Question 1

Which layer of the blood vessel wall is primarily responsible for vasoconstriction and vasodilation?

Accepted Answer

Tunica media

Question 2

Arteries are often referred to as 'pressure reservoirs.' What structural feature allows them to fulfill this function?

Accepted Answer

Abundant elastic fibers in the tunica media

Question 3

Which of the following best describes the function of capillaries in the circulatory system?

Accepted Answer

They serve as exchange vessels for nutrients, gases, and wastes.

Question 4

Veins are described as capacitance vessels. What does this mean?

Accepted Answer

They contain most of the blood volume and act as blood reservoirs.

Question 5

Blood flow ($Q$) through a vessel is determined by the pressure difference ($\Delta P$) and resistance ($R$). Which equation correctly expresses this relationship?

Accepted Answer

$Q = \Delta P / R$

Question 6

According to Poiseuille’s Law, which variable has the greatest effect on resistance to blood flow in a vessel?

Accepted Answer

Vessel radius ($r$)

Question 7

A patient has a blood pressure of 120/80 mmHg. What is their mean arterial pressure (MAP)? Use the formula $MAP = 	ext{diastolic BP} + \frac{1}{3}(	ext{systolic BP} - 	ext{diastolic BP})$.

Accepted Answer

MAP = 80 + \frac{1}{3}(120 - 80) = 80 + 13.3 = 93.3 mmHg

Question 8

Which mechanism is most important for venous return to the heart during exercise?

Accepted Answer

Muscular pump (skeletal muscle contraction)

Question 9

Which of the following would most likely increase total peripheral resistance (TPR) and thus raise mean arterial pressure (MAP)?

Accepted Answer

Vasoconstriction of arterioles

Question 10

A patient with severe liver disease develops pitting edema. Which mechanism best explains this finding?

Accepted Answer

Decreased plasma protein concentration leading to reduced colloid osmotic pressure

Question 11

Which of the following hormones is released in response to increased blood volume and promotes vasodilation and natriuresis?

Accepted Answer

Atrial natriuretic peptide (ANP)

Question 12

During a sudden drop in blood pressure, which reflex is activated to restore homeostasis?

Accepted Answer

Baroreceptor reflex

Question 13

Which of the following best describes the effect of sympathetic stimulation on most systemic arterioles?

Accepted Answer

Vasoconstriction via norepinephrine release

Question 14

Bulk flow across capillary walls is primarily driven by which two forces?

Accepted Answer

Capillary hydrostatic pressure and plasma colloid osmotic pressure

Question 15

Which type of capillary is most permeable and found in organs such as the liver and bone marrow?

Accepted Answer

Sinusoid capillary

Question 16

If the radius of a blood vessel doubles, how does the resistance to flow change according to Poiseuille’s Law ($R \propto \frac{1}{r^4}$)?

Accepted Answer

Resistance decreases by a factor of 16

Question 17

Which of the following is a direct effect of increased sympathetic activity on the heart?

Accepted Answer

Increased force of contraction

Question 18

A patient is experiencing hypovolemic shock after severe blood loss. Which compensatory mechanism is most likely to be activated first?

Accepted Answer

Baroreceptor-mediated increase in sympathetic tone

Question 19

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

Accepted Answer

$MAP = CO 	imes TPR$

Question 20

Which of the following would most likely occur in a tissue with increased metabolic activity?

Accepted Answer

Local vasodilation due to increased CO$_2$ and decreased pH

Blood Vessels: Structure, Function, and Physiology (Anatomy & Physiology Study Notes)

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