Unit 4 - A & P Module - Cardiac Cycle and Regulation of Cardiac Output

Question 1

Ventricular contractility is influenced by __________.

Answer 1

calcium and epinephrine

Question 2

End diastolic volume is influenced directly or indirectly by __________.

Answer 2

heart rate, preload, afterload, sympathetic nerve activity

Question 3

Put the following events of the cardiac cycle in the correct order, starting with the ventricular filling phase:

first heart sound
P wave of ECG
ventricular pressure > atrial pressure
isovolumetric relaxatio

Answer 3

b, c, a, d

Question 4

Starling’s law of the heart can be stated as: __________.

Answer 4

if end diastolic volume increases, stroke volume will increase and if venous return decreases, end diastolic volume will decrease and stroke volume will decrease

Question 5

Which of the following would result in an increase in cardiac output?

Answer 5

Increased end diastolic volume

Question 6

The actions of norepinephrine and acetylcholine on pacemaker cells is similar in that both transmitters __________.

Answer 6

utilize G proteins and affect calcium channels

Question 7

Stroke volume can be influenced by __________.

Answer 7

preload, contractility, afterload, and sympathetic nerve activity

Question 8

The effect of parasympathetic input to the heart is to __________.

Answer 8

open additional potassium channels in pacemaker cells

Question 9

Starling’s law states that __________.

Answer 9

stroke volume increases as end-diastolic volume increases

Question 10

Regarding ventricular volumes __________.

Answer 10

the larger the end diastolic volume, the larger the stroke volume becomes and an increase in the force of ventricular contraction decreases the end systolic volume

Question 11

Which of the following will increase the force of contraction of the ventricles?

Answer 11

Increasing end diastolic volume

Question 12

The pulmonary semilunar valve opens in response to __________.

Answer 12

right ventricle pressure > pulmonary artery pressure

Question 13

Cardiac output is increased by __________.

Answer 13

increasing venous return and increasing ventricular filling time

Question 14

Which of the following may increase heart rate?

Answer 14

Norepinephrine and epinephrine

Question 15

Abnormalities within the SA node can cause which of the following symptoms?

Answer 15

Bradycardia or tachycardia

Question 16

Which of the following would result in an increase in cardiac output?

Answer 16

Increased end diastolic volume

Question 17

Sympathetic activity increases ventricular contractility by __________.

Answer 17

increasing the rate of myosin ATPase activity and increasing the flow of calcium into the cytosol

Question 18

Which of the following are the same for the left and right ventricles?

Answer 18

Cardiac output, heart rate, and stroke volume

Question 19

During the plateau phase of the action potential in cardiac contractile cells __________.

Answer 19

calcium channels are open, the membrane potential remains depolarized, inward rectifier potassium channels are closed, sodium channels are inactivated

Question 20

The second heart sound occurs during which aspect of the ECG?

Answer 20

T wave

Question 21

When you begin to exercise, the working tissue will need an increased delivery of blood in order to obtain the oxygen and nutrients necessary for the maintenance of the increased metabolism. Which of the following will occur in order to help enhance the blood flow to the working tissue?

Answer 21

Increased heart rate and stroke volume

Question 22

During isovolumetric contraction __________.

Answer 22

pressure in the ventricles is increasing

Question 23

During exercise, sympathetic input to the heart is increased. Stroke volume is often maintained, or even increased, even though heart rate is also increasing. How is this possible?

Answer 23

Sympathetic input increases ventricular contractility, thereby increasing stroke volume, and sympathetic input decreases conduction time within the heart, decreasing the delay between atrial and ventricular contractions, and
Sympathetic input increases the speed of ventricular contraction.

Question 24

Give the mechanistic explanation as to why tetanus does NOT occur in myocardial contractile cells?

Answer 24

Calcium entry depolarizes the cell and lengthens the refractory period, which prevents the summation of the tension developed from repeated action potentials.

Question 25

All of the following increase stroke volume __________.

Answer 25

constriction of veins due to norepinephrine binding to alpha receptors, skeletal muscle activity during exercise, and an increase in contractile fiber length

Question 26

During isovolumetric relaxation __________.

Answer 26

the blood has been ejected from the ventricle, the ventricle is expanding and pressure within the ventricle is dropping, atrioventricular valves do not open, the semilunar valves have been closed, which results in no gain of blood in the ventricle, the pressure in the ventricle is less than the pressure in the aorta, the second heart sound is heard at the very beginning of isovolumetric relaxation, no contraction is happening during isovolumetric relaxation