Chapter 5

The Cardiovascular

System

Key Concepts

• artery• arteriovenus

anastomoses (AV shunts)

• arterioles• atrium• atrioventricular

(AV) node• autorhythmicity

• blood flow• blood pressur

e• cardiac contr

actility• cardiac cycle• cardiac outpu

t (CO)• cardiac reser

ve

• diastole• dynamic exercise• end diastolic volu

me (EDV)• end systolic volu

me (ESV)• ephatic

conduction • exercise intensity

• Fick method• Frank-Starling law of t

he heart• heart murmur• indicator dilution

method• maximum heart rate

(HRmax)• non-pathologic

cardiac hypertrophy

• pathologic cardiac hypertrophy

• pressure gradient• pulmonary veins• reserve of heart rate• resistance vessels• resting heart rate• sinoatrial (SA) node• static exercise

• stroke volume (SV)

• stroke volume reserve

• systole• vagus nerve• veins• ventricles• venules

Review Questions

On the following diagram of the heart, what do A through K refer to?

A.B.C.D.E.F.G.H.I.J.K.

Atria (Left/Right)

Superior vena cava

Inferior vena cava

Pulmonary veins

Pulmonary artery

AortaVentricle (Left/Right)

Right (AV) valveLeft (AV) valveAortic valve

C

A A

B B

D

E

F

G

H

I

J Pulmonary valve

K

Describe the heart as two pumps.

• The right heart pumps blood to the lungs, where the blood is oxygenated.

• The left heart pumps the oxygenated blood to the systemic circulation.

Describe the different kinds of blood vessels.• Arteries

– carry blood away from the heart and toward the tissues• Veins

– carry blood from the tissues back to the heart• Pulmonary veins

– carry oxygenated blood from the lungs to the left heart to be pumped out into the systemic circulation

• Arterioles– are muscular vessels that keep the pressure low in the

capillaries• Capillaries

– are thin-walled vessels through which gases, nutrients, and waste products are exchanged

• Venules – are very small vessels that connect capillaries to veins

In the following diagram of the conducting system of the heart, what are A through G?

A.B.C.D.E.F.G.

Sinoatrial (SA) node

Atrioventricular (AV) nodeBundle of His

Bundle branches (Left/Right)Purkinje system

Superior vena cavaInternodal pathways

A

B

CD

E

F

G

What occurs during diastole?

The ventricles fill with blood

What occurs during systole?

The ventricular muscle contracts to force blood out of the chambers of the ventricles.

What is the purpose of heart valves?

Valves create unidirectional blood flow. After

blood passes through them, they close,preventing the backflow of blood.

What is the formula for determining cardiac output?

CO=HR x SV, where HR is heart rate and SV is stroke volume.

What is the Fick method of estimating CO?

Determining the rate at which oxygen is added

to the blood as it flows through the lungs. This

results in an estimation of pulmonary blood

flow, which is equal to CO.

What is the indicator dilution method of determining the CO?

Involves injecting dye into a large vein or the

right atrium. The concentration of the dye as it

passes through an artery is recorded and the

CO is estimated from this information.

What is the role of vagus fibers on the heart rate?

They have an inhibitory influence on the SA

node, so they decrease the heart rate.

What is the role of sympathetic fibers on the heart rate?

They have a stimulatory influence on the SA

node, so they increase the heart rate.

What are the 9 factors that affect heart rate? Why?1. Age2. Gender

3. Size

4. Posture

5. Ingestion of food

6. Smoking7. Emotion8. Body temperature

9. Heat and humidity

heart rate decreases with ageresting heart rate of women is faster than menin general, heart rate is inversely related to sizethe change from lying down to standing up increases heart rateresting heart rate is higher following a mealsignificantly increases heart rateincreases heart rateheart rate increases as body temp. increasesheart rate increases in hot weather

Name four factors that affect stroke volume. Why?• Gravity

• Muscular activity

• Size of the heart

• Nervous influences

Can cause blood to pool in the lower extremities, decreasing venous return.

Contracting muscles put pressure on veins, causing blood to be shunted toward the heart.

Larger hearts contract more forcefully than smaller ones.

Regular exercise trains the nervous system to respond more efficiently to the demands of the exercise.

Name three reasons why heart rate is more important than stroke volume in aerobic exercise.

1. Stroke volume levels out at approximately eight times the resting level

2. Heart rate is proportional to the work load imposed

3. Heart rate is proportional to the oxygen consumed

What are the stages of typical heart rate response to exercise?

1. At the beginning of exercise, the heart rate rises rapidly.

• For light or moderate exercise, a plateau is reached within the first minute.

• For vigorous exercise, the heart rate increases until exhaustion.

2. At the end of exercise, the heart rate rapidly declines within the first two or three minutes.

3. After the initial rapid decline, the rate decreases more slowly.

What differences in exercise affect heart rate?

1. Static vs. dynamic exercise2. Intensity of the exercise3. Duration of the exercise

How does heart rate respond to static and dynamic exercise?

Only a slight increase in heart rate occurs

during static exercise, whereas largeincreases in heart rate can occur

duringdynamic exercise.

Name three ways training affects the heart.

• Decreases resting heart rate and heart rate during exercise

• Increases stroke volume• Increases cardiac reserve capacity

How does aerobic exercise affect blood pressure?

Aerobic exercise elevates systolicpressure but has little effect on

diastolicpressure.

How does isometric exercise affect blood pressure?

The intrathoracic pressure dramatically

increases, decreasing venous return to

the right atrium and putting a greater

load on the heart.

Cardiac patients and older adults should avoid aerobic exercise. True or False?

False. Isometric exercise puts a much

heavier load on the heart and should be

avoided for these people.

Useful Websites

Cardiovascular systemwww.innerbody.com/image/cardov.html

American Heart Associationwww.americanheart.org

The Heart.Org Cardiology Onlinewww.theheart.org/index.cfm

AACVPR—American Association of Cardiovascular and Pulmonary Rehabilitationwww.aacvpr.org

Anatomy and Physiology of the Cardiovascular System

www.mercksharpdohme.com/disease/heart/coronary_health/anatomy/home.html

Selected Images

Figure 5.1 Basic anatomy of the heart.

Figure 5.2 The conducting system of the heart. The impulse is initiated at the SA node and travels to the AV node, bundle of His, bundle branches, and Purkinje fibers.

Figure 5.4 The one-way valves of the veins. Contraction of the surrounding skeletal muscle aids in the movement of blood toward the heart, and the valves prevent blood from moving away from the heart.

Figure 5.6 The microcirculation.