Question 1

During isovolumetric contraction, which chamber has the greatest pressure?

Accepted Answer

During isovolumetric contraction, all valves are closed and the ventricles are contracting to increase pressure. The left ventricle has the greatest pressure because it needs to overcome the high pressure in the systemic circulation during its ejection phase.

Question 2

Which of the following describes second- degree heart block?

Accepted Answer

In second-degree heart block, some atrial impulses fail to conduct to the ventricles, resulting in some atrial contractions not being followed by ventricular contractions.

Question 3

During repolarization (phase 3)of a contractile cell action potential,

Accepted Answer

During repolarization, the voltage-gated potassium channels open, allowing potassium ions to move out of the cell. This increase in potassium permeability leads to the reestablishment of the negative membrane potential, returning the cell to its resting state. Sodium and calcium permeability both decrease during this phase as the voltage-gated ion channels responsible for allowing them into the cell close.

Question 4

An increase in venous return would result in a(n)

Accepted Answer

An increase in venous return leads to more blood entering the heart during diastole, which increases the end-diastolic volume (EDV).

Question 5

The preload is approximately the same as the pressure.

Accepted Answer

Preload is the initial stretching of the cardiac myocytes prior to contraction, which is best approximated by the end-diastolic pressure.

Question 6

What structure separates the thoracic cavity from the abdominal cavity?

Accepted Answer

The diaphragm is a muscle that separates the thoracic cavity from the abdominal cavity.

Question 7

In what phase is the cardiac cycle when the AV valves are open and semilunar valves are closed?

Accepted Answer

During ventricular filling, the AV valves are open to allow blood flow from the atria to the ventricles, while the semilunar valves are closed to prevent backflow of blood into the ventricles.

Question 8

Which component of an ECG represents ventricular depolarization?

Accepted Answer

The QRS complex represents ventricular depolarization, which is the contraction of the ventricles. The P wave represents atrial depolarization, the T wave represents ventricular repolarization, and the P-R and Q-T intervals are measurements of time between specific points on the ECG.

Question 9

Which of the following best describes the effect of sympathetic activity on ventricular contractile cells?

Accepted Answer

Sympathetic activity increases the rates of contraction and relaxation as well as the force of contraction in ventricular contractile cells due to the release of norepinephrine, which enhances calcium influx and uptake.

Question 10

If both the SA node and the AV node fail, what would be the expected outcome of impulse rate within the heart?

Accepted Answer

The Purkinje fibers can act as a secondary pacemaker, generating a slower heart rate of 30-40 beats per minute if both the SA and AV nodes fail.

Question 11

The circulatory system consists of two divisions and is supplied with blood by different sides of the heart. The right heart supplies blood to the _ circuit, whereas the left heart supplies blood to the circuit.

Accepted Answer

The right heart pumps deoxygenated blood to the pulmonary circuit (lungs), and the left heart pumps oxygenated blood to the systemic circuit (rest of the body).

Question 12

Which of the following is the correct conduction pathway through the heart?

Accepted Answer

The correct conduction pathway through the heart is SA node, AV node, bundle of His, bundle branches, and Purkinje fibers. This sequence ensures the proper timing of heart muscle contraction.

Question 13

Which of the following statements best describes the function of the chordae tendineae?

Accepted Answer

The chordae tendineae prevent the atrioventricular (AV) valves from prolapsing into the atria during ventricular contraction by anchoring the valve cusps to the papillary muscles.

Question 14

Which statement best describes why atrial depolarization is usually not detected on a normal ECG?

Accepted Answer

Atrial depolarization is usually not detected on a normal ECG because it occurs at the same time as the QRS complex, which represents ventricular depolarization and is much larger, thus overshadowing the atrial signal.

Question 15

Keeping blood on the left side of the heart from mixing with the blood on the right side is a function of what structure(s)?

Accepted Answer

The septum is the structure that separates the left and right sides of the heart, preventing the mixing of oxygenated and deoxygenated blood.

Question 16

What chamber empties into the aorta?

Accepted Answer

The left ventricle empties into the aorta, which is the largest artery in the body and carries oxygenated blood away from the heart to the rest of the body.

Question 17

Closure of the atrioventricular valve occurs when

Accepted Answer

The atrioventricular valve closes when the pressure inside the ventricle becomes greater than the pressure inside the atrium, preventing backflow of blood into the atrium.

Question 18

What phase of the cardiac cycle is the heart in when all four valves of the heart are closed and ventricular pressure is building, but is not yet great enough to open a valve?

Accepted Answer

During isovolumetric contraction, all heart valves are closed, and the ventricles contract, increasing pressure without changing volume until the pressure is high enough to open the semilunar valves.

Question 19

Which of the following factors determines preload?

Accepted Answer

Preload is primarily determined by venous return and heart rate, as it refers to the initial stretching of the cardiac myocytes prior to contraction, which is influenced by the volume of blood returning to the heart.

Question 20

Which of the following describes the effect of end- diastolic volume on stroke volume?

Accepted Answer

An increase in end-diastolic volume stretches the ventricular muscle cells closer to their optimal length, enhancing the force of contraction and increasing stroke volume, according to the Frank-Starling law of the heart.

Quiz 13: The Cardiovascular System: Cardiac Function