Q: Which of the following is the correct formula for mean arterial pressure (MAP) using systolic and diastolic blood pressure?

$$MAP = \text{Diastolic pressure} + \dfrac{1}{3}(\text{Systolic pressure} - \text{Diastolic pressure})$$

Question 1

Which of the following best explains why cardiac muscle cells are able to contract as a coordinated unit, unlike skeletal muscle fibers?

Accepted Answer

Cardiac muscle cells are connected by gap junctions, allowing rapid electrical communication.

Question 2

A patient presents with a heart rate of 45 beats per minute and an ECG showing absent P waves. Which structure is most likely pacing the heart?

Accepted Answer

Atrioventricular (AV) node

Question 3

During the plateau phase of the ventricular contractile cell action potential, which ionic movement is primarily responsible for maintaining the membrane potential?

Accepted Answer

Influx of $$\mathrm{Ca$$^{2+}$$}$$ ions through L-type calcium channels

Question 4

Which of the following equations correctly calculates cardiac output (CO)?

Accepted Answer

$$CO = HR 	imes SV$$

Question 5

A patient has an end-diastolic volume (EDV) of 130 mL and an end-systolic volume (ESV) of 60 mL. What is their stroke volume (SV)?

Accepted Answer

$$SV = EDV - ESV = 70\ \mathrm{mL}$$

Question 6

Which of the following best describes the effect of increased venous return on stroke volume, according to the Frank-Starling law?

Accepted Answer

Stroke volume increases because increased EDV stretches cardiac muscle fibers, enhancing contraction.

Question 7

Which of the following is the correct formula for mean arterial pressure (MAP) using systolic and diastolic blood pressure?

Accepted Answer

$$MAP = 	ext{Diastolic pressure} + \dfrac{1}{3}(	ext{Systolic pressure} - 	ext{Diastolic pressure})$$

Question 8

According to Poiseuille’s law, which factor has the greatest effect on total peripheral resistance (TPR) in the circulatory system?

Accepted Answer

Vessel radius

Question 9

A patient is given a drug that blocks $$\$$beta_1$$-adrenergic receptors in the heart. What is the expected effect on cardiac output (CO)?

Accepted Answer

CO will decrease due to decreased heart rate and contractility.

Question 10

Which of the following best explains why blood flow is slowest in the capillaries?

Accepted Answer

Capillaries have the highest total cross-sectional area.

Question 11

A patient with severe aortic stenosis has increased afterload. Which of the following changes would you expect in their left ventricular function?

Accepted Answer

Decreased stroke volume and increased end-systolic volume.

Question 12

Which of the following best describes the baroreceptor reflex in response to a sudden drop in blood pressure?

Accepted Answer

Increased sympathetic activity increases heart rate and vasoconstriction.

Question 13

Which of the following ECG findings is most consistent with second-degree heart block (Mobitz type I)?

Accepted Answer

Progressive lengthening of the PR interval until a QRS complex is dropped.

Question 14

Which of the following best describes the movement of fluid in edema due to heart failure?

Accepted Answer

Fluid moves from the capillaries into the interstitium.

Question 15

Which of the following is a positive inotropic agent that increases cardiac contractility?

Accepted Answer

Norepinephrine

Question 16

A patient’s blood pressure is measured as 120/80 mmHg. What is their pulse pressure?

Accepted Answer

$$120\ \mathrm{mmHg} - 80\ \mathrm{mmHg} = 40\ \mathrm{mmHg}$$

Question 17

Which of the following best describes the function of the Circle of Willis?

Accepted Answer

It allows alternate pathways for cerebral blood flow if a major artery is blocked.

Question 18

Which of the following changes would most likely occur in a patient experiencing anaphylactic shock?

Accepted Answer

Decreased TPR due to widespread vasodilation.

Question 19

Which of the following best explains why the AV node is critical in the electrical conduction system of the heart?

Accepted Answer

It delays the electrical impulse, allowing the atria to contract before the ventricles.

Question 20

Which of the following best describes the effect of acetylcholine on the heart?

Accepted Answer

It decreases heart rate by increasing $$\mathrm{K^+}$$ efflux in pacemaker cells.

Cardiovascular System: Anatomy & Physiology Study Guide (Chapters 18 & 19)

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