Chapter 18

Why is the left ventricle more muscular than the right ventricle? (Module 18.6A)

The left ventricle must generate enough force to propel blood through the systemic circuit, whereas the right ventricle must generate only enough force to propel blood the short distance from the heart to the lungs in the pulmonary circuit.

List the phases of the cardiac cycle. (Module 18.10A)

atrial systole, atrial diastole, ventricular systole, ventricular diastole

Which valve(s) close(s) during ventricular contraction?

both AV valves

The heart is innervated by ________ nerves.

both parasympathetic and sympathetic

The first heart sound ("lubb") is associated with

closing of the mitral valve

The function of the atrium is to

collect blood and pump blood to the ventricle.

The P wave of the electrocardiogram is a signal from

depolarization of the atria.

As the heart rate slows, ________ get(s) longer.

diastole

The ________ is the volume of blood in a ventricle at the beginning of systole.

end-diastolic volume

The ________ separate(s) the two atria.

interatrial septum

The circumflex branch and the anterior interventricular artery are branches of the

left coronary artery.

The cavity that contains only the heart is the

pericardial cavity.

Damage to the semilunar valve on the right side of the heart would affect blood flow to which vessel? (Module 18.6B)

pulmonary trunk

As blood leaves the right ventricle, it passes through the ________ and then into the pulmonary trunk.

pulmonary valve

Blood leaves the right ventricle by passing through the

pulmonary valve.

The right ventricle pumps blood to the

right and left lungs.

Identify the correct sequence for blood flow through the heart.

right ventricle, through pulmonary valve, pulmonary trunk, pulmonary arteries

If the connection between the SA node and AV node becomes blocked,

the ventricles will beat more slowly.

The cavity that contains the lungs, the heart, great vessels, thymus, esophagus, and trachea is called the

thoracic cavity.

Muscular ridges on the inner surface of the ventricles are called

trabeculae carneae.

Define cardiac regurgitation. (Module 18.7A)

Cardiac regurgitation is the backflow of blood into the atria when the ventricles contract.

Why does tetany not occur in cardiac muscle? (Module 18.11A)

Tetany does not occur because cardiac muscle has a long refractory period that continues until relaxation is well under way so summation cannot occur, and thus tetany cannot occur.

The ________ separate(s) the two ventricles.

interventricular septum

Compare the base of the heart with the apex. (Module 18.1B)

The base of the heart is the superior portion where the largest veins and arteries are attached. The apex of the heart is located on the inferior aspect of the heart.

Name the four chambers of the heart. (Module 18.1C)

left atrium, left ventricle, right atrium, right ventricle

Blood returning to the heart from the pulmonary circuit first enters the

left atrium.

Blood is supplied to the left atrium by the

left coronary artery

The ________ has a greater workload than the ________.

left ventricle; right ventricle

The coronary sulcus is a groove that

marks the border between the atria and ventricles.

Cardiac muscle cells are __________.

mechanically, chemically, and electrically connected to one another.

Heart rate is controlled by neurons of the cardiovascular center located in the

medulla oblongata.

The interventricular sulci and coronary sulcus contain all of the following except

nerves.

Describe the location and position of the heart. (Module 18.1A)

The heart is located near the anterior chest wall, directly behind the sternum.

Describe the heart's location in the body. (Module 18.2B)

The heart is surrounded by the pericardium in the anterior mediastinum, deep to the sternum and superior to the diaphragm.

If the cells of the SA node failed to function, how would the heart rate be affected? (Module 18.12B)

The heart would beat slower because the AV node would be the pacemaker.

Define mediastinum. (Module 18.2A)

The mediastinum is the region between the two pleural cavities that contains the heart, along with the great vessels, thymus, esophagus, and trachea.

Which of these would cause stroke volume to increase?

both when venous return is increased and when diastolic blood pressure is decreased

The term used to describe fluid collecting in the pericardial cavity that restricts the movement of the heart is known as

cardiac tamponade.

The first blood vessels to branch from the aorta are the ________ arteries.

coronary

The ________ is the amount of blood in a ventricle after it has contracted and before it begins to refill.

end-systolic volume Submit

Averaged over a few heartbeats, venous return is ________ cardiac output.

equal to

The heart beats approximately ________ times each day.

100,000

There are ________ pulmonary veins.

4

The heart pumps approximately ________ milliliters of blood each minute.

6,000

Compare arteriosclerosis with atherosclerosis. (Module 18.8A)

Arteriosclerosis is any thickening and toughening of arterial walls; atherosclerosis is a type of arteriosclerosis characterized by changes in the endothelial lining and the formation of fatty deposits (plaque) in the tunica media.

What do semilunar valves prevent? (Module 18.7C)

Semilunar valves prevent backflow of blood into the ventricles.

Intercalated discs serve to transfer all of the following from cell to cell except

Z-lines.

What factor would decrease stroke volume?

an increase in afterload

What superficial landmark identifies the boundary between the left and right ventricles?

anterior interventricular sulcus

Which of the following does not directly affect blood flow through the body?

kidney disease

The left border of the heart is formed by the

left atrium and left ventricle.

The amount of blood returning to the heart is the

venous return

The wall(s) of the ________ rest(s) on the diaphragm.

right ventricle

The volume of blood ejected from each ventricle during a contraction is called the

stroke volume.

A faster-than-normal heart rate is called

tachycardia

The normal pacemaker of the heart is located in

the sinoatrial node.

The relaxation phase of the lower chambers of the heart is called

ventricular diastole.

The T wave on an ECG tracing represents

ventricular repolarization

During which phase of the cardiac cycle is the blood pumped to the body?

ventricular systole

During ventricular systole, the

AV valves are closed

Define electrocardiogram. (Module 18.13A)

An electrocardiogram is a recording of the electrical activity of the heart.

Define autorhythmicity. (Module 18.12A)

Autorhythmicity is the ability of the heart to contract without neural or hormonal stimulation.

Compare bradycardia with tachycardia. (Module 18.14A)

Bradycardia is a heart rate below 60 beats per minute and tachycardia is a heart rate above 100 beats per minute.

What is coronary ischemia? (Module 18.8B)

Coronary ischemia is a condition in which the blood supply of the coronary arteries is reduced.

The ________ deliver(s) blood to the myocardium.

both right coronary artery and left coronary artery

Define heart failure. (Module 18.16A)

Heart failure is a condition where the heart can no longer meet the oxygen and nutrient demands of peripheral tissues

Which ECG event demonstrates the depolarization of the atria?

P wave

________ is to contraction as ________ is to relaxation

Systole; diastole

Why is ventricular fibrillation fatal? (Module 18.13C)

Ventricular fibrillation is fatal because the ventricles quiver and do not pump blood to the systemic circulation.

The left ventricle pumps blood to the

aorta

What is the first phase of the cardiac cycle?

atrial systole

The contraction phase of the upper chambers of the heart is called

atrial systole.

The earlike extension of the atrium is the

auricle

The bicuspid, or mitral, valve is located

between left atrium and left ventricle

When the semilunar valves close, the AV valves then

open

The right atrium receives blood from all of the following except the

pulmonary veins.

List the three stages of an action potential in a cardiac muscle cell. (Module 18.11B)

rapid depolarization, plateau, and repolarization

During the T wave of the electrocardiogram, the ventricles are electrically ________ and functionally ________.

repolarizing; relaxing

Coronary veins empty into the

right atrium

The anterior view of the heart is dominated by which chambers? (Module 18.4A)

right atrium and right ventricle