transportation. section 1: blood cardiovascular system – includes: fluid (blood) – includes ~75...

Transportation

Section 1: Blood

• Cardiovascular system– Includes:• Fluid (blood)

– Includes ~75 trillion cells

• Series of conducting hoses (blood vessels)• Pump (heart)

VeinArtery

Capillaries

Heart

The Components of the Cardiovascular System

THE HEART propels blood and maintains blood pressure.

BLOOD VESSELS

Capillaries

Arteries

Veins

BLOOD

distribute blood around the body.

permit diffusion between blood andinterstitial fluids.

carry blood away from the heart to thecapillaries.

return blood from capillaries to theheart.

distributes oxygen, carbon dioxide, andblood cells; delivers nutrients and hormones;transports waste products; and assists intemperature regulation and defense against disease.

Figure 17 Section 1 1

Section 1: Blood

• Functions of blood– Transportation of dissolved gases, nutrients,

hormones, and metabolic wastes– Regulation of the pH and ion composition of

interstitial fluids– Restriction of fluid loss at injury sites– Defense against toxins and pathogens– Stabilization of body temperature

Module 17.1: Blood components

• Blood– Is a fluid connective tissue– About 5 liters (5.3 quarts) in body

• 5–6 in males, 4–5 in females (difference mainly body size)– Consists of:

• Plasma (liquid matrix)• Formed elements (cells and cell fragments)

– Properties• Temp is roughly 38°C (100.4°F)• Is 5× more viscous than water (due to solid components)• Is slightly alkaline (average pH 7.4)


• Whole blood– Term for removed blood when composition is

unaltered• May be fractionated or separated

– Plasma» 46%–63% of blood volume

– Hematocrit (or packed cell volume [PCV])» Percentage of whole blood contributed by formed elements

(99% of which are red blood cells)» Average 47% for male (range 40%–54%)» Average 42% for female (range 37%–47%)


• Plasma– Composition resembles interstitial fluid in many ways

• Exists because exchange of water, ions, and small solutes• 92% water• 7% plasma proteins• 1% other solutes

– Primary differences• Levels of respiratory gases (oxygen and carbon dioxide)• Concentrations of dissolved proteins (cannot cross capillary

walls)


• Plasma proteins– In solution rather than as fibers like other

connective tissues– Each 100 mL has ~7.6 g of protein• ~5× that of interstitial fluid

– Large size and globular shapes prevent leaving bloodstream

– Liver synthesizes >90% of all plasma proteins


• Plasma proteins (continued)– Albumins

• ~60% of all plasma proteins• Major contributors to plasma osmotic pressure

– Globulins• ~35% of all plasma proteins• Antibodies (immunoglobulins) that attack pathogens• Transport globulins that bind ions, hormones, compounds

– Fibrinogen• Functions in clotting and activate to form fibrin strands

– Many active and inactive enzymes and hormones


• Plasma solutes– Electrolytes

• Essential for vital cellular activities• Major ions are Na+, K+, Ca2+, Mg2+, Cl–, HCO3

–, HPO4–, SO4

2–

– Organic nutrients• Used for cell ATP production, growth, and maintenance• Includes lipids, carbohydrates, and amino acids

– Organic wastes• Carried to sites of breakdown or excretion• Examples: urea, uric acid, creatinine, bilirubin, NH4

+

Figure 17.1 1

Wholeblood

consists of

Plasma(46–63%)

Formedelements(37–54%)


• Formed elements– Platelets

• Small membrane-bound cell fragments involved in clotting– White blood cells (WBCs)

• Also known as leukocytes (leukos, white + -cyte, cell)• Participate in body’s defense mechanisms• Five classes, each with different functions

– Red blood cells (RBCs)• Also known as erythrocytes (erythros, red + -cyte, cell)• Essential for oxygen transport in blood

Module 17.1 Review

a. Define hematocrit.

b. Identify the two components constituting whole blood, and list the composition of each.

c. Which specific plasma proteins would you expect to be elevated during an infection?

Module 17.2: Red blood cells

• RBCs in blood– Most numerous cell type in blood• Roughly 1/3 of all cells in the body

– Red blood cell count (standard blood test) results• Adult males: 4.5–6.3 million RBCs/1 µL or 1 mm3 of whole

blood• Adult females: 4.2–5.5 million RBCs/1 µL or 1 mm3 of

whole blood• One drop = 260 million RBCs


• RBC characteristics– Biconcave disc– Average diameter ~8 µm– Large surface area-to-volume ratio• Greater exchange rate of oxygen

– Can form stacks (rouleaux)• Facilitate smooth transport through small vessels

– Are flexible• Allow movement through capillaries with diameters

smaller than RBC (as narrow as 4 µm)

Figure 17.2 1

Stained blood smear LM x 450

Figure 17.2 2

The size and biconcave shape of an RBC

RBCs Colorized SEM x 1800

7.2–8.4 μm

0.45–1.16 μm 2.31–2.85 μm

Figure 17.2 3

The advantages of the biconcave shape of RBCs

Functional Aspects of Red Blood Cells

• Large surface area-to-volume ration. Each RBC carries oxygen bound to intracellular proteins, and that oxygen must be absorbed or released quickly as the RBC passes through the capillaries. The greater the surface area per unit volume, the faster the exchange between the RBC’s interior and the surrounding plasma. The total surface area of all the RBCs in the blood of a typical adult is about 3800 square meters, roughly 2000 times the total surface area of the body.

• RBCs can form stacks. Like dinner plates, RBCs can form stacks that ease the flow through narrow blood vessels. An entire stack can pass along a blood vessel only slightly larger than the diameter of a single RBC, whereas individual cells would bump the walls, bang together, and form logjams that could restrict or prevent blood flow.

• Flexibility. Red blood cells are very flexible and can bend and flex when entering small capillaries and branches. By changing shape, individual RBCs can squeeze through capillaries as narrow as 4 μm.

Sectional view of capillaries LM x 1430

Red blood cell (RBC)

Nucleus of endothelial cell

Blood vessels (viewedin longitudinal section)

Rouleaux(stacks of RBCs)


• RBC characteristics (continued)– Lose most organelles including nucleus during development

• Cannot repair themselves and die in ~120 days– Contain many molecules (hemoglobin) associated with

primary function of carrying oxygen• Each cell contains ~280 million hemoglobin (Hb) molecules• Normal whole blood content (grams per deciliter)

– 14–18 dL (males), 12–16 dL (females)

• ~98.5% of blood oxygen attached to Hb in RBCs– Rest of oxygen dissolved in plasma


• Hemoglobin– Protein with complex quaternary structure– Each molecule has 4 chains (globular protein subunits)

• 2 alpha (α) chains• 2 beta (β) chains

– Each chain contains a single heme pigment molecule• Each heme (with iron) can reversibly bind one molecule of oxygen

– Forms oxyhemoglobin (HbO2) (bright red)

» Deoxyhemoglobin when not binding O2 (dark red)

Figure 17.2 4

Figure 17.2 5

The quaternary structureof hemoglobin

α chain 1

β chain 2

β chain 1

α chain 2

Heme

Figure 17.2 6

The chemical structureof a heme unit

Heme

Module 17.2 Review

a. Define rouleaux.

b. Describe hemoglobin.

c. Compare oxyhemoglobin with deoxyhemoglobin.

Section 1: Heart Structure

• Location of the heart– Near anterior chest wall, directly posterior to

sternum– Center lies slightly to the left of midline– Entire heart is rotated slightly left

Section 1: Heart Structure

• Gross anatomy– Base (superior surface where major vessels attach)– Apex (inferior pointed tip)– Borders• Superior border (formed by base) • Right border (formed by right atrium)• Left border (formed by left ventricle and small part of left

atrium)• Inferior border (formed mainly by inferior wall of right

ventricle)

The location of the heartin the chest cavity

1 1

2 2

3 3

4 4

5 5

6 6

7 7

88

9 910 10

Apex

Ribs

Base



An anterior view showing theborders of the heart

Right border

Superior border

Inferior border

Left border

Module 18.1: Heart wall and tissue

• Layers of heart wall1. Epicardium (visceral pericardium)• Covers surface of heart• Serous membrane made of exposed mesothelium and

underlying areolar tissue (attaching to myocardium)

– Parietal pericardium• Not a heart wall layer but is continuous serous

membrane with visceral pericardium• Lines pericardial cavity and fibrous pericardial sac


• Layers of heart wall (continued)2. Myocardium• Middle, muscular layer forming atria and ventricles• Contains cardiac muscle tissue, blood vessels, and

nerves– Concentric muscle tissue layers

» Form a figure-eight around the atria» Superficial muscle layers wrap both ventricles» Deep muscle layers form figure-eight around ventricles

Figure 18.1 2

The direction of musclebundles of the atrial andventricular musculature

Ventricularmusculature

Atrialmusculature


• Layers of heart wall (continued)3. Endocardium• Covering inner surfaces of heart, including valves• Composed of simple squamous epithelial tissue and

underlying areolar tissue– Forms endothelium continuous with blood vessel

endothelium

Figure 18.1 1

A section of the heart showing its three layers: epicardium,myocardium, and endocardium

Myocardium

Endocardium

Epicardium

Parietal Pericardium

Dense fibrous layer

Areolar tissue

Mesothelium

Mesothelium

Areolar tissue

Connective tissues

Pericardial cavity(contains serous fluid)

Muscular wall of the heartconsisting primarily ofcardiac muscle cells

Areolar tissue

Covers the inner surfaces ofthe heart

Endothelium

Covers the outer surface of the heart; also calledthe visceral pericardium

The serous membrane thatforms the outer wall of thepericardial cavity; it and adense fibrous layer form thepericardial sac surroundingthe heart


• Cardiac muscle tissue– Compared to skeletal muscle tissue

1. Small cell size2. Single, centrally located nucleus3. Branching interconnections4. Specialized intercellular connections

– Intercalated discs

Figure 18.1 3

Intercalated discs

A light micrograph showingthe histological characteristicsof cardiac muscle tissue

Cardiac muscle tissue LM x 575


• Cardiac muscle tissue (continued)– Found only in the heart– Cells are striated due to organized myofibrils– Almost totally dependent on aerobic

metabolism for ATP• Large numbers of mitochondria and myoglobin to

store O2

• Has large number of capillaries to supply nutrients and O2


• Intercalated discs– Contain: • Desmosomes• Gap junctions

– Allow ions and molecules to move directly between cells» Create direct electrical connection so an action potential

can pass directly between cells

– Stabilize relative positions of adjacent cells– Allow cells to “pull together” for maximum

efficiency– All cells to function “as one” (functional syncytium)

Figure 18.1 4 – 5

The connection of cardiac muscle cells by intercalated discs,gap junctions, and desmosomes, forming a functional syncytium

Intercalated Disc

Gap junction

Z lines boundto opposing cellmembranes

Desmosomes

Intercalateddisc

Bundles ofmyofibrils

Mitochondria

Nucleus

Intercalateddisc (sectioned)

Size of a typical cardiac muscle cell:10–20 μm in diameter and50–100 μm in lengthCardiac muscle cells, which feature organized

myofibrils, aligned sarcomeres, and numerousmitochondria

The structure of cardiac muscle cells

Module 18.1 Review

a. From superficial to deep, name the layers of the heart wall.

b. Describe how the cardiac muscle cells ‘talk’ to one another.

c. Why is it important that cardiac tissue be richly supplied with mitochondria and capillaries?

Module 18.2: Pericardial cavity

• Heart lies within pericardial cavity, a subdivision of the mediastinum

• Mediastinum also contains:– Great vessels (entering and exiting the heart)– Thymus– Esophagus– Trachea

• Because heart is closely associated with many organs, trauma can lead to fluid accumulation that can restrict heart movement (cardiac tamponade)

Figure 18.2 1 – 3

The position and orientation of the heartrelative to the major vessels and the ribs,sternum, and lungs

A diagrammatic superior view of a partial dissection of thethoracic cavity showing the physical relationships among thecomponents in the mediastinumTrachea

First rib (cut)

Right lung

Diaphragm

Left lung

Thyroid gland

Base of heart

Apex of heart

Parietalpericardium(cut)Anterior view of chest cavity

Rightlung

Leftlung

Bronchusof lung

Rightpulmonary

artery

Right pulmonaryvein

Right pleural cavity

Esophagus

Right ventricle

Right atrium

Superior vena cava

Anterior mediastinum

Left atrium

Left ventricle

Left pulmonaryvein

Left pleural cavity

Left pulmonaryartery

Pericardial sac

Pericardial cavity

Epicardium

Pulmonarytrunk

Aorticarch

Posterior mediastinum

Aorta (archsegment removed)

Two views showing the location of the heart in the chest cavity

Module 18.2: Pericardial cavity

• Pericardial cavity and fluid– Lined with parietal pericardium• Continuous with visceral pericardium (like balloon

with fist in it)– Contains 10–15 mL of pericardial fluid secreted

by membranes• Acts as lubricant when heart beats

– Swelling of pericardial surfaces can occur with infection causing friction (pericarditis)

Figure 18.2 1

The position and orientation of the heartrelative to the major vessels and the ribs,sternum, and lungs Trachea

First rib (cut)

Right lung

Diaphragm

Left lung

Thyroid gland

Base of heart

Apex of heart

Parietalpericardium(cut)Anterior view of chest cavity

Figure 18.2 2

Apex of heart

Base of heart

Inner wall (correspondsto epicardium)

Air space (correspondsto pericardial cavity)

Outer wall (correspondsto parietal pericardium)

Balloon

Wrist (correspondsto base of heart)

The positions of and relationshipbetween the heart and thepericardial cavity

The relationship between the heartand the pericardial cavity, which canbe linked to a fist pressed into thecenter of a partially inflated balloon

The location of the pericardialcavity relative to the heart

Pericardial cavitycontainingpericardial fluid

Fibrous attachmentto diaphragm

Fibrous tissue ofpericardial sac

Cut edge ofparietal pericardium

Parietal Pericardium

Cut edge of epicardium

Areolar tissueMesothelium

Module 18.2 Review

a. Define mediastinum.

b. Describe the heart’s location.

c. Why can cardiac tamponade be a life-threatening condition?

Module 18.3: Heart surface anatomy

• Heart surface anoatomy– Sulci (singular, sulcus)

• Surface grooves separating heart chambers– Often with cardiac vessels covered with fat

• Anterior interventricular sulcus– Anterior groove separating ventricles

• Posterior interventricular sulcus– Posterior groove separating ventricles

• Coronary sulcus– Separates atria from ventricles – On posterior surface, contains coronary sinus (collects blood from

myocardium and conveys to right atrium)

Module 18.3: Heart surface anatomy

• Other surface features– Auricles • Expandable extensions of atria

– Ligamentum arteriosum• Fibrous remnant of fetal connection between aorta

and pulmonary trunk

Figure 18.3 1 – 3

A photograph of an anterior view ofa heart from a preserved cadaver

Rightventricle Anterior

interventricularsulcus

Leftventricle

Coronarysulcus

Right atrium

Auricle ofright atrium

Rightatrium

Auricle ofleft atrium

Left ventricle

Auricle of left atrium

Anteriorinterventricularsulcus

Coronarysulcus

Superiorvena cava

Superiorvena cava

Aortic arch

Rightventricle

Ascending aorta

Auricle

Fat

Anterior surface

Cadaver dissection, anterior view

Ascendingaorta

Pulmonarytrunk

Pulmonary trunk

Parietalpericardium

A diagrammatic view of theanterior surface of the heart

Ligamentumarteriosum

Two views of the anterior surface of the heart

Module 18.3 Review

b. Name and describe the shallow depressions and grooves found on the heart’s external surface.

c. Which structures collect blood from the myocardium, and into which heart chamber does this blood flow?

Module 18.4: Coronary circulation

• Coronary circulation– Provides cardiac muscle cells with reliable supplies

of oxygen and nutrients– During maximum exertion, myocardial blood flow

may increase to 9× resting levels– Blood flow is continuous but not steady

• With left ventricular relaxation, aorta walls recoil (elastic rebound), which pushes blood into coronary arteries


• Coronary arteries– Right coronary artery (right atrium, portions of both ventricles

and conduction system of heart)• Marginal arteries (right ventricle surface)• Posterior interventricular artery (interventricular septum and

adjacent ventricular portions)– Left coronary artery (left ventricle, left atrium, and

interventricular septum)• Circumflex artery (from left coronary artery, follows coronary

sulcus to meet right coronary artery branches)• Anterior interventricular artery (interventricular sulcus)

Figure 18.4 1 – 2

The locations of the arterial supply to the heart

An anterior view of the coronary arteries

Right Coronary Artery

Right coronary artery in the coronary sulcus

Marginal arteries

The branches of the coronary arterieson the posterior surface of the heart

Marginalartery

Right coronary artery

Rightatrium

Rightventricle

Leftatrium

Leftventricle

Rightatrium

Rightventricle

Leftatrium

Leftventricle

Posteriorinterventricularartery

Anteriorinterventricularartery

Left coronary artery

Circumflex artery

Arterial anastomosesbetween the anteriorand posteriorinterventricular arteries

Left Coronary Artery

Aorticarch

Pulmonarytrunk

Circumflex artery

Posterior view

Anterior view


• Coronary veins– Great cardiac vein (drains area supplied by

anterior interventricular artery, empties into coronary sinus on posterior)

– Anterior cardiac veins (drains anterior surface of right ventricle, empties into right atrium)

Figure 18.4 3

Leftatrium

Leftventricle

Rightatrium

Rightventricle

Aorticarch

Anterior view

Greatcardiac vein

Anterior cardiac veins

The major collecting vessels on the anteriorsurface of the heart


• Coronary veins (continued)– Coronary sinus (expanded vein, empties into right

atrium)– Posterior cardiac vein (drains area supplied by

circumflex artery)– Small cardiac vein (drains posterior right atrium

and ventricle, empties into coronary sinus)– Middle cardiac vein (drains area supplied by

posterior interventricular artery, drains into coronary sinus)

Figure 18.4 4

Leftventricle

Rightventricle

Rightatrium

Leftatrium

Posterior view

Posteriorcardiac vein

Greatcardiac vein

Middlecardiac vein

Smallcardiac vein

Coronary sinus

The major collecting vessels onthe posterior surface of the heart

Module 18.4 Review

a. List the arteries and veins of the heart.

b. Describe what happens to blood flow during elastic rebound.

c. Identify the main vessel that drains blood from the myocardial capillaries.

Module 18.5: Internal heart anatomy

• Internal heart anatomy– Four chambers• Two atria (left and right separated by interatrial

septum)• Two ventricles (left and right separated by

interventricular septum)– Left atrium flows into left ventricle– Right atrium flows into right ventricle


• Right atrium– Receives blood from superior and inferior

venae cavae and coronary sinus– Fossa ovalis (remnant of fetal foramen ovale)– Pectinate (pectin, comb) muscles (muscular

ridges on anterior atrial and auricle walls)• Left atrium– Receives blood from pulmonary veins


• Right ventricle– Receives blood from right atrium through right

atrioventricular (AV) valve• Also known as tricuspid (tri, three)

– Has three flaps or cusps attached to tendinous connective fibers (chordae tendineae)

– Fibers connect to papillary muscles» Innervated to contract through moderator band which

keeps “slamming” of AV cusps

• Prevents backflow of blood to atrium during ventricular contraction


• Left ventricle– Receives blood from left atrium through right atrioventricular

valve• Also known as bicuspid and mitral (mitre, bishop’s hat) valve• Prevents backflow of blood to atrium during ventricular

contraction• Has paired flaps or cusps

– Trabeculae carneae (carneus, fleshy)• Muscular ridges on ventricular walls

– Aortic valve • Allows blood to exit left ventricle and enter aorta

Figure 18.5 1

The internal anatomy of the heart andthe direction of blood flow betweenthe chambers

Inferiorvena cava

Left AtriumRight Atrium

Left Ventricle

Aortic arch

Pulmonarytrunk

Superiorvena cava

Aortic valve

Ascendingaorta

Moderatorband

Interventricularseptum

Fossa ovalis

Pectinate muscles on the innersurface of the auricle

Opening of the coronary sinus

Receives blood from the superiorand inferior venae cavae and fromthe cardiac veins through thecoronary sinus

Right Ventricle

Left pulmonary veins

Receives blood fromthe pulmonary veins

Thick wall of left ventricle

Left atrioventricular (AV)valve (bicuspid valve)

Trabeculae carneae

Chordae tendineae

Right atrioventricular (AV)valve (tricuspid valve)

Papillary muscle

Pulmonary valve (pulmonarysemilunar valve)


• Ventricular comparisons– Right ventricle has relatively thin wall

• Ventricle only pushes blood to nearby pulmonary circuit• When it contracts, it squeezes against left ventricle wall forcing

blood out pulmonary trunk– Left ventricle has extremely thick wall and is round in cross

section• Ventricle must develop 4–6× as much pressure as right to push

blood around systemic circuit• When it contracts

1. Diameter of chamber decreases2. Distance between base and apex decreases

Figure 18.5 2

A sectional view of the heart showingthe thicknesses of the ventricle wallsand the shapes of the ventricularchambers

The relatively thin wallof the right ventricleresembles a pouchattached to the massivewall of the left ventricle

The left ventricle hasan extremely thickmuscular wall and isround in cross section.

Fat in anteriorinterventricular sulcus

Posteriorinterventricular sulcus

Figure 18.5 3

Leftventricle

Rightventricle

The changes in ventricleshape during ventricularcontraction

Dilated (relaxed)

Contracted

Contraction of rightventricle squeezesblood against the thickwall of the left ventricle.

Contraction of left ventricledecreases the diameter of theventricular chamber and reducesthe distance between the baseand apex

Module 18.5 Review

a. Damage to the semilunar valves on the right side of the heart would affect blood flow to which vessel?

b. What prevents the AV valves from swinging into the atria?

c. Why is the left ventricle more muscular than the right ventricle?

d. Name the four cardiac chambers.

transportation. section 1: blood cardiovascular system – includes: fluid (blood) – includes ~75...

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