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
