Q: A patient with chronic hypertension is found to have increased secretion of aldosterone. What is the primary effect of aldosterone on blood volume, and which equation best describes the relationship between blood pressure, cardiac output, and peripheral resistance?

Aldosterone increases blood volume; $$BP = CO \times PR$$

Question 1

A patient is administered a drug that blocks calcium channels in cardiac contractile cells. Which phase of the cardiac action potential will be most directly affected, and what is the expected effect on the action potential shape?

Accepted Answer

The plateau phase will be shortened due to reduced calcium influx.

Question 2

A patient with chronic hypertension is found to have increased secretion of aldosterone. What is the primary effect of aldosterone on blood volume, and which equation best describes the relationship between blood pressure, cardiac output, and peripheral resistance?

Accepted Answer

Aldosterone increases blood volume; $$BP = CO 	imes PR$$

Question 3

A 60-year-old man presents with a heart rate of 35 beats per minute. Which cardiac pacemaker is most likely controlling his heart rhythm, and why?

Accepted Answer

The Purkinje fibers, because they generate action potentials at approximately 30 beats per minute.

Question 4

During exercise, local tissue levels of $$CO_2$$ increase. What is the expected response of nearby arterioles, and what is the physiological significance of this response?

Accepted Answer

Arterioles dilate, increasing blood flow to remove excess $$CO_2.$$

Question 5

A patient is given a medication that inhibits antidiuretic hormone (ADH) secretion. What is the expected effect on blood volume and why?

Accepted Answer

Blood volume will decrease because less water is reabsorbed in the kidneys.

Question 6

Which of the following best explains why capillaries are the site of the slowest blood flow in the circulatory system?

Accepted Answer

Capillaries have the largest total cross-sectional area, reducing velocity according to $$v = Q/A.$$

Question 7

A patient with liver disease is found to have impaired filtration of blood in the liver. Which type of capillary is primarily affected, and what is a key structural feature of this capillary type?

Accepted Answer

Sinusoid capillaries, which have large gaps between endothelial cells.

Question 8

If a patient’s end-systolic volume (ESV) is decreasing while end-diastolic volume (EDV) remains constant, what is the effect on stroke volume ($$SV$$), and which formula applies?

Accepted Answer

Stroke volume increases; $$SV = EDV - ESV$$

Question 9

A sudden increase in baroreceptor activity is detected. What does this indicate about blood pressure, and what is the expected autonomic response?

Accepted Answer

Blood pressure is high; the parasympathetic system will decrease heart rate.

Question 10

A patient is experiencing low blood pressure. How will the vasomotor fibers respond, and what is the physiological outcome?

Accepted Answer

Vasomotor fiber activity will increase, causing vasoconstriction and raising blood pressure.

Question 11

Which of the following best describes the effect of increased preload on cardiac output, and what is the underlying mechanism?

Accepted Answer

Cardiac output increases due to increased stroke volume via the Frank-Starling law.

Question 12

A patient is diagnosed with aortic valve stenosis, causing left ventricular pressure to be greater than aortic pressure during systole. Which phase of the cardiac cycle is most affected, and what is the consequence for ventricular ejection?

Accepted Answer

Ventricular ejection is impaired, reducing stroke volume.

Question 13

Which hormone(s) will increase blood pressure by causing vasoconstriction, and what is the mechanism?

Accepted Answer

Both antidiuretic hormone and epinephrine increase blood pressure by vasoconstriction.

Question 14

Which layer of a blood vessel is primarily responsible for regulating vessel diameter, and what type of tissue composes this layer?

Accepted Answer

Tunica media; composed of smooth muscle.

Question 15

A patient is found to have a mutation that causes persistent opening of potassium channels in pacemaker cells. What is the expected effect on heart rate, and why?

Accepted Answer

Heart rate will decrease because the cells hyperpolarize, delaying depolarization.

Question 16

During isovolumetric contraction, which of the following statements is true regarding the status of the heart valves and ventricular pressure?

Accepted Answer

Both AV and semilunar valves are closed; ventricular pressure is rising.

Question 17

A patient with severe dehydration has a decreased capillary hydrostatic pressure at the arteriole end. What is the expected effect on fluid movement, and which equation describes net filtration pressure ($$NFP$$)?

Accepted Answer

Less fluid will leave the capillary; $$NFP = (HP_c - HP_i) - (OP_c - OP_i)$$

Question 18

Which of the following best describes the effect of increasing vessel diameter on resistance to blood flow, according to Poiseuille’s law?

Accepted Answer

Resistance decreases; $$R \propto \frac{1}{r^4$}$$

Question 19

A patient is given a drug that increases the frequency of impulses down vasomotor fibers. What is the expected effect on vessel diameter and blood pressure?

Accepted Answer

Vasoconstriction occurs, increasing blood pressure.

Question 20

Which of the following accurately describes the sequence of electrical conduction in the heart immediately before atrial contraction?

Accepted Answer

The SA node undergoes depolarization, initiating atrial contraction.

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