Question 1

Match the valve abnormalities, labelled a. and b., with the descriptions. (Options may be used more than once or not at all.)
-produces a "whistling" murmur

Accepted Answer

Valvular stenosis is characterized by the narrowing of the valve opening, which restricts blood flow and can produce a "whistling" or high-pitched murmur as blood forces its way through the narrowed valve.

Question 2

Match the factor involved in the initiation and spread of cardiac excitation, labelled a. through d. with the description. (Options may be used more than once or not at all.)
-the normal pacemaker of the heart

Accepted Answer

The SA node, or sinoatrial node, is recognized as the normal pacemaker of the heart because it initiates the electrical impulses that set the pace for cardiac activity.

Question 3

Match the effects with sympathetic or parasympathetic stimulation (or neither) of the heart. (Options may be used more than once or not at all.)
-decreases the contractility of the ventricular muscle

Accepted Answer

The parasympathetic nervous system primarily affects the heart rate and has little to no effect on ventricular contractility. The sympathetic nervous system increases contractility, so a decrease is not caused by either system.

Question 4

Match the ions, labelled a. through c., with the events being described. (Options may be used more than once or not at all.)
-The rapid falling phase of the cardiac action potential is brought about primarily by the outward diffusion of _____.

Accepted Answer

The rapid falling phase of the cardiac action potential is primarily caused by the outward diffusion of potassium ions (K⁺).

Question 5

Match the factor involved in the initiation and spread of cardiac excitation, labelled a. through d. with the description. (Options may be used more than once or not at all.)
-delays conduction of the impulse

Accepted Answer

The AV node is responsible for delaying the conduction of the impulse, allowing the atria time to contract and fill the ventricles with blood before the ventricles contract.

Question 6

Match the effects with sympathetic or parasympathetic stimulation (or neither) of the heart. (Options may be used more than once or not at all.)
-increases the AV nodal delay

Accepted Answer

The parasympathetic nervous system, through the action of the vagus nerve, can increase the AV nodal delay, effectively slowing the heart rate by increasing the time it takes for electrical impulses to pass from the atria to the ventricles.

Question 7

Match the factor involved in the initiation and spread of cardiac excitation, labelled a. through d. with the description. (Options may be used more than once or not at all.)
-the only point of electrical contact between the atria and ventricles

Accepted Answer

The AV node is the only point of electrical contact between the atria and ventricles, as it is the only structure that physically connects the two chambers. The SA node initiates the electrical activity, the bundle of His and Purkinje system rapidly transmits the electrical impulse to the ventricles, and gap junctions allow for the spread of electrical activity between adjacent cardiac cells.

Question 8

Match the effects with sympathetic or parasympathetic stimulation (or neither) of the heart. (Options may be used more than once or not at all.)
-decreases the contractility of the atrial muscle

Accepted Answer

This effect is caused by parasympathetic stimulation, which slows down heart rate and decreases the strength of atrial contractions.

Question 9

Match the valve abnormalities, labelled a. and b., with the descriptions. (Options may be used more than once or not at all.)
-valve does not close completely

Accepted Answer

Valvular insufficiency, also known as regurgitation, occurs when a valve does not close completely, allowing blood to flow backward.

Question 10

Match the ions, labelled a. through c., with the events being described. (Options may be used more than once or not at all.)
-Parasympathetic stimulation increases the permeability of the SA node to _____, whereas sympathetic stimulation decreases the permeability to this same ion.

Accepted Answer

Parasympathetic stimulation increases the permeability of the SA node to potassium ions (K⁺), which causes the cell to become more negative and slows down the rate of depolarization.

Answer: B
 Sympathetic stimulation decreases the permeability of the SA node to sodium ions (Na⁺), which slows down the rate of depolarization and increases the threshold potential, making it more difficult to trigger an action potential.

Answer: C
 Calcium ions (Ca²⁺) have an important role in the contracting of muscle cells, but they are not directly involved in the depolarization of the SA node. Therefore, they are not the best choice for this question.

Question 11

Match the factor involved in the initiation and spread of cardiac excitation, labelled a. through d. with the description. (Options may be used more than once or not at all.)
-allows the impulse to spread from cell to cell

Accepted Answer

Gap junctions allow the impulse to spread from cell to cell by providing direct electrical connections between cardiac muscle cells.

Question 12

Match the factor involved in the initiation and spread of cardiac excitation, labelled a. through d. with the description. (Options may be used more than once or not at all.)
-has the fastest rate of pacemaker activity

Accepted Answer

The SA node has the fastest rate of pacemaker activity, setting the pace for the heart rate because it generates impulses more frequently than other parts of the heart's conduction system.

Question 13

Match the ions, labelled a. through c., with the events being described. (Options may be used more than once or not at all.)
-Explosive increase in membrane permeability to _____ brings about the rapidly rising phase of the action potential in contractile cardiac cells.

Accepted Answer

The explosive increase in membrane permeability to Na+ brings about the rapidly rising phase of the action potential in contractile cardiac cells.

Question 14

Match the factor involved in the initiation and spread of cardiac excitation, labelled a. through d. with the description. (Options may be used more than once or not at all.)
-rapidly conducts the impulse down the ventricular septum and throughout much of the ventricular musculature

Accepted Answer

The bundle of His and Purkinje system rapidly conducts the impulse down the ventricular septum and throughout much of the ventricular musculature.

Answer: D
 Gap junctions play a critical role in the spread of cardiac excitation by allowing electrical impulses to rapidly spread from cell to cell.

Answer: A 
 The SA node is the natural pacemaker of the heart and initiates the electrical activity that leads to a heartbeat.

Answer: B 
 The AV node serves as a gatekeeper for the electrical impulse, delaying it slightly to allow for proper contraction of the atria before transmitting it to the ventricles.

Question 15

Match the valve abnormalities, labelled a. and b., with the descriptions. (Options may be used more than once or not at all.)
-produces a "gurgling" murmur

Accepted Answer

Valvular insufficiency, also known as regurgitation, can produce a "gurgling" murmur due to the backflow of blood through the incompetent valve.

Question 16

Match the effects with sympathetic or parasympathetic stimulation (or neither) of the heart. (Options may be used more than once or not at all.)
-decreases the rate of depolarization to threshold of the SA node

Accepted Answer

This effect is caused by parasympathetic stimulation, which releases acetylcholine and slows down the depolarization of the SA node.

Answer: A 
 This effect is caused by sympathetic stimulation, which releases norepinephrine and increases the rate of depolarization to threshold of the SA node.

Answer: C 
 This effect is not brought about by either sympathetic or parasympathetic stimulation.

Question 17

Match the ions, labelled a. through c., with the events being described. (Options may be used more than once or not at all.)
-Inactivation of _____ channels brings about the slow drift of membrane potential to threshold in the cardiac autorhythmic cells.

Accepted Answer

The answer of Match the ions, labelled a. through c.,...

Question 18

Match the ions, labelled a. through c., with the events being described. (Options may be used more than once or not at all.)
-Changes in cytosolic _____ concentration bring about changes in the strength of cardiac contraction.

Accepted Answer

Calcium ions play a critical role in the contraction of cardiac muscle cells. An increase in cytosolic calcium concentration leads to an increase in the strength of cardiac contraction. Potassium and sodium ions are involved in generating action potentials, but do not directly affect the strength of contraction.

Question 19

Match the effects with sympathetic or parasympathetic stimulation (or neither) of the heart. (Options may be used more than once or not at all.)
-increases the contractility of the atrial and ventricular muscle

Accepted Answer

Sympathetic stimulation increases the contractility of the atrial and ventricular muscle.

Answer: B
 Parasympathetic stimulation does not increase the contractility of the heart.

Answer: C
 This effect is not brought about by either sympathetic or parasympathetic stimulation.

Question 20

Match the ions, labelled a. through c., with the events being described. (Options may be used more than once or not at all.)
-Slow inward diffusion of _____ is largely responsible for the plateau portion of the cardiac action potential.

Accepted Answer

The slow inward diffusion of Ca²⁺ is largely responsible for the plateau portion of the cardiac action potential.

Answer: A
 K⁺ plays a role in repolarization of the cardiac action potential, not the plateau phase.

Answer: B
 Na⁺ plays a role in depolarization during the rapid upswing of the cardiac action potential, not the plateau phase.

Quiz 8: Cardiac Physiology

Match the valve abnormalities, labelled a. and b., with the descriptions. (Options may be used more than once or not at all.) -produces a "whistling" murmur

Match the factor involved in the initiation and spread of cardiac excitation, labelled a. through d. with the description. (Options may be used more than once or not at all.) -the normal pacemaker of the heart

Match the effects with sympathetic or parasympathetic stimulation (or neither) of the heart. (Options may be used more than once or not at all.) -decreases the contractility of the ventricular muscle

Match the ions, labelled a. through c., with the events being described. (Options may be used more than once or not at all.) -The rapid falling phase of the cardiac action potential is brought about primarily by the outward diffusion of _____.

Match the factor involved in the initiation and spread of cardiac excitation, labelled a. through d. with the description. (Options may be used more than once or not at all.) -delays conduction of the impulse

Match the effects with sympathetic or parasympathetic stimulation (or neither) of the heart. (Options may be used more than once or not at all.) -increases the AV nodal delay

Match the factor involved in the initiation and spread of cardiac excitation, labelled a. through d. with the description. (Options may be used more than once or not at all.) -the only point of electrical contact between the atria and ventricles

Match the effects with sympathetic or parasympathetic stimulation (or neither) of the heart. (Options may be used more than once or not at all.) -decreases the contractility of the atrial muscle

Match the valve abnormalities, labelled a. and b., with the descriptions. (Options may be used more than once or not at all.) -valve does not close completely

Match the ions, labelled a. through c., with the events being described. (Options may be used more than once or not at all.) -Parasympathetic stimulation increases the permeability of the SA node to _____, whereas sympathetic stimulation decreases the permeability to this same ion.

Match the factor involved in the initiation and spread of cardiac excitation, labelled a. through d. with the description. (Options may be used more than once or not at all.) -allows the impulse to spread from cell to cell

Match the factor involved in the initiation and spread of cardiac excitation, labelled a. through d. with the description. (Options may be used more than once or not at all.) -has the fastest rate of pacemaker activity

Match the ions, labelled a. through c., with the events being described. (Options may be used more than once or not at all.) -Explosive increase in membrane permeability to _____ brings about the rapidly rising phase of the action potential in contractile cardiac cells.

Match the factor involved in the initiation and spread of cardiac excitation, labelled a. through d. with the description. (Options may be used more than once or not at all.) -rapidly conducts the impulse down the ventricular septum and throughout much of the ventricular musculature

Match the valve abnormalities, labelled a. and b., with the descriptions. (Options may be used more than once or not at all.) -produces a "gurgling" murmur

Match the effects with sympathetic or parasympathetic stimulation (or neither) of the heart. (Options may be used more than once or not at all.) -decreases the rate of depolarization to threshold of the SA node

Match the ions, labelled a. through c., with the events being described. (Options may be used more than once or not at all.) -Inactivation of _____ channels brings about the slow drift of membrane potential to threshold in the cardiac autorhythmic cells.

Match the ions, labelled a. through c., with the events being described. (Options may be used more than once or not at all.) -Changes in cytosolic _____ concentration bring about changes in the strength of cardiac contraction.

Match the effects with sympathetic or parasympathetic stimulation (or neither) of the heart. (Options may be used more than once or not at all.) -increases the contractility of the atrial and ventricular muscle

Match the ions, labelled a. through c., with the events being described. (Options may be used more than once or not at all.) -Slow inward diffusion of _____ is largely responsible for the plateau portion of the cardiac action potential.