transport and exchange 1: blood and breath

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

BIOLOGYA GUIDE TO THE NATURAL WORLD

FOURTH EDITION

DAVID KROGH

Transport and Exchange 1:Blood and Breath

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings.

29.1 The Cardiovascular System


The Cardiovascular System

• The human cardiovascular system is a fluid transport system that consists of the heart, all the body’s blood vessels, the blood, and the bone marrow tissue in which red blood cells are formed.



• This system transports substances both to and from the body’s cells.

• Such substances include oxygen, carbon dioxide, nutrients, vitamins, hormones, waste products, and immune system cells and proteins.


Transport and Exchange System

Figure 29.1

Digestive systemtransforms food into a formthat can be transportedthroughout the body.

Urinary systemfilters bodily fluids, removeswaste while conservingwater and other materials.

Cardiovascular systemtransports materials to andfrom all other systems.

Respiratory systemmoves O2 into, andCO2 out of the body.


29.2 The Composition of Blood


The Composition of Blood

• Blood has two primary components: formed elements and blood plasma.

• Formed elements are blood cells and cell fragments.

• Blood plasma is the fluid portion of blood in which the formed elements are suspended.



• There are three kinds of formed elements:– red blood cells– white blood cells– platelets



Figure 29.2

blood sample

formedelements

plasma55%

99.9%0.1%

45%

Formed elements Plasma

Red blood cells White blood cells Platelets

Red blood cellsWhite blood cellsPlatelets

92%7%1%

WaterPlasma proteinsOther solutes



• Red blood cells carry oxygen to, and carbon dioxide from, every part of the body.

• White blood cells are central to the immune system.

• Platelets are small fragments of cells that are important in the blood-clotting process.


Transport Cells

Figure 29.3


Plasma

• Blood plasma is 92 percent water, but it also contains other materials, including proteins.


Plasma

• There are three primary classes of plasma proteins:– Albumins, which transport hormones and fatty

acids.– Fibrinogen, which aids in blood clotting.– Globulins, which aid the immune system and serve

as transport proteins.


Transport Proteins

• Two transport proteins are important in the health of the heart.

• Low-density lipoproteins (LDLs) carry lipids to bodily tissues from the liver and small intestines.

• High-density lipoproteins (HDLs) carry lipids from these tissues to the liver.


Plasma

• Other plasma compounds include nutrients, wastes, hormones, and electrolytes.


29.3 Blood Vessels


Blood Vessels

• Blood vessels carrying blood away from the heart are arteries; blood vessels returning blood to the heart are veins.


Blood Vessels

• The smallest blood vessels, the capillaries, connect the arteries with the veins.


Blood Vessels

Figure 29.4

epithelium

artery capillary

veinmuscle

connectivetissue

epithelium

muscle

connectivetissue


Blood Vessels

• Arteries and veins are always made of three distinct layers of tissue.

• The middle layer is muscle that allows arteries and veins to widen or constrict in diameter.


Blood Vessels

• Capillaries, conversely, are composed of only a single layer of cells.

• This allows the movement of blood-borne materials into and out of them along their length.


29.4 The Heart and Blood Circulation


The Heart and Blood Circulation

• The heart’s contractions propel blood out to the various tissues of the body.



• Two blood circulation loops exist in the body. • The first loop is the pulmonary circulation, in

which blood circulates between the heart and the lungs (with the result that blood is oxygenated).



• The second loop is the systemic circulation, in which blood circulates between the heart and the rest of the body.

• The result is that needed materials are transported to and from all parts of the body.



Figure 29.5

pulmonarycirculation(to lungs)

systemiccirculation

(to all tissues)

superiorvena cava

inferiorvena cava

The left side of theheart pumpsoxygenated blood tothe entire body.

pulmonaryarteriespulmonaryveins

systemicarteries

systemicveins

The right side ofthe heart pumps

deoxygenatedblood to the lungs.

The pulmonary and systemic circulation networks The circulation of blood through the heart

Deoxygenatedblood enters theright atriumthrough the superiorand inferior venacavae.

The right atrium pumpsblood into theright ventricle, whichcontracts, pumpingblood to the lungs.

Blood is deliveredto the lungs via thepulmonary arteries.

Oxygenated bloodreturns from thelungs through thepulmonary veins.

Blood thenmoves into theleft atrium whichpumps it into theleft ventricle.

Powerful contractionsof theleft ventricle forceblood into the aorta.

From theaorta, blood isdistributed to therest of the body.



• The human heart contains four muscular chambers:– Two for pulmonary circulation (the right atrium and

right ventricle).– Two for systemic circulation (the left atrium and

left ventricle).



• A series of valves that open and close ensures that blood flows only one way through the heart.



PLAY Animation 29.1: The Cardiovascular System


29.5 What is a Heart Attack?


Heart Attacks

• About half of all deaths in the United States today are caused by the blockage of one or more of the coronary arteries that supply heart tissue with blood.


Heart Attacks

• Such blockages generally are caused by a buildup of low-density lipoprotein (LDL) molecules in a coronary artery, followed by an immune system reaction to these LDLs and formation of a blood clot in the artery.


Heart Attacks

• A heart attack occurs when this process results in the complete blockage of a coronary artery, which cuts off the blood supply to groups of cells within the heart, thus killing them.


Critical Vessels

Figure 29.6

superiorvena cava

rightcoronary

artery

left maincoronaryartery

left anteriordescendingcoronaryartery

pulmonaryartery

aorta

site ofblockage

damagedheart muscle

blood clot core ofoxidized

LDLmolecules


29.6 Distributing the Goods: The Capillary Beds


The Capillary Beds

• Arteries near the heart branch into smaller arterioles, which feed into the delivery vehicles of the cardiovascular system, the capillary beds.


Capillary Beds

• The capillary beds then feed back into the body’s system of veins that returns blood to the heart.


Capillary Beds

Figure 29.7

artery

capillary bed

vein

epithelial cells ofcapillary wall

tissuecells

interstitial fluid

CO2 wastes

venulearteriole

O2 glucose


Capillary Beds

• Materials needed by the body’s tissues move out of the capillaries and into the interstitial fluid that surrounds both the capillaries and nearby cells.

• Meanwhile, carbon dioxide and wastes from these cells flow into capillaries from the interstitial fluid.


Capillary Beds

• The movement of all these substances is aided by their concentration gradients.

• They move from areas of their higher concentration to areas of their lower concentration.

• The movement of water is driven in two directions by two opposing forces.


Capillary Beds

• At the arterial end of the capillary beds, blood pressure tends to drive water out of the capillaries.

• But at the venous end of the beds, osmosis overcomes the force of blood pressure and pulls most of this water back into the capillaries.


Capillary Beds

• Blood pressure is at low levels by the time blood has moved through the capillaries.


Capillary Beds

• Blood returns to the heart through the contraction of skeletal muscles, which squeeze the veins in a way that moves the venous blood toward the heart.

• A system of valves in the veins ensures that this movement is one way—toward the heart.


One-Way Flow to the Heart

Figure 29.8

Valves allow bloodto go forward . . .

. . . but notbackward

valveopen

valveopen

valveclosed

valveclosed

musclescontracted

musclesrelaxed


29.7 The Respiratory System


The Respiratory System

• The central function of the respiratory system is to capture oxygen and to dispose of carbon dioxide.

• It also aids in controlling pH balance in the bloodstream and in producing sounds for speaking.



• Respiration can be defined as the exchange of gases between the atmosphere outside the body and the cells within it.



• The respiratory system includes:– the lungs, the nose, nasal cavity, and sinuses– the pharynx (upper throat)– the larynx (voice box)– the trachea (windpipe)– the conducting passageways, called bronchi and

bronchioles, that lead to the lungs



• The lungs themselves are largely composed of the tiny hollow sacs, called alveoli.

• Alveoli lie at the end of each bronchiole and they are the air exchange chambers of the body.



Figure 29.9

sinuses

pharynx

esophagus

right lung

diaphragm

nasal cavity

trachealeft lungleft bronchusbronchioles

veinartery

alveolus

capillary network

larynx

Anatomy of the lungs

The structure of alveoli

A bronchiole and its alveoli



• The enormous surface area of the alveoli and their associated capillaries is used for the exchange of oxygen and carbon dioxide.


29.8 Steps in Respiration


Steps in Respiration

• The first step in respiration is breathing or ventilation, meaning the physical movement of air into and out of the lungs.


Ventilation

Figure 29.10

inhalation exhalation

respiratorycycle

lungs

ribs

diaphragm

Elevation of rib cageand contraction ofdiaphragm decreasepressure in the lungs,causing air to flow in.

Depression of ribcage and elevationof diaphragmincrease pressurein lungs causingair to flow out.



• Once in the lungs, oxygen diffuses across the thin wall of an alveolus into an adjacent capillary and binds with hemoglobin protein in red blood cells.



• Oxygen then moves with the blood cells to the heart.

• The heart pumps the blood to body tissues, where the oxygen diffuses into the interstitial fluid and then into nearby cells.



• The carbon dioxide produced in the body’s cells moves into nearby capillaries, to be carried to the lungs.


Gas Exchange in the Body

Figure 29.11

O2

capillary

tissue cell

CO2

air outair in

O2

alveolus inlung

CO2



• All the oxygen loaded into red blood cells binds initially with the hemoglobin in them.

• Carbon dioxide is transported both within red blood cells and in blood plasma.



PLAY Animation 29.2: The Respiratory System

transport and exchange 1: blood and breath

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