DemonstrationAdd red water to a test tube tomake it about 40 percent full. Thencarefully add vegetable oil until thetest tube is full. Explain to studentsthat the fluids in the test tuberesemble a centrifuged blood sam-ple. Centrifuging pulls the heaviercomponents to the bottom of thetube. Lighter components stay atthe top. The vegetable oil repre-sents plasma, a yellow fluid. Thered water represents red bloodcells. Note that platelets and whiteblood cells, normally foundbetween the two layers, are notrepresented in this model. VisualLS

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MISCONCEPTION

ALERT

The Color of Blood Students might thinkthat blood is one of two colors, red or blue.Diagrams that portray bright red arteriesand deep blue veins may enhance students’confusion. Oxygenated blood is, in fact,scarlet in color, while deoxygenated bloodis maroon, closer to dark red than to blue.The blue color seen in the superficial veinsof a person with fair skin is misleading: theskin and connective tissue that overlie theveins distort the true color of the bloodwithin the veins.

Answer

Student answers will vary, butshould be well researched.Students should present theirresearch results to the class.

Real Life

StrategiesStrategiesINCLUSIONINCLUSION

Have students create a poster or bulletinboard of the Lymphatic System. UsingFigure 4, have students label the differentlymphatic tissues found in the body. Theymay add note cards describing the functionof each of the tissues and attach them to theposter or bulletin board. They may be ableto present their findings to the class and beable to tell how doctors use lymph nodes todetect infection.

• Learning Disability • Attention DeficitDisorder

Real Life

Several proteins from

vampire bats stop blood

from clotting.

These proteins, including

one named draculin, are

being used to develop

drugs to fight heart

disease.

Finding Information

Investigate other drugs

that are currently being

developed to help fight

heart disease.

Components of BloodBlood has been called the river of life because it is responsible for

transporting so many substances throughout the body. In life-

threatening situations, a person’s blood volume is carefully moni-

tored, as shown in Figure 5. Typically, blood appears to us as a red,

watery fluid. Blood is composed of water, but it also contains a vari-

ety of molecules dissolved or suspended in the water, as well as

three kinds of cells.

Plasma About 60 percent of the total volume of blood is , the liquid

portion of blood. Plasma is made of 90 percent water and 10 percent

solutes. The solutes include metabolites, wastes, salts, and proteins.

Water Water in the plasma acts as a solvent. It carries other

substances.

Metabolites and Wastes Dissolved within the plasma are glucose

and other nutrient molecules. Vitamins, hormones, gases, and

nitrogen-containing wastes are also found in plasma.

Salts (Ions) Salts are dissolved in the plasma as ions. The chief

plasma ions are sodium, chloride, and bicarbonate. The ions have

many functions, including maintaining osmotic balance and regu-

lating the pH of the blood and the permeability of cell membranes.

Proteins Plasma proteins, the most abundant solutes in plasma,

play a role in maintaining the osmotic balance between the cyto-

plasm of cells and that of plasma. Water does not move by osmosis

from the plasma to cells because the plasma is rich in dissolved pro-

teins. Some of the plasma proteins are essential for the formation

of blood clots. Other proteins called antibodies help the body fight

disease.

Some plasma proteins help thicken the blood. The thickness of

blood determines how easily it flows through blood vessels. Other

plasma proteins serve as antibodies, defending the body

from disease. Still other plasma proteins, called clotting pro-

teins or blood-clotting factors, play a major role in blood

clotting. When blood is collected for clinical purposes, the

blood-clotting factors are removed from the blood and stored

for later use.

Blood Cells and Cell Fragments About 40 percent of the total volume of blood is cells and cell

fragments that are suspended in the plasma. There are three

principal types of cells in human blood: red blood cells, white

blood cells, and platelets.

Red blood cells Most of the cells that make up blood are

—cells that carry oxygen. Each milliliter of

human blood contains about 5 million red blood cells. Red

blood cells are also called erythrocytes (eh RIHTH roh seyets).

red blood cells

plasma

Figure 5 The river of life.

The loss of too much blood

can create a life-threatening

situation.

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Using the FigureRefer students to Figure 6. Havestudents relate the shapes and sizesof the cells and cell fragments inthe figure to their functions. (Redblood cells have a large surface areafor gas diffusion, and the characteris-tic “donut” shape enables them tosqueeze through tiny capillaries. Theshape of the white blood cells enablesthem to engulf other particles, andtheir size ensures that they can defendthe body against a large number ofinvaders. The shape of the plateletsallows them to stick together to forma small plug.) Have students com-pare the pictures with preparedmicroscope slides of human blood.

Visual

ActivityBlood Composition Blood hasseveral different components, andlearning them can be confusing.Have students construct aGraphic Organizer, such as theone shown at the bottom of thispage, that describes the structureand function of each of the bloodcomponents discussed in the text.Students should also show thecomposition of plasma, the fluidportion of the blood. Visual

Group ActivityBlood Diseases Have studentswork in small groups to conductlibrary or Internet research on dis-eases and disorders of the bloodand blood vessels. (Some examplesof diseases they could investigateinclude cancers such as leukemiaand lymphoma, anemia, sickle-celldisease, hemophilia, Raynaud’sPhenomenon, Thalassemia, andvon Willebrand Disease.) Studentsshould collect information on thecauses, symptoms, treatment, andother pertinent information. Haveeach group prepare a report topresent to the entire class.

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Graphic Organizer

Blood

Metabolites

Wastes

Salts

Proteins

Platelets—blood clotting

Plasma—liquid portion of blood

Red blood cells—carry oxygen

White blood cells—defend

body against disease

Use this graphic organizerwith Activity on this page.

Most of the interior of a red blood cell is packed with hemo-

globin. Hemoglobin is an iron-containing protein that binds oxygen

in the lungs and transports it to the tissues of the body. Mature red

blood cells do not have nuclei and therefore cannot make proteins

or repair themselves. Red blood cells have a biconcave shape, as

shown in Figure 6, and a short life span (about 4 months). New red

blood cells are produced constantly by stem cells, specialized cells

in bone marrow.

An abnormality in the number or function of red blood cells can

result in anemia. (uh NEE mee uh) is a condition in which

the oxygen-carrying ability of the blood is reduced. Anemia may

result from blood loss or nutritional deficiencies.

White Blood Cells There are only 1 or 2 white blood cells, or

leukocytes (LOO koh sites), for every 1,000 red blood cells.

are cells whose primary job is to defend the body

against disease. White blood cells, shown in Figure 6, are larger

than red blood cells and contain nuclei.

There are many different kinds of white blood cells, each with a

different immune function. For example, some white blood cells

take in and then destroy bacteria and viruses. Other white blood

cells produce antibodies, proteins that mark foreign substances for

destruction by other cells of the immune system.

Platelets In certain large cells in bone marrow, bits of cytoplasm

are regularly pinched off. These cell fragments, called

(PLAYT lihts), are shown in Figure 6. Platelets play an important

role in the clotting of blood. If a hole develops in a blood vessel

wall, rapid action must be taken by the body, or blood will leak out

of the system and death could occur.

When circulating platelets arrive at the site of a broken vessel,

they assume an irregular shape, get larger, and release a substance

that makes them very sticky. The platelets then attach to the protein

fibers on the wall of the broken blood vessel and eventually form a

sticky clump that plugs the hole.

platelets

White blood cells

Anemia

Red blood cells White blood cell Platelets

Figure 6 Three kinds of

blood cells. Red blood cells

transport oxygen and some

carbon dioxide. White blood

cells help defend the body

against disease. Platelets are

involved in blood clotting.

www.scilinks.org

Topic: White Blood Cells

Keyword: HX4190

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Teaching TipBlood Clotting Tell students thatwhen people cut themselves shaving,they often put a piece of tissue overthe cut. The fibers in the tissue actlike platelets, beginning the clottingprocess by providing a frameworkfor red blood cells to be caught.



Blood Witness

Teaching StrategiesExplain to students that in bloodsplatter analysis, forensic scien-tists study the patterns made bydrops of blood at the crimescene. This evidence can helpinvestigators recreate the eventsof the crime. The patterns madeby blood droplets when they fellor were sprayed against thewalls, floor, or ceiling, can revealthe positions of the victim andthe assailant, and their directionof movement. They can alsoindicate the impact and velocityof a murder weapon, such as afist (large, slow drops), or a gunshot (many, tiny droplets).

DiscussionWhy do forensic investigatorsneed white blood cells in orderto perform DNA analysis? (Whiteblood cells have nuclei, which con-tain DNA. At maturity, red bloodcells do not have nuclei. Bloodplasma does not contain cells.)

Forensics Labs AppendixTurn to pp. 1048–1071 forforensics lab activities and morestudent information on foren-sics techniques. TECHNOLOGYTECHNOLOGY

CONNECTIONCONNECTION

blood clotting proteins are imbedded in a film, which is freeze-dried onto the bandage.The bandage is pressure-applied, which helpsactivate its clotting agents, which set in about a minute. The bandage is lightweight and can be stored at room temperature, but it must bepacked in a watertight seal or it will “clot” inthe bag by absorbing water from the air. Drybandages retard chemical breakdown andnegate the need for refrigeration, importantcharacteristics for a field dressing.

Since uncontrolled bleeding is the most commoncause of death for soldiers wounded on the bat-tlefield, military medical researchers have longsought improved bandages that can be used inthe front lines. Army medical researchers havehelped to develop an improved field bandagethat can reduce bleeding by as much as 85 percent compared to previous dressings. Nowundergoing testing, the new bandage containsblood-clotting proteins. It is about four inchessquare and a quarter of an inch thick. The

Transparencies

TR J29 Blood Clotting Cascade

TR J25 Systemic Circulation

For wounds such as an open cut, the platelets

release a clotting enzyme that activates a series of

chemical reactions. Eventually, a protein called fib-

rin is formed. The fibrin threads form a net, trapping

blood cells and platelets, as shown in Figure 7. The

net of fibrin and platelets develops into a mass, or

clot, that plugs the blood vessel hole. A mutation in

a gene for one of the blood-clotting proteins causes

hemophilia, a blood clotting disorder.

Blood Type Occasionally, an injury or disorder is so serious

that a person must receive blood or blood compo-

nents from another person. The blood types of the

recipient, the person receiving the blood, and that

of the donor, the person giving the blood, must

match. Blood type is genetically determined by the

presence or absence of a specific complex carbo-

hydrate found on the surface of red blood cells.

One system used to type blood is the

. Under this system, the

primary blood types are A, B, AB, and O. The let-

ters A and B refer to complex carbohydrates on

the surface of red blood cells that act as antigens,

substances that can provoke an immune response.

ABO blood group system

Platelets release

clotting protein

(enzyme)

Fibrin net forms,

trapping blood cells

and platelets

Clotting

reaction occurs

Blood vessel

damage

Stimulus

Blood clot

Result

Fibrin net Blood cells

Blood is the most common

evidence in the world of

criminal justice. Serology is the

scientific study of blood and its

components. A forensic serolo-

gist analyzes blood, semen,

saliva, and other body fluids to

help solve crimes.

A Link Between Suspect

and Victim

Many criminals attempt to clean

up a violent crime scene, but

blood often remains behind.

Investigators may find blood

under a victim’s fingernails, on

automobile upholstery, on carpet

or clothing, or sometimes even in

a household drain. A forensic

serologist first determines if the

substance found is blood, then

verifies that it is human blood.

In a violent crime, blood can

reveal the identities of both the

victim and the criminal. Red

blood cells contain telltale anti-

gens attached to their surfaces.

Blood plasma contains proteins

that serve as antibodies. Using

antibodies, serologists can

determine the blood type of a

sample.

Positive Identification

For decades, ABO blood typing

was the primary tool of forensic

serologists. One problem, how-

ever, is that blood evidence from

two or more individuals can

combine. For example, a type

AB sample

might actu-

ally consist

of blood

from a type

A victim and a type B assailant.

ABO blood typing evidence

could exclude a suspect whose

blood type did not match the evi-

dence. But it could not positively

identify a suspect.

Today blood is commonly

used in DNA testing, which

results in highly accurate identifi-

cation. DNA evidence can also

indicate familial relationships,

which can help investigators dis-

cover that the assailant is related

to the victim.

Blood Witness

Figure 7 Blood-clotting cascade

The release of enzymes

from platelets at the site

of a damaged blood

vessel initiates a

“clotting cascade.”

878


Answers to Section Review

1. the cardiovascular system

2. arteries—thick, elastic walls and thick smoothmuscle layers that carry blood under high pres-sure away from the heart; veins—thin wallsand thin smooth muscle layers that carry bloodunder low pressure to heart; capillaries—thinwalls that allow exchange of substances in theblood with the tissues

3. The lymphatic system collects and recycles flu-ids leaked from the circulatory system and isinvolved in fighting infections.

4. Water is the solvent for dissolved substances inthe blood. Red blood cells carry oxygen to bodytissues. White blood cells defend the bodyagainst pathogens. Platelets help keep the venoussystem intact by patching tears in blood vessels.

5. A and O are both safe.

6. A. Incorrect. There are no O antigens.B. Incorrect. Both antigens are not present.C. Incorrect. Neither antigen is present.D. Correct. Type O has neither A nor Bantigens.

ReteachingHave students observe preparedslides of normal blood and bloodwith abnormalities such asleukemia (cancer of the whiteblood cells) or an iron deficiency.Have them compare and contrastwhat they see. (With leukemia, thenumber of white cells may be greater.An iron deficiency may cause the redcells to be lighter in color and fewerin number.)

Quiz1. Which type of blood vessel is

involved in the exchange ofmaterials between the blood andbody tissues? (capillaries)

2.What happens to excess fluidthat collects in body tissues? (It is picked up in lymph vesselsand returned to the cardiovascularsystem.)

3. Which type of blood cell is thesmallest whole cell?(red blood cell)

AlternativeAssessmentHave students explain the adaptivevalue of the location of arteries(generally found far below thebody’s surface), veins (locatedcloser to the surface), and capillar-ies (distributed all over the body).(Arteries carry blood under high pressure, so a tear or rupture is morelife threatening than it is in a vein.Therefore it is beneficial to protectarteries deep within the body.Capillaries must come into contactwith every cell in the body to performtheir exchange function.)

GENERAL

GENERAL

CloseClose


As summarized in Table 1, people with type A blood have the

A antigen on their red blood cells. People with type B blood have the

B antigen. People with type AB blood have both the A and the B

antigen, while those with type O blood have neither antigen.

Antibodies are defensive proteins made by the immune system. Peo-

ple with type A blood produce antibodies against the B antigen, even

if they have never been exposed to it. In these people, type B red blood

cells clump and can block blood flow. For this reason, blood transfu-

sion recipients must receive blood that is compatible with their own.

People with type AB blood are universal recipients (they can

receive A, B, AB, or O blood) because they do not have anti-A or

anti-B antibodies. Type O individuals are universal donors (they can

donate blood to those with A, B, AB or O blood) because their blood

cells do not carry A or B antigens and therefore do not react with

either anti-A or anti-B antibodies.

Rh Factor Another important antigen on the surface of red blood cells is

called , which was originally identified in rhesus mon-

keys. People who have this protein are said to be Rh1, and those

who lack it are Rh2. When an Rh2 mother gives birth to an Rh1

infant, the Rh2 mother begins to make anti-Rh antibodies. The

mother’s antibodies may be passed to an Rh1 fetus in a future preg-

nancy, which can lead to fetal death.

Rh factor

Table 1 Blood Types

Blood Antigen on the Antibodies Can receive Can donate type red blood cell in plasma blood from blood to

A A B O, A A, AB

B B A O, B B, AB

AB A, B Neither A nor B O, A, B, AB AB

O Neither A nor B A, B O O, A, B, AB

Section 1 Review

Name the system that transports nutrients, oxygen,wastes, hormones, and heat.

Compare the structures and functions ofarteries, capillaries, and veins.

Describe the role of the lymphatic system.

Summarize the functions of water, red bloodcells, white blood cells, and platelets.

Predict the blood types that would be safe for a person with type A blood to receive during atransfusion.

Real Life

RhoGAM is a blood

product that can sup-

press the ability to

respond to Rh1 red

blood cells.

It is given to an Rh2

woman who is pregnant

with an Rh1 fetus to pre-

vent her from developing

antibodies that would

harm her baby.

Which antigens are on thered blood cells of a person with type O blood?

A 0 antigens C Either A or B antigens

B Both A and B D Neither A nor B antigens antigens

Standardized Test PrepStandardized Test Prep

879


Overview

Before beginning this sectionreview with your students theobjectives listed in the StudentEdition. Students will map how thestructures of the cardiovascular sys-tem pump blood around the body.They will also describe electricalactivity in the heart. Finally, theywill list some disorders of the heart.

Ask students to write a few sen-tences that describe how the muscletissue of the heart is different fromother types of muscle tissue.(Answers may vary.)

Demonstration

Show students that when blood isfar from the heart, it travels withless pressure. You will need plasticsyringes and two pieces of hosingthat fit snugly on their ends. Onehose should be about 8 cm (3 in.)long and the other about 15 cm(6 in.). Fill each syringe and forcethe water out. The stream shouldtravel about 8 to 15 cm (3 to 6 in.)from the end of the longer hose(vein), and 15 to 30 cm (6 to12 in.) from the end of the shorterhose (capillary). Be sure to applyequal pressure to the plunger eachtime so students appreciate the factthat it is distance from plunger tipto exit, not pressure on the plunger,that causes the change. VisualLS

MotivateMotivate

Bellringer

FocusFocus

Section 2

880 Chapter 38 • Circulatory and Respiratory System


• Problem Solving GENERAL




• Problem Solving WorksheetComputing Rates and HeartEfficiency GENERAL

Planner CD-ROM

Transparencies

TR Bellringer

TR J24 Circulatory Loops in the Human Body

TR J26 Path of Bloodflow Through the Heart

TR J19 Electrical Regulation of the Heart

Section 2 The Heart

A Muscular PumpBlood vessels allow for the movement of blood to all cells in the

body. The pumping action of the heart, however, is needed to pro-

vide enough pressure to move blood throughout the body. The heart

is made up mostly of cardiac muscle tissue, which contracts to

pump blood.

Two Separate Circulatory Loops As shown in Figure 8, the human heart has two separate circulatory

loops. The right side of the heart is responsible for driving the pul-

monary (PUHL muh nehr ee) circulation loop, which pumps

oxygen-poor blood through the pulmonary arteries to the lungs.

Gas exchange—the release of carbon dioxide and pick up of oxy-

gen—occurs in the lungs. The oxygenated blood is then returned to

the left side of the heart through pulmonary veins.

The left side of the heart is responsible for driving the systemic

circulation loop, which pumps oxygen-rich blood through a net-

work of arteries to the tissues of the body. Oxygen-poor blood is

then returned to the right side of the heart through the veins.

Objectives

● Differentiate the pulmonary

circulation loop from

the systemic circulation

loop.

● Summarize the path that

blood follows through the

heart.

● Name the cluster of heart

cells that initiates contraction

of the heart.

● Describe three ways to

monitor the health of the

circulatory system.

● Name two vascular diseases,

and identify factors that

contribute to their

development.

Key Terms

atrium

ventricle

vena cava

aorta

coronary artery

sinoatrial node

blood pressure

pulse

heart attack

stroke

Veins

Valves

Body Capillaries

Arteries

Pulmonary

vein

Pulmonary

circulation

Pulmonary

artery

Lung

capillaries

Systemic

circulation

Oxygen-poor blood Oxygen-rich blood

Heart

The pulmonary circuit transports blood between the heart and lungs; the

systemic circuit transports blood between the heart and the rest of the body.

Figure 8 Simplified diagram mapping

880


Teaching TipNourishing the Heart Point outto students that the heart cannotget nutrients and oxygen from theblood in its own chambers. This isbecause the heart muscle is toothick for diffusion to be an effectivemeans of distribution. Instead, theheart must rely on the coronaryarteries to sustain it. These twoarteries lie in grooves that spiralaround the heart. An obstruction inone of their branches often necessi-tates bypass surgery to restoreproper blood flow to the heart.Restricted blood flow can result inangina pectoris, which is chestpain, or a myocardial infarction,which is a heart attack. Heart cellsdie during an infarction, which lim-its the heart’s pumping efficiency.

Using the FigureHave students examine Figure 9.Have them use their fingers to tracethe path that blood follows throughthe heart. Tell students that althoughthe heartbeat is described for con-venience as occurring first on theright side and then on the left, themovement of blood occurs on bothsides simultaneously. Have studentscompare the sizes of the left andright ventricle walls. Ask why theleft ventricle wall is thicker than theright. (Blood is pumped to the entirebody from the left ventricle. Bloodfrom the right ventricle goes only asfar as the lungs.) Visual

DemonstrationShow students a transparency containing a diagram of a fish’s car-diovascular system. Point out thatthe fish’s cardiovascular system hasonly one circuit in it, rather than thetwo circuits found in mammals.Trace the pathway of blood fromthe heart, over the gills, to body tissues, and back to the heart. Askstudents why the number of cardio-vascular system circuits of fish andmammals might be different. (Fishare ectothermic animals that havelower metabolic demands than mam-mals; therefore, their needs for oxygenare also lower.)

GENERAL

LS

TeachTeach


heart rate and/or by increasing the strength of the heart beat. The reduction in vascularresistance results in higher levels of oxygenbeing delivered to body tissues. A conditionedathlete’s exercising heart rate is slower thanthat of an unconditioned person. The athlete’scardiac output also increases less. Goingfrom the resting to maximal exercise states,oxygen consumption increases by 10 times inuntrained people and by 20 to 30 times inconditioned athletes.

Aerobic exercise conditions the heart andlungs by increasing the oxygen available to thebody and by enabling the heart to use oxygenmore efficiently. During dynamic aerobic exer-cise, such as walking, tennis, soccer, andvolleyball, the cardiovascular system respondsby increasing oxygen supply to the muscles.This occurs as a result of the nervous systemincreasing cardiac output and reducing vascu-lar resistance in small blood vessels. Cardiacoutput (the amount of blood pumped witheach heart rate) is increased by increasing the

REAL WORLDREAL WORLDCONNECTIONCONNECTION

Circulation of BloodAs shown in Figure 9, the heart has a wall that divides the right and

left sides of the heart. At the top of the heart are the left and right

atria (AY tree uh). The (singular, atrium), are chambers that

receive blood returning to the heart. Below the atria are the left and

right , thick-walled chambers that pump blood away

from the heart. A series of one-way valves in the heart prevent blood

from moving backward. Figure 9 summarizes the path blood

follows through the heart:

Two large veins called the inferior and superior vena

cava collect all of the oxygen-poor blood from the body. The

venae cavae empty blood directly into the right atrium of the

heart.

The blood from the right atrium moves into the right ventricle.

As the right ventricle contracts, it sends the blood into the pul-

monary arteries.

The pulmonary arteries carry the blood to the right and left

lungs. At the capillaries of the lungs, oxygen is picked up and

carbon dioxide is unloaded.

The freshly oxygenated blood returns from the lungs to the left

side of the heart through the pulmonary veins, which empty the

blood directly into the left atrium.

From the left atrium, the blood is pumped into the left ventricle.

vena cava

ventricles

atriaInterpreting Graphics

In human anatomy, the

terms left and right always

refer to the left and right

from the perspective of the

subject. This will help you

understand why the terms

left and right appear

reversed in anatomical

drawings, such as that

of the heart in Figures 8

and 9.

Superior vena cava

sends O2-poor blood

from upper body toright atrium.

Blood from aorta to body

Aorta sends blood to the coronaryarteries, the brain, and the rest ofthe body.

Pulmonary veins

return blood to the left atrium from the lungs.

Left atrium

sends blood to theleft ventricle.

Left ventricle

sends blood to the aorta.

Right atrium

sends blood to theright ventricle.

Right ventricle

sends blood to thepulmonary artery.

Left lungRight lung

Inferior vena cava

sends O2-poor blood

from lower body toright atrium.

Pulmonary arteries

send blood to the lungs.

The arrows trace the path of blood as it travels through the heart.

Figure 9 Blood flow through the heart

881


Teaching TipThe Intrinsic Heartbeat Pointout to students that cardiac musclecells have an intrinsic, or self-initiated, beat. Contractions of theheart muscle are not produced bystimulation from nerves. Nervescontrol only the rate of the heart’scontractions. In addition, cardiacmuscle cells influence each other.The sinoatrial node and the atrio-ventricular node (which stimulatesthe ventricles to contract) triggercontractions of the other heartmuscle cells in the same chamber.Thus, contraction of the cells of theatria and then of the ventricles issynchronized.

Demonstration Invite the school nurse to demon-strate how a stethoscope can beused to hear the sounds of a heart-beat. Tell students that the “lubb”and “dup” sounds that are heardare made when the valves of theheart close. Explain that the valvesof the heart open with each con-traction and let blood through tothe next chamber or to an artery.The valves then close to stop bloodfrom moving backward. In thisway, the valves keep blood movingthrough the heart and out to thebody. Valve disease occurs when avalve doesn’t work the way itshould. If a valve doesn’t open allthe way, less blood can movethrough the smaller opening. If avalve doesn’t close tightly, bloodmay leak backward. A heart mur-mur is an abnormal sound that canbe heard when listening to a per-son’s heartbeat.



TECHNOLOGYTECHNOLOGYCONNECTIONCONNECTION

that helps the heart beat in a regular rhythm.Some pacemakers are permanently implantedin the chest wall, and some are worn exter-nally. The pacemaker sends electrical impulsesto the heart, which helps to regulate theheart’s rhythm. An electrode is placed next tothe heart wall and small electrical chargestravel through the wire to the heart.

When the heart’s rhythm is disrupted causingthe heartbeat to be too fast, too slow, or irregular, an artificial pacemaker may becomenecessary. These disruptions may be caused bya blockage in the electrical pathway that regu-lates heart rhythm, or by some other defect inthe heart’s natural pacemaker. An artificialpacemaker is a small, battery-operated device

Sinoatrial

(SA) node

After a slight delay that permits the left atrium to empty com-

pletely, the left ventricle contracts. The walls of the left ventricle

are muscular, so the left ventricle’s contraction is forceful.

The blood then enters one of the largest arteries of the body, the

(ay OHR tuh).

The first arteries to branch from the aorta are the

(KOHR uh neh ree) , which carry freshly oxygenated blood

to the heart muscle. Other arteries also branch from the aorta and

carry oxygen-rich blood to all parts of the body.

After delivering oxygen to the cells of the body and picking up

carbon dioxide, the cycle continues when blood returns to the heart

through the inferior or superior venae cavae.

Initiating ContractionContraction of the heart is initiated by a small cluster of cardiac mus-

cle cells called the (SIE noh ay tree uhl) , which is

embedded in the upper wall of the right atrium. The cells that make

up the sinoatrial node (SA node, for short) act as the pacemaker of

the heart. These cells “fire” an electrical stimulus in a regular

rhythm. Each stimulus is followed immediately by a contraction that

travels quickly in a wave and causes both atria to contract almost

simultaneously, as shown in Figure 10.

The wave of contraction spreads from the atria to the ventricles,

but almost one-tenth of a second passes before the ventricles start

to contract. The delay permits the atria to finish emptying blood

into the ventricles before the ventricles contract simultaneously.

The wave of contraction is conducted rapidly over both ventricles

by a network of fibers in the heart.

On average, heart contractions occur at a rate of about 72 times

per minute. During sleep the rate decreases, and during exercise it

increases. The SA node is controlled by two sets of nerves with

antagonistic (opposite) signals and is influenced by many factors,

including hormones, temperature, and exercise.

Monitoring the Cardiovascular SystemHeart disease is one of the leading causes of death among people in

the United States. Health professionals use several different meth-

ods to monitor the health of the circulatory system.

Blood pressure Doctors routinely measure patients’ blood pressure.

is the force exerted by blood as it moves through

blood vessels. Blood pressure readings provide information about

the conditions of the arteries.

Blood pressure is measured with a blood pressure cuff and gauge,

shown in Figure 11. Blood pressure is expressed in terms of mil-

limeters of mercury (mm Hg) and is usually reported as the systolic

pressure written over the diastolic pressure. The first number, the

systolic pressure, is the pressure exerted when the heart contracts

and blood flows through the arteries. The diastolic pressure is the

pressure exerted when the heart relaxes.

Blood pressure

nodesinoatrial

arteries

coronary

aorta

Figure 10 Electrical

regulation of the heart. The

SA node, or pacemaker, fires

ahead of each heart contrac-

tion. The wave of contraction

spreads across both atria and

delays for an instant before it

travels to the ventricles.

Figure 11 Monitoring

blood pressure. Blood

pressure is measured with

a blood pressure cuff, a

stethoscope, and a mercury

(Hg) column gauge.

882


Teaching TipHeart Attacks Tell students thathypertension, or high blood pres-sure, is a serious health conditionbecause it is the major cause ofheart failure, kidney failure, andstroke. Ask students to use outsidesources to research hypertensionand prepare a report that explainsthe causes of this condition, how itcan be prevented or treated, andthe incidence of hypertension in theUnited States compared with thatof other countries.

Group ActivityMeasuring Blood Pressure Havethe school nurse demonstrate howa sphygmomanometer works.Remind students that blood pres-sure readings include two numberthe systolic and diastolic pressures,represented as a ratio. The systolicreading, the first value, is the pres-sure on the artery walls exerted bythe contracting ventricles. The dias-tolic reading, the second value, isthe pressure on the blood vesselwalls during ventricular relaxation.

GENERAL


What Is a Heart Attack?

Teaching StrategiesBring in a sheep heart or apicture of a human heart andpoint out the coronary arteriesto students.

Discussion• Identify the ways arteriesbecome blocked. (blood clots,atherosclerosis, arteriosclerosis)

• Why do doctors recommendthat certain people take anaspirin a day? (Aspirin acts asan anticoagulant, keeping theblood flowing.)

• How can aspirin help preventheart attacks? (Thinner bloodis less likely to clot, but it willnot prevent plaques from com-ing loose or other causes forheart attacks.)

Obesity Health problems resulting fromoverweight and obesity could reverse manyof the health gains achieved in the U.S. inrecent decades, according to a SurgeonGeneral’s “call to action” issued in 2001.“Overweight and obesity may soon cause asmuch preventable disease and death as ciga-rette smoking,” then Surgeon GeneralDavid Satcher said. Being overweight is arisk factor for heart disease, high bloodpressure, diabetes, and other conditions.

Approximately 300,000 U.S. deaths a year areassociated with obesity and overweight (com-pared to more than 400,000 deaths a year asso-ciated with smoking). The total direct andindirect costs attributed to overweight and obe-sity amounted to $117 billion in the year 2000.In 1999, an estimated 61 percent of U.S. adultswere overweight, along with 13 percent of chil-dren and adolescents. Obesity among adultshas doubled since 1980, while the percentage ofoverweight children and adolescents has dou-bled since the early 1970s.

Transparencies

TR J20 Electrocardiogram

TR J19 Electrical Regulation of the Heart

Normal blood pressure is less than 120 for systolic pressure and

less than 80 for diastolic pressure. An example of a normal reading

would be written 115/75 mm Hg. These figures indicate the blood

is pushing against the artery walls with a pressure of 115 mm Hg as

the heart contracts and 75 mm Hg as the heart rests.

Many Americans suffer from a condition called high blood pres-

sure, or hypertension. High blood pressure places a strain on the

walls of the arteries and increases the chance that a vessel will burst.

Left untreated, hypertension can lead to heart damage, brain dam-

age, or kidney failure. Regular aerobic activity can help people to

maintain a healthy blood pressure. Hypertension can be easily diag-

nosed and usually can be controlled by medicine, diet, and exercise.

Electrocardiograms (ECGs or EKGs) A common way to monitor the

heart’s function is to measure the tiny electrical impulses produced

by the heart muscle when it contracts. Because the human body is

composed mostly of water with dissolved ions, it conducts electrical

currents. A small portion of the heart’s electrical activity reaches the

body surface. As shown in Figure 12, an instrument called an electro-

cardiograph uses special sensors to detect the electrical activity. A

recording of these electrical impulses is called an electrocardiogram,

abbreviated as ECG or EKG. In one normal heartbeat, three succes-

sive electrical-impulse waves are recorded, as shown in Figure 12.

Heart Rate It takes only a watch with a second hand to measure

your pulse. Your is a series of pressure waves within an artery

caused by the contractions of the left ventricle. A person’s pulse is

an indicator of his or her heart rate—how fast or slow the heart is

beating. Each time the blood surges from the aorta, the elastic walls

in the blood vessels expand and stretch. This rhythmical expansion

can be felt as a pulse in areas where the vessels near the surface of

the skin. The number of pulses counted per minute represents the

number of heartbeats per minute. The most common site for taking

a pulse is at a radial artery, on the thumb side of each wrist. The

average pulse rate ranges from 70 to 90 beats per minute for adults.

pulse

Electrocardiogram

Atria contract Ventricles relax

Ventricles contract

Atria relax

Figure 12 Monitoring

heart contractions. The

electrical changes with each

heart contraction can be

detected with an electrocar-

diograph. The characteristic

up-and-down waves are

analyzed to assess the health

of the heart.

The Greek word for heart is

kardia. Because of the k in

this word, electrocardiogram

is sometimes abbreviated as

EKG instead of ECG.

883


ReteachingReview the Demonstration on thefirst page of this section. Havestudents infer which blood vesselwould have the highest blood pres-sure. (the aorta, as blood is leavingthe left ventricle) Which bloodvessel would have the lowest bloodpressure? (the vena cava, as blood isreturning to the right atrium) Havethem justify their choices.

Logical

Quiz1. Blood leaving the heart through

the pulmonary artery goes to________ . (the lungs)

2.How is a heartbeat stimulated?(by electrical stimuli from thesinoatrial (SA) node in the rightatrium that stimulates other heartcells to contract)

3. What is an EKG? (electrocardio-gram, a record of the electricalactivity of the heart)

4. What is a heart attack? (death ofan area of the heart that has hadits blood supply cut off)

AlternativeAssessmentHave students design a crosswordpuzzle using key vocabulary wordsfor the heart and circulation.

VerbalLS

GENERAL

GENERAL

LS

CloseClose


1. left atrium, left ventricle, aorta, arteries, capil-laries, veins, vena cava, right atrium, rightventricle, pulmonary arteries, lungs, and pul-monary veins

2. When the sinoatrial node is activated, it causesthe atria to contract. After about a one-tenth ofa second pause, the ventricles contract.

3. The SA node acts as a heart pacemaker by pro-viding an electrical stimulation that regulatesthe heart’s rhythm.

4. EKG, blood pressure, and pulse can be used tomonitor cardiovascular system condition.

5. A heart attack occurs when a blood vessel inthe heart becomes blocked. A stroke occurswhen a blood vessel in the brain becomesblocked.

6. A. Correct. Blood moves from the right ventri-cle to the lungs for oxygenation, then back tothe heart. B. Incorrect. Blood from the leftventricle enters the aorta. C. Incorrect. Bloodmoves from the right atrium to the right ventri-cle. D. Incorrect. Blood leaving the left ventriclemoves to the rest of the body except the lungs.


Diseases of the blood vessels serving the heart and brain are lead-

ing causes of premature death and disability in the United States.

When either the heart or the brain does not get enough blood, parts

of the organ die. A occurs when an area of the heart

muscle stops working and dies. When an area of the brain dies the

result is a . Death or varying degrees of disability may result.

Factors that contribute to heart attacks and strokes are cigarette

smoking, lack of physical activity, diets high in saturated fats, and

unmanaged stress.

stroke

heart attack

What Is a Heart Attack?

You may feel a sharp, crushing, squeezing pain inyour chest. You may have mild pain in your jawsor down an arm. You may break into a cold sweatand feel nauseated. Some of these symptomsoccur in almost 2 million Americans each yearwhen they experience a heart attack. Some people experience almost no symptoms.

Why Do Heart Attacks Occur? Heart attacks usually happen when the arteriesthat deliver oxygen to the heart, the coronaryarteries, become blocked. Heart cells begin to die very quickly without blood. If a large part ofthe heart is affected, the victim can die immedi-ately or within a few days or weeks.

Blockage of ArteriesA blood clot formed somewhere else in the bodycan break loose and flow to the heart or to thebrain, where it blocks the flow of blood. Bloodflow is also blocked by the buildup of fattydeposits, including cholesterol, a condition calledatherosclerosis (ath uhr oh skluh ROH sihs).

When calcium is deposited in the fatty buildup,the condition is called arteriosclerosis (ahr tihr eeoh skluh ROH sihs), or hardening of the arteries.Hardened arteries cannot expand to handle thevolume of blood that enters every time the heartcontracts. Pressure builds up in the artery andcauses the heart to work harder.

PreventionHigh blood pressure, high cholesterol levels, andcigarette smoking are all controllable risk factorsin heart disease. Not smoking at all, early diagno-sis and treatment of high blood pressure, regularmedical checkups, a healthy diet, and regularexercise can all help prevent a heart attack ordecrease the severity of one.

FurtherExploring Further

Normal artery Artery with fatty deposits

Fat

Cholesterol

crystals

Summarize the path of blood through the bodystarting and ending with blood that has justreturned from the lungs to the heart.

List the sequence of events that results in atrialand ventricular contraction.

Describe the function of the SA node.

Identify three ways that the condition of the cardiovascular system can be monitored.

Differentiate between a heart attack and astroke.

When the right ventriclecontracts, it pumps blood to the

A lungs. C right atrium.

B aorta. D rest of the body.


Section 2 Review

884


Section 3

Overview

Before beginning this sectionreview with your students theobjectives listed in the StudentEdition. Students will sequence thestructures through which air passesas it enters and exits the body. Theywill describe the mechanism ofbreathing and how it is regulated.They will also explain how oxygenis transported in the blood, how itis exchanged with carbon dioxidein body tissues, and how carbondioxide is transported in the blood.Finally, students will develop anappreciation for the symptoms ofand treatments for several respira-tory diseases.

Ask students to write a sentence ortwo describing why their breathingrate would increase from exercise orfright. (In either case, the respiratorycenter in the brain would stimulatethe muscles involved in breathing toincrease their rate of contraction andprepare the body to meet either actualor potential oxygen needs.)

Discussion/

Question

Point out that air pressure affectsrespiration in humans. Gases areexchanged between the air in thealveoli and the blood in the capil-laries entirely by diffusion. Havestudents postulate why a personbreathes deeper and faster athigher altitudes, where there isdecreased pressure. (At high altitudes, less oxygen is available. At 6,000 m [19,685 ft], the oxygensaturation of hemoglobin is only 67 percent, compared to 98 percentat sea level. One must become accli-mated over time to the low levels ofoxygen.) Athletes who train at highaltitudes tend to perform better inlower altitudes than those whotrain in low altitudes. LogicalLS

GENERAL

MotivateMotivate

Bellringer

FocusFocus




• Supplemental Reading GuideMicrobe Hunters

• Occupational Application WorksheetRespiratory Therapist GENERAL

Planner CD-ROM

Transparencies

TR Bellringer

TR J31 The Human Respiratory System


• Active Reading

• Data Sheet for Math Lab

• Data Sheet for Quick Lab GENERAL

GENERAL

GENERAL


Gas ExchangeA person can go without water for a few days and without food for

more than a week. But if a person stops breathing for more than a

few minutes, he or she will die. Breathing is the means by which

your body obtains and releases gases. Oxygen is used by your cells

to completely oxidize glucose and then make ATP, the main energy

currency in your cells. Without oxygen, your body cannot obtain

enough energy from food to survive. Excess carbon dioxide pro-

duced as a waste product of aerobic respiration is toxic to cells and

must be removed.

The Path of Air Breathing is only one part of gas exchange. The gases must be

transported by the cardiovascular system and then exchanged at

the cells. All of the organs and tissues that function in this exchange

of gases make up the respiratory system, as shown in Figure 13.

A breath of air enters the respiratory system through the nose or

mouth. Air is made up of many gases. About 21 percent of air is

oxygen gas. Hairs in your nose filter dust and particles out of the

air. Tissues that line the nasal cavity moisten and warm the air.

The Respiratory System Section 3

Objectives

● Summarize the path that

air follows when it enters

the body through the nose

or mouth.

● Describe the role of the rib

muscles and diaphragm in

breathing.

● Describe how breathing

rate is regulated.

● Summarize how oxygen

and carbon dioxide are

transported in the blood.

● Identify three serious

diseases of the lungs.

Key Terms

pharynx

larynx

trachea

bronchus

alveolus

diaphragm

Respiratory System

Diaphragm

Right lung

Bronchi

Pharynx

Trachea

Bronchioles

Larynx

Left lung

Alveoli

Capillaries

Figure 13 Taking in and

exchanging gases. The

respiratory passages, lungs,

and diaphragm make up the

respiratory system.

885


Teaching TipLarynx Point out to studentswhere the vocal cords—larynx—are found. Explain that sound isproduced when air is forced throughthe larynx. Also inform studentsthat laryngitis is simply an inflam-mation of the vocal cords in whichthey lose their ability to vibrate.Hence, people “lose their voice.”

Teaching TipMucus Tell students that a personnormally swallows more than apint of nasal mucus each day, andeven more if he or she has anallergy or infection.

TeachTeach

Newborns In addition to using lungs for thefirst time, a newborn’s heart and cardiovascu-lar system change with the first breath. Anopening, the foramen ovale, lies between theleft and right atria. Another structure, the duc-tus arteriosus, connects the pulmonary arteryto the aorta. Upon inspiration for the firsttime, the lungs are inflated, closing the openingand separating pulmonary circulation from thesystemic circulation.


Calculating theAmount of AirRespired

Skills AcquiredAnalyzing data, calculat-ing, inferring relationships

Teacher’s NotesEnsure that students understandthat units are important indimensional analysis.

Answers to Analysis

1. 15 breaths/min � 0.5 L/breath 7.5 L/min

2. 7.5 L/min � 60 min/hr 450 L/hr

3. Answers will vary but mayinclude that infants havesmaller lungs, a faster heartrate, and a faster metabolism.

x + 6x - 7 - 0

76

0

52

StrategiesStrategiesINCLUSIONINCLUSION

Have students determine the average breath-ing rate for students in their class. The students should record how many breaths(inhale and exhale equals one breath) eachstudent takes for one minute. Have studentsadd each rate and divide by the number ofstudents included in the test to figure theaverage breathing rate. Additionally, studentsmay recruit adult volunteers and determinetheir breath rates and compare the resultswith those taken in class.

• Attention Deficit Disorder • Learning Disabilities

Transparencies

TR J33 Inhalation and Exhalation

From the nose, air passes through a muscular tube in the upper

throat called the (FAIR ingks), which serves as a passage-

way for air and food. The air continues on through a passageway

for air, called the (LAIR ingks), or voice box located in the

neck. A flap of tissue, the epiglottis (ehp uh GLAHT ihs), covers the

opening to the larynx when you swallow food and liquids. This pre-

vents food and liquids from passing into your lungs.

From the larynx the air passes into the (TRAY kee uh), a

long, straight tube in the chest cavity. The trachea, or windpipe,

divides into two smaller tubes, the (BRAHNG kie), which

lead to the lungs. Within the lung, the bronchi (singular, bronchus)

divide into smaller and smaller tubes called bronchioles (BRAHNG

kee ohls). The smallest bronchioles end in clusters of air sacs called

(al VEE uh lie), where gases are actually exchanged. As

shown in Figure 13, each of the 300 million small alveoli is sur-

rounded by a jacket of capillaries. Alveoli increase the surface area

of your lungs to as much as 42 times the surface area of your body.

The cells that line the bronchi and trachea secrete mucus that traps

foreign particles in the air. The mucus is directed upward by cilia to

the epiglottis, where the mucus is swallowed and digested. Microbes

in the mucus are destroyed by acids and enzymes in the stomach.

LungsThe lungs, which are among the largest organs in the body, are sus-

pended in the chest cavity, bounded on the sides by the ribs and on

the bottom by the diaphragm (DIE uh fram). The is a

powerful muscle spanning the rib cage under the lungs, and it aids

in respiration. A double membrane surrounds both lungs. The outer-

most membrane is attached to the wall of the thoracic cavity, and the

inner membrane is attached to the surface of the lungs. Between

both membranes is a small space filled with fluid.

diaphragm

alveoli

bronchi

trachea

larynx

pharynx

Analysis

1. Calculate the volume of air

in liters an adult breathes per

minute if his or her breathing

rate is 15 breaths per minute.

2. Calculate the volume of air

in liters an adult breathes per

hour if his or her breathing

rate is 15 breaths per minute.

3. Critical Thinking

Inferring Conclusions The

breathing rate of an infant is

about 40 breaths per minute.

Why might infants have higher

respiratory rates than adults?

Calculating the Amount of Air Respired Background

Most adults take in about 0.5 L of air with each

breath. The normal breathing rate is about 8 to 15

breaths per minute.

<

x + 6x - 7 - 0

2

8

4930

52

Real Life

The lungs of human

fetuses do not function

until birth.

A fetus’s

umbilical

cord contains

blood vessels

that lead to

and from the

placenta,

which con-

tains fetal

and maternal

capillaries. The O2

in

the mother’s capillaries

diffuses to the fetus’s

capillaries, and the CO2

in the fetus’s capillaries

diffuses into the mother’s

capillaries.

Finding Information

Determine the signal that

stimulates the baby to start

breathing at birth.

886

Answer

Increased CO2 and decreased O2in the baby’s body

Real Life


Teaching TipSpirometer Patients in hospitalsare at risk for lung infectionsbecause they are inactive. If a patientis bedridden, he or she must breathedeeply to get air deep into the lungsand help prevent fluids from accu-mulating there. Inhaled bacteria cangrow easily in warm, moist air andpatients can develop pneumonia.Hospital staff check a patient’s tidalvolume several times a day with aspirometer to ensure enough air isbeing expelled and inhaled.

Brainstorming Lead a class discus-sion on the mechanism of breathing.Ask for volunteers to describe thelocations of the muscles involved in breathing and what happens tothem during inhalation andexhalation. (A volunteer could drawsketches similar to those in Figure 14to illustrate the process.) Ask studentsif the walls of the lungs also havemuscles and, if so, are they involvedin breathing. (No.) Logical

DemonstrationDemonstrate how breathing worksby making a model of the lungsand diaphragm. You will need abell jar, one small balloon, a glasstube, a one-holed rubber stopper, athin rubber sheet, and a rubberband. Attach the deflated balloonto one end of the short glass tubethat has been inserted through theone-holed rubber stopper. Use thestopper to plug the mouth of a belljar, allowing the balloon to hanginside the jar. Use a rubber band tofasten a thin sheet of rubber overthe mouth of the jar. Pull down onthe rubber sheet, and have studentsobserve what happens to the bal-loon. Have students relate theirobservations to inhalation. Releasethe rubber sheet. Have them relatetheir observations to exhalation.Ask students the drawbacks of thismodel. (Chest muscles do not move;only one lung is shown.) VisualLS

LS

SKILL

BUILDER

READINGREADING

Chapter 38 • Circulatory and Respiratory System 887

problems that might arise during surgery or recovery.

Anesthesiologists also work in intensive careunits to help restore critically ill patients to stable condition. Anesthesiologists are involvedin pain management, including diagnosis andtreatment of acute and chronic problems.

The field of anesthesiology is growing andopportunities for employment are excellent.Starting salary will vary by subspecialty and region.

CareerCareerAnesthesiologists Anesthesiologists (anes-thetists) are physicians who complete a four-year college program, four years of graduatemedical training and four more years of anes-thesiology residency. Their primary role in theoperating room is to ensure the patient’s com-fort during surgery and also to make informedmedical judgments to protect the patient. Theseinclude treating and regulating changes in criti-cal life functions, including breathing, heartrate, and blood pressure. These specialistsimmediately diagnose and treat any medical

Breathing Air is drawn into and pushed out of the lungs by the mechanical

process known as breathing. Breathing occurs because of air pres-

sure differences between the lungs and the atmosphere, as shown in

Figure 14. To draw air into the lungs, a process called inhalation, the

rib muscles contract. This draws the rib cage up and out, and the

diaphragm contracts, moving downward. The volume of the chest

cavity increases, which reduces the air pressure within the cavity

below the atmospheric pressure. Because air flows from a high pres-

sure area to a low pressure area, air is drawn into the lungs.

Normal exhalation (breathing out) is a passive process. The rib

cage and diaphragm muscles relax, which returns the rib cage and

diaphragm to their resting position. The relaxation of these muscles

decreases the volume in the chest cavity and increases the air pres-

sure in the lungs. Because the air pressure is now higher in the

lungs than in the atmosphere, air is forced out—from a high pres-

sure area to a low pressure area.

Breathing Rate You took your first breath within moments of being born. Since then,

you have repeated the process more than 200 million times. What

controls how fast or slow you breathe? Receptors in the brain and car-

diovascular system continually monitor the levels of oxygen and

carbon dioxide in the blood. The receptors enable the body to

automatically regulate oxygen and carbon dioxide concentrations by

sending nerve signals to the brain. The brain responds by sending

nerve signals to the diaphragm and rib

muscles in order to speed or slow the rate

of breathing.

It may surprise you to know that

carbon dioxide levels have a greater

effect on breathing than do oxygen lev-

els. For example, if the concentration of

carbon dioxide in your blood increases,

such as during exercise, you respond by

breathing more deeply, ridding your

body of excess carbon dioxide. When the

carbon dioxide level drops, your breath-

ing slows. Factors such as stress, pain,

and fear also influence breathing rate.

The signals that travel from the

breathing center of the brain are not

subject to voluntary control. You cannot

simply decide to stop breathing indefi-

nitely. You can hold your breath for a

while, but even if you lose consciousness

your respiratory control center will take

over and force your body to breathe.

Lung

Rib

Rib cage

muscles

Diaphragm

When the diaphragm contracts,

it moves down and air rushes in.

Inhalation Exhalation

When the diaphragm

relaxes, it moves up

and air is forced out.

The diaphragm and the muscles between the ribs are involved

in the movement of the chest cavity during breathing.

Figure 14 Inhalation and exhalation

887


Reading Organizer Encouragestudents to keep a vocabulary note-book, a stack of vocabulary cards,or some other way of recordingand reviewing unfamiliar vocabu-lary. Each entry should include notonly the correct spelling of theword but also a definition, prefer-ably one in the student’s ownwords. This strategy will be espe-cially beneficial in a chapter likethis one, where students encountermany new terms. Visual

Demonstration

Have a volunteer gently blowthrough a straw into a beaker thatcontains a weak solution of bro-mothymol blue (BTB) and water.The color will change slowly togreen then yellow, indicating thepresence of CO2. Actually, BTB isan indicator of acid. The bicarbon-ate ions and carbonic acid createdby blowing air into the indicatormixture lower the pH of the indica-tor mixture which leads to thecolor change. VisualLS

LS

SKILL

BUILDER

READINGREADING



CulturalAwarenessCulturalAwareness

Saving Lives In 1914, Barrett A. Morgan,an African American, invented the world’sfirst gas mask. Called by many names—breathing device, safety hood, gas inhalator—this clever invention won an award at theSecond International Exposition of Safetyand Sanitation in New York in 1914. Twoyears later it saved the lives of constructionworkers trapped in a smoke-filled tunnelbeneath Lake Erie.

GENERAL

Have students research the hemoglobin molecule anddetermine whether the iron atoms have a valence of2� or 3� and how these different values affect thenumber of oxygen molecules that bind to the ironatoms.


Transparencies

TR J32 O2 and CO2 in the Blood

Gas TransportBreathing is the first step to getting oxygen to the trillions of cells

in your body. When oxygen molecules move from the air into your

alveoli, their journey has just begun, as shown in Figure 15. As

oxygen passes into the plasma of the bloodstream, it is picked up

by red blood cells that carry an iron-containing protein called

hemoglobin.

Oxygen Transport Each hemoglobin molecule contains four atoms of iron. The iron

atoms in the hemoglobin give red blood cells their red color. The

iron atoms bind reversibly with oxygen. Reversible binding means

that at the appropriate time, the oxygen can be released elsewhere

in the body and be taken up by the cells that need it.

Figure 15 summarizes the path of oxygen and carbon dioxide

through the body:

Oxygen from the outside air reaches the lungs.

The oxygen diffuses from the alveoli to the pulmonary capillar-

ies. At the high oxygen levels that occur in the blood within the

lungs, most hemoglobin molecules carry a full load of oxygen.

The oxygen-rich blood then

travels to the heart. The heart

pumps the blood to the tis-

sues of the body.

Oxygen diffuses into the cells

for use during aerobic respi-

ration. In the tissues, oxygen

levels are lower. This causes

the hemoglobin to release its

oxygen.

In tissues, the presence of

carbon dioxide produced by

cellular respiration makes the

blood more acidic and causes

the hemoglobin molecules to

assume a different shape, one

that gives up oxygen more eas-

ily. The carbon dioxide diffuses

from the cells to the blood.

Most of the carbon dioxide

travels to the heart as bicar-

bonate (HCO3–) ions.

The heart pumps the blood to

the lungs. In the lungs, carbon

dioxide is released in its

gaseous form to the alveoli.

The carbon dioxide is expelled.

O2

O2CO2

CO2

CO2

CO2

CO2

HCO3–

HCO3–

HCO3–

O2

O2

O2

O2

O2

Cells

Systemic

arteries

Systemic

veins

Pulmonary

arteries

Pulmonary

vein

Heart

Alveoli

O2 diffuses

into blood.

O2 is inhaled.

Red blood cells

carry O2.

CO2 diffuses to the blood.

CO2 is exhaled.

CO2 is released

in its gaseous

form to the

alveoli.

O2 diffuses into cells.

Most CO2travels in the

blood as

bicarbonate

ions (HCO3–).

Figure 15 O2and CO

2

transport in the blood.

Hemoglobin molecules inside

red blood cells transport

oxygen, while most carbon

dioxide is transported as bicar-

bonate ions in the plasma.

888


Teaching TipRespiratory Control Center Tellstudents that changes in blood gasand pH levels trigger changes in therate of respiration. Chemoreceptorsin the cartotid arteries (on eitherside of the neck) and in the aortadetect CO2 and O2 concentrationin the blood as well as blood pH.When these receptors detect highCO2 levels, low O2 levels, or lowblood pH, they send signals to therespiratory control center locatedin the medulla oblongata of thebrain. In addition, other receptorsthat detect high CO2 levels and lowpH in the cerebrospinal fluid of thebrain send signals to the respiratorycontrol center. When the respira-tory control center receives thesesignals, it sends signals to the mus-cles involved in breathing. Themuscles contract more frequently,which results in an increase in therespiration rate. This, in turn, low-ers CO2 levels, raises O2 levels, andraises blood pH.

Chapter 38 • Circulatory and Respiratory System 889

Modeling the Roleof Bicarbonate inHomeostasis

Skills AcquiredInferring, analyzing

Teacher’s NotesCarefully review the chemicalequations on this page.

Answers to Analysis

1. A becomes acidic; B becomesbasic.

2. sodium bicarbonate, H2CO3–

3. H2O + CO2 ª¢H2CO3 ª¢HCO3

– + H+

4. It buffered the carbonic acid.

5. Most of the CO2 in the bloodtravels as bicarbonate ions.

results primarily from the action of sunlighton hydrocarbons and nitrogen oxides emittedduring fuel combustion. Particulate matter airpollution is a mixture of substances thatincludes particles, dust, and aerosols. Principalsources of nitrogen dioxide are automobilesand fuel combustion by electric utilities. Sulfurdioxide is formed when fuel containing sulfur(mainly coal and oil) is burned. Major sourcesof sulfur dioxide are electric utilities andindustrial fuel combustion.

Nearly 335,000 Americans die each year fromlung disease, which is the third leading causeof death in the United States. During the lastten years, the death rate for lung disease hasrisen faster than that of any of the top fivecauses of death.

Air pollution contributes to lung disease,including respiratory tract infections, asthma,emphysema, and lung cancer. The major types of air pollution include excess ozone,particulate matter, nitrogen dioxide, and sul-fur dioxide. Excess ozone in the atmosphere

ENVIRONMENTAL SCIENCEENVIRONMENTAL SCIENCECONNECTIONCONNECTION

Carbon Dioxide Transport At the same time that the red blood cells are unloading oxygen to

tissues, they are also taking in carbon dioxide from the tissues.

Carbon dioxide is carried by the blood in three forms:

1. About 7 percent of CO2 is dissolved in the blood plasma.

2. About 23 percent of CO2 is attached to hemoglobin molecules

inside red blood cells.

3. The majority of CO2, 70 percent, is carried in the blood as bicar-

bonate ions.

How is CO2 carried as bicarbonate ions? In the presence of a cer-

tain enzyme, carbon dioxide combines with water to form carbonic

acid, H2CO3. This is shown in the equation below. The carbonic acid

then breaks up to form a bicarbonate ion, HCO3–, and a hydrogen

ion, H+:

H2O 1 CO2←→ H2CO3

←→ HCO3

–1 H+

Thus, most of the CO2 travels in the blood as bicarbonate ions. The

hydrogen ions make the blood more acidic. When the blood reaches

the lungs, the series of reactions is reversed:

HCO3–

1 H+ ←→ H2CO3

←→ H2O 1 CO2

A bicarbonate ion combines with a hydrogen ion to form carbonic

acid, which in turn forms CO2 and water. The CO2 diffuses out of

the capillaries into the alveoli and is exhaled into the atmosphere.

Modeling the Role of Bicarbonate in HomeostasisYou can use pH indicator paper, water, and baking soda to

model the role of bicarbonate ions in maintaining blood pH

levels in the presence of carbon dioxide.

Materials

two 250 mL beakers, 250 mL distilled water, 2.8 g baking soda,

glass stirring rod, 4 strips of wide-range pH paper, 2 drinking straws

Procedure

1. Label one beaker A and

another B. Fill each beaker

halfway with distilled water.

2. Add 1.4 g of baking soda to

beaker B, and stir well.

3. Test and record the pH of the

contents of each beaker.

4. Gently blow through a straw,

into the water in beaker A.

Test and record the pH of the

resulting solution.

5. Repeat step 4 for beaker B.

Analysis

1. Describe what happened to

the pH in the two beakers

during the experiment.

2. State the chemical name for

baking soda.

3. Propose the chemical reac-

tion that might have caused a

change in pH in beaker A.

4. Summarize the effect the

baking soda had on the pH

of the solution in beaker B

after blowing.

5. Critical Thinking

Applying Information

Relate what happened in

beaker B to what occurs in

the bloodstream.

889


ReteachingDraw a simplified version ofFigure 15 on the board. Have stu-dents close their books, and askvolunteers to draw arrows showingthe directions of circulation and gasexchange. Have other volunteersannotate the diagram with briefstatements that describe key events.

Visual

Quiz1. The ________ in the lungs are the

sites of oxygen uptake into theblood. (alveoli)

2.The muscles involved in breath-ing are the muscles of the________ and the ________ . (rib cage, diaphragm)

3. Oxygen is carried in the bloodbound to ________ inside________ cells. (hemoglobin, red blood)

4. Carbon dioxide is carried in theblood primarily in the form of________ .(bicarbonate ions)

AlternativeAssessmentHave students draw pictures oflungs during inhalation and exhala-tion. Students should use labeledarrows to show the direction ofdiaphragm and rib muscle movementand oxygen and carbon dioxidemovement.

GENERAL

GENERAL

LS

CloseClose


1. mouth, pharynx, larynx, trachea, bronchi,bronchioles, and alveoli

2. The rib muscles contract, drawing the rib cageup and out; the diaphragm moves down.

3. Levels of oxygen and carbon dioxide in theblood regulate the rate of breathing. Increasedblood carbon dioxide concentration triggersthe brain to send a message to the diaphragmand rib muscles that speeds up the rate ofbreathing.

4. Seventy percent of the carbon dioxide in theblood is carried as bicarbonate ions.

5. Yes, any physical effort increases the oxygenneeded and energy required to breathe.

6. A. Incorrect. The function of the larynx is toproduce sound. B. Correct. The alveoli are airsacs where gas exchange takes place.C. Incorrect. The trachea transports air to thebronchi. D. Incorrect. The bronchi are tubesthat lead to the lungs.


Respiratory Diseases Respiratory diseases affect millions of Americans. A chronic pul-

monary—or lung—disease is one for which there is no cure.

Asthma Asthma (AZ muh) is a chronic condition in which the bronchioles

of the lungs become inflamed, because of their sensitivity to certain

stimuli in the air. The bronchial walls tighten and extra mucus is

produced, causing the airways to narrow. In severe asthma attacks,

the alveoli may swell enough to rupture. Stressful situations and

strenuous exercise may trigger an asthma attack. Left untreated,

asthma can be deadly. Fortunately, prescribed inhalant medicines

may help to stop an asthma attack by expanding the bronchioles.

People of all ages can have asthma.

Emphysema Emphysema (ehm fuh SEE muh) is a chronic pulmonary disease

resulting from a chemical imbalance that destroys elastic fibers in

the lungs. Normally, these elastic fibers allow the lungs to expand

and contract. Emphysema begins with the destruction of alveoli. Dam-

age to the alveoli is irreversible and results in constant fatigue and

breathlessness. Severely affected individuals must breathe from tanks

of oxygen in order to live. Smoking is the cause of up to 90 percent of

emphysema cases. Emphysema affects millions of lives annually.

Lung Cancer Lung cancer is one of the leading causes of death in the world today.

As shown in Figure 16, cancer is a disease characterized by abnormal

cell growth. In the United States alone, about 28 percent—155,000—

of all cancer deaths each year are attributed to lung cancer. Smoking

is the major cause of lung cancer. Once cancer is detected, the

affected lung is sometimes removed surgically. Even with such dras-

tic measures, lung cancer usually is not curable. About 15 percent of

lung cancer victims live more than 5 years after diagnosis.

Sequence the path a breath of air follows throughthe respiratory system. (Begin with air that entersthrough the nose or mouth.)

State the direction that the diaphragm and ribcage move to cause inhalation.

Name the main factor that regulates the rate ofbreathing.

Evaluate the role that bicarbonate plays intransporting carbon dioxide in the blood.

Critical Thinking Justifying Conclusions

Would a person with emphysema have troubleclimbing stairs? Explain.

Gases are exchangedbetween the blood and inhaled air in the

A larynx. C trachea.

B alveoli. D bronchi.


Section 3 Review

Figure 16 Healthy lungs

and cancerous lungs. The

top photo shows a healthy

lung. The bottom photo

shows a cancerous lung

which contains cells that divide

uncontrollably.

890


AlternativeAssessmentHave students make a board gamewith questions about normal andabnormal function of the circula-tory and respiratory systems.

GENERAL


• Science Skills Worksheet

• Critical Thinking Worksheet

• Test Prep Pretest

• Chapter Test GENERAL

GENERAL

GENERAL


such as

largest are

blood vessels

capillaries veins

venae cavae

largest is

aorta

lymphatic system

Circulatory system

is composed of

arteries

has

atria ventricles

systemiccirculation

pulmonarycirculation

heart

regulates

Remind students that the chemicalchange of H2CO3 into HCO3

2

1 H1

(andvice versa) is an example of an oxida-tion/reduction reaction, that is, electronsare shifted from one substance to anoth-er. Have advanced students write thehalf reactions for this chemical reactionand identify the substances oxidized andreduced.


Answer to Concept Map

The following is one possible answer to Performance Zone item 15.

Key Concepts

Study CHAPTER HIGHLIGHTS

ZONE

Key Terms

Section 1

cardiovascular system (872)

artery (873)

capillary (873)

vein (873)

valve (874)

lymphatic system (875)

plasma (876)

red blood cell (876)

anemia (877)

white blood cell (877)

platelet (877)

ABO blood group system (878)

Rh factor (879)

Section 2

atrium (881)

ventricle (881)

vena cava (881)

aorta (882)

coronary artery (882)

sinoatrial node (882)

blood pressure (882)

pulse (883)

heart attack (884)

stroke (884)

Section 3

pharynx (886)

larynx (886)

trachea (886)

bronchus (886)

alveolus (886)

diaphragm (886)

The Circulatory System

● The human cardiovascular system is made up of blood

vessels, blood, and the heart, which together function to

transport materials, remove wastes, and distribute heat.

● Arteries carry blood away from the heart. Materials are

exchanged at the capillaries. Veins contain valves and carry

blood back to the heart. Fluids not returned to the capillaries

are picked up by lymphatic vessels.

● Blood consists of plasma (water, metabolites, wastes, salts,

and proteins), red blood cells, white blood cells, and platelets.

● Blood types are defined by the presence or absence of

complex carbohydrates on the surface of red blood cells.

The Heart

● The right side of the heart receives oxygen-poor blood from

the body and circulates it to the lungs. In the lungs, gases

are exchanged. The left side of the heart receives oxygenated

blood from the lungs and circulates it to the rest of the body.

● Atria receive blood entering the heart. Ventricles pump

blood away from the heart.

● Contraction of the heart is initiated by the sinoatrial node.

The health of the cardiovascular system can be monitored by

measuring blood pressure, electrical impulses, and pulse rate.

● Blockages in blood vessels can lead to heart attacks or strokes.

The Respiratory System

● A series of tubes and bunched air sacs (alveoli) take in

oxygen and remove carbon dioxide.

● Breathing is caused by pressure changes within the chest cavity.

● The concentration of carbon dioxide in the blood is the most

critical factor affecting a person’s breathing rate and depth.

● Oxygen is transported to tissues by combining with hemo-

globin molecules inside red blood cells. Most carbon dioxide

is transported to the lungs as bicarbonate ions.

● Asthma, emphysema, and lung cancer limit lung function.

3

2

1

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Understanding Key Ideas

1. b

2. c

3. a

4. c

5. b

6. c

7. d

8. There are relatively few bloodtypes shared by all humans, whileDNA fingerprints of humans varyfrom individual to individual.

9. Thinner blood reduces thechances of clot formation.

10. The answer to the concept map isfound at the bottom of the previ-ous page.

Critical Thinking

11. Clotting ability is most likelydiminished because platelets willnot stick as readily.

12. It will decrease because the run-ner will not get as much oxygenas obtained at sea level.

13. Constriction of blood vessels con-serves heat. Dilation of bloodvessels increases heat dissipation.

14. Answers will vary but shouldinclude fish, fresh fruits, vegeta-bles, and foods low in saturatedfat.

Alternative Assessment

15. Respiratory therapists treatpatients who have breathing diffi-culties. Respiratory therapists userespirators and oxygen tents.They develop treatment programsfor long-term care, and theyoperate and maintain oxygendelivery equipment. Most attendtwo years of college with anemphasis on math and science

courses. Respiratory therapists must be pro-fessionally certified. Many are employed byhospitals or physicians. The growth prospectsof the field are excellent. Starting salary willvary by region.

Section Questions

1 1, 2, 8, 10, 11, 13

2 3, 6, 7, 9, 14

3 4, 5, 12, 15

Assignment Guide


CHAPTER 38

Understanding Key Ideas

1. Lymphatic vessels a. transport blood.b. return fluid to the blood.c. produce antibodies.d. control blood clotting.

2. What type of blood contains A antibodies(but not B antibodies) in the plasma andlacks Rh antigens? a. AB negativeb. A positivec. B negatived. O positive

3. Blood in the pulmonary veins is a. oxygen-rich. c. oxygen-poor.b. iron-poor. d. calcium-rich.

4. The diaphragm contracts and the pressurein the chest cavity decreases during a. bronchitis. c. inhalation.b. exhalation. d. asthma attacks.

5. Breathing rate will automatically increasewhen a. blood pH is high.b. the amount of carbon dioxide in theblood increases.

c. blood acidity decreases.d. hemoglobin is unloaded.

6. Which organ receives the richest oxygensupply from blood returning from thelungs? a. stomach c. heartb. brain d. kidney

7. Which is not a factor that contributes to chronic coronary disease? a. a diet rich in fatb. unmanaged stress c. cigarette smokingd. vigorous exercise

8. Why does DNA testing ofblood lead to a more reliable match ofblood to suspect than does blood typing?

9. One of the effects ofaspirin is that it thins the blood. Why isaspirin sometimes prescribed for people atrisk for heart attack?

10. Concept Mapping Make a conceptmap that outlines the path of bloodthrough the body. Try to include the follow-ing terms in your map: artery, capillary,vein, lymphatic system, pulmonary circula-tion, systemic circulation, atrium, ventricle,aorta, and vena cava.

Critical Thinking

11. Forming Reasoned Opinions The frequencyof blood clots and heart attacks is muchlower among the Inuit, the nomadic huntersof the North American Arctic, than it isamong other North Americans. This differ-ence is credited to fish oils in the Inuit dietthat cause blood platelets to be more slippery.How might slippery platelets affect the clot-ting ability of the Inuit’s blood?

12. Evaluating Results As altitude increases,the atmosphere becomes thinner. When arunner who trained at sea level competes ata location 500 m above sea level, how willhis or her performance compare with his orher training performance?

13. Inferring Function How is body tempera-ture regulated by blood vessel diameter?

14. Finding Information Use the media centeror Internet resources to find out whichfoods are recommended as foods that prevent heart disease.

Alternative Assessment

15. Career Connection Respiratory

Therapist Research the field of respiratorytherapy, and write a report on your find-ings. Your report should include a jobdescription, training required, kinds ofemployers, growth prospects, and starting salary.

PerformanceZONE

CHAPTER REVIEW

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Standardized Test Prep

Understanding ConceptsDirections (1–5): For each question, write ona separate sheet of paper the letter of thecorrect answer.

1 Which part of the heart is the pacemaker?A. coronary sinusB. inferior vena cavaC. left ventricleD. sinoatrial node

2 In what organ is carbon dioxide releasedin its gaseous form?F. diaphragm H. lungG. heart I. muscle

3 Which of the following is a disease inwhich the elastic fibers in the alveoli aredestroyed?A. arteriosclerosisB. asthmaC. atherosclerosisD. emphysema

4 Which chamber of the heart sends bloodto the lungs?F. left atrium H. left ventricleG. right atrium I. right ventricle

5 Which of the following is a factor that contributes to heart attacks and strokes?A. unmanaged stressB. regular physical activityC. avoiding cigarette smokeD. diet high in unsaturated fats

Directions (6): For the following question,write a short response.

6 What role do surface markers play inblood typing?

Reading SkillsDirections (7): Read the passage below.Then answer the question.

Dr. Charles Drew (1904–1950) was anAfrican-American physician who worked atColumbia University in New York. Amonghis many accomplishments was the develop-ment of a way to keep blood plasma fresh.He separated the plasma from the red bloodcells and froze these parts of blood sepa-rately. Dr. Drew also helped save many livesby starting the first blood bank.

7 Which component of blood allows it tocarry oxygen to tissues in the body?F. plasmaG. plateletsH. red blood cellsI. white blood cells

Interpreting GraphicsDirections (8): Base your answer to question8 on the graph below.

Daily Salt Intake and

Blood Pressure in Humans

8 What conclusion can be drawn from thechart?A. A person can reduce hypertension byconsuming more salt.

B. A daily intake of 10 g or less is associated with a risk to health.

C. Raising one’s systolic pressure leads to a greater appetite for salt.

D. Increasing one’s salt intake leads to an increased systolic pressure.

Systolic pressure (

mm

Hg

)

0

110

120

130

140

160

170

150

10 20 30

Daily salt intake (g)

Test

When using a graph to answer a question, read the

graph’s title and the labels on the graph's axes. For

graphs that show a change in some variable over

time, keep in mind that the steepness and direction

of a curve indicate the relative rate of change at a

given point in time.

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Question 5 Answer A is the cor-rect choice. Unmanaged stress,lack of physical exercise, diets highin saturated fats, and cigarettesmoking are factors that con-tribute to heart attacks andstrokes. Answer B is incorrectbecause regular physical activityreduces risk for these problems.Answer C is incorrect becauseavoiding cigarette smoke reducesrisk for these problems. Answer Dis incorrect because a diet high insaturated, not unsaturated, fatsincreases the risk for these problems.

Question 6 The letters of bloodtypes refer to complex carbohy-drates on the surface of red bloodcells that act as antigens.

Question 7 Answer H is the cor-rect choice. Red blood cells con-tain hemoglobin, a protein thatbinds with oxygen. Answer F isincorrect because plasma is the liq-uid portion of blood. The oxygendissolved in plasma is not signifi-cant enough to provide tissueswith their oxygen needs. Answer is incorrect because platelets arecell fragments important to clot-ting, but they do not transportoxygen. Answer I is incorrectbecause white blood cells defendthe body against disease, but donot transport oxygen.

Item 8 Answer D is the correctchoice. Answer A is incorrectbecause consuming more saltmakes hypertension worse. AnsweB is incorrect because a dailyintake of 10 g or less does notincrease blood pressure above nor-mal nor cause damage in any otherway to the cardiovascular system.Answer C is incorrect becauseincreased systolic blood pressuredoes not itself increase a person’sappetite for salt.

Answers

1. D

2. H

3. D

4. I

5. A

6. Blood types are named for the antigens presenton blood cell surfaces.

7. H

8. D

Standardized Test Prep


38 circulatory and€¦ · systems play major roles in these functions. the circulatory system,...

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