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Why is the delay of action potential conduction at the AV node crucial to normal heart function?

It allows the atria to contract before the ventricles depolarize and contract.

It prevents heart murmurs (valve dysfunction).

It prevents the atria from contracting.

It decreases the pressure generated in the right side of the heart.

Which type of circulatory shock results from extreme vasodilation due to the presence of bacterial toxins causing inadequate circulation of blood throughout the body?

anaphylactic shock

cardiogenic shock

hypovolemic shock

neurogenic shock

septic shock

Which electrical event directly causes mechanical events that decrease ventricular pressure?

T wave

QRS complex

P wave

Which one of the following would cause a decrease in cardiac output?

Increased afterload on the heart.

Increased sympathetic nervous system activation.

Increased preload of cardiac muscle cells due to increased venous return.

Increased contractility of the cardiac muscle.

Which event causes the AV valves to close?

when ventricular pressure becomes greater than atrial pressure

when atrial pressure becomes greater than ventricular pressure

when ventricular pressure becomes greater than aortic pressure

when aortic pressure becomes greater than ventricular pressure

when the semilunar valves open

If venous return to the heart increases, what effect does this directly have on end-diastolic volume (EDV) and preload?

Increased venous return increases both EDV and preload of the heart.

Increased venous return increases EDV but decreases the preload of the heart.

Increased venous return decreases both EDV and preload of the heart.

Increased venous return decreases EDV but increases the preload of the heart.

Which one of the following statements is FALSE about congestive heart failure (CHF)?

Coronary atherosclerosis is one cause of CHF.

Stroke volume is higher than normal.

During CHF, cardiac output is low and blood circulation does not meet tissue needs.

Chronic/persistent hypertension is one cause of CHF.

In contractile cardiac muscle cells, called cardiac myocytes, the plateau phase of the action potential is due to:

calcium movement into the cardiac myocytes

sodium movement into the cardiac myocytes

sodium movement out of the cardiac myocytes

potassium movement out of the cardiac myocytes

potassium movement into the cardiac myocytes

calcium movement out of the cardiac myocytes

Which one of the following events occurs at the same time that the atria of the heart are contracting and pushing blood into the ventricles?

The ventricles are in diastole.

The semilunar valves are open.

Atrial pressure is less than ventricular pressure.

The AV valves are closed.