Question 1

Which of the following best describes the effect of parasympathetic stimulation on the SA node of the heart?

Accepted Answer

It hyperpolarizes the membrane potential by increasing K\+ efflux, slowing heart rate.

Question 2

During a sudden change from lying to standing, a person experiences a drop in blood pressure. Which immediate autonomic response helps restore blood pressure?

Accepted Answer

Activation of the baroreceptor reflex, increasing sympathetic outflow to raise cardiac output and total peripheral resistance.

Question 3

Which equation correctly represents cardiac output (CO)?

Accepted Answer

$$CO = HR 	imes SV$$

Question 4

A patient loses a significant amount of blood due to hemorrhage. Which of the following is a short-term compensatory mechanism initiated by the autonomic nervous system?

Accepted Answer

Activation of the baroreceptor reflex to increase heart rate and vasoconstriction.

Question 5

Which neurotransmitter is primarily responsible for increasing heart rate during sympathetic stimulation?

Accepted Answer

Norepinephrine

Question 6

How does the sympathetic nervous system affect arteriolar resistance and blood flow distribution during exercise?

Accepted Answer

It increases norepinephrine release, causing vasoconstriction in non-active tissues and vasodilation in active muscles.

Question 7

Which of the following best explains why mean arterial pressure (MAP) only rises slightly during strenuous exercise?

Accepted Answer

Cardiac output increases, but metabolic vasodilation in active muscles decreases total peripheral resistance.

Question 8

Which formula correctly relates mean arterial pressure (MAP), cardiac output (CO), and total peripheral resistance (TPR)?

Accepted Answer

$$MAP = CO 	imes TPR$$

Question 9

A patient with autonomic dysfunction is unable to increase heart rate or vasoconstrict in response to standing. What is the most likely consequence?

Accepted Answer

Orthostatic hypotension due to inadequate compensatory responses.

Question 10

Which of the following mechanisms increases stroke volume during exercise?

Accepted Answer

Increased sympathetic stimulation and enhanced venous return via the muscle and respiratory pumps.

Question 11

Which hormone is released during the long-term response to hypotension and acts to increase blood pressure by promoting fluid retention and vasoconstriction?

Accepted Answer

Vasopressin (antidiuretic hormone)

Question 12

Which of the following is a direct effect of norepinephrine on vascular smooth muscle?

Accepted Answer

Vasoconstriction of arterioles, increasing total peripheral resistance.

Question 13

During the fight-or-flight response, which branch of the autonomic nervous system predominates and what is its primary effect on the heart?

Accepted Answer

Sympathetic; increases heart rate and contractility.

Question 14

Which of the following best describes the baroreceptor reflex?

Accepted Answer

It is a rapid neural response that adjusts sympathetic and parasympathetic activity to maintain arterial blood pressure.

Question 15

Which of the following changes occurs in the distribution of blood flow during strenuous exercise?

Accepted Answer

Blood flow is redirected toward active skeletal muscles and away from non-essential organs.

Question 16

Which of the following is a result of increased sympathetic activity during exercise?

Accepted Answer

Increased heart rate, contractility, and venous constriction.

Question 17

Which of the following best explains the Frank-Starling mechanism in the context of exercise?

Accepted Answer

Increased end-diastolic volume leads to increased stroke volume due to greater stretch of cardiac muscle fibers.

Question 18

Which of the following is NOT a direct effect of sympathetic stimulation on the heart?

Accepted Answer

Decreased heart rate.

Question 19

Which of the following would most likely occur if the baroreceptor reflex failed during acute blood loss?

Accepted Answer

Blood pressure would drop dangerously, risking inadequate perfusion of vital organs.

Question 20

Which of the following is a key difference between parasympathetic and sympathetic effects on the heart?

Accepted Answer

Parasympathetic stimulation decreases heart rate by hyperpolarizing autorhythmic cells; sympathetic stimulation increases heart rate by depolarizing them.

Autonomic Nervous System Regulation of Heart and Circulation

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