Question 1

Which layer of a blood vessel is primarily responsible for regulating vessel diameter and blood pressure?

Accepted Answer

Tunica media

Question 2

Elastic arteries play a crucial role in maintaining diastolic blood pressure. If the elasticity of these arteries decreases due to aging, what is the most likely physiological consequence?

Accepted Answer

Decrease in diastolic blood pressure

Question 3

Which of the following best describes the function of venous valves?

Accepted Answer

They prevent the backflow of blood and ensure unidirectional flow toward the heart.

Question 4

A patient presents with edema in the lower limbs. Which malfunction in the venous system is most likely responsible?

Accepted Answer

Failure of venous valves leading to blood pooling

Question 5

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

Accepted Answer

Discontinuous endothelium

Question 6

Blood flow through capillary beds is regulated by which of the following structures?

Accepted Answer

Precapillary sphincters

Question 7

Which of the following is NOT a function of the complement system in immune defense?

Accepted Answer

Neutralizing toxins by binding to them

Question 8

A B lymphocyte is exposed to its specific antigen for the first time. What is the correct sequence of events that follows?

Accepted Answer

Activation, proliferation, differentiation into plasma cells and memory cells

Question 9

Which class of lymphocyte is primarily responsible for killing virus-infected and tumor cells that have downregulated MHC I molecules?

Accepted Answer

Natural killer (NK) cells

Question 10

Which of the following best explains why cytotoxic T cells require antigen presentation by MHC I molecules?

Accepted Answer

MHC I molecules present intracellular antigens, allowing cytotoxic T cells to recognize and kill infected or cancerous cells.

Question 11

Which equation best represents the relationship between blood flow ($Q$), pressure difference ($\Delta P$), and resistance ($R$) in a vessel?

Accepted Answer

$Q = \dfrac{\Delta P}{R}$

Question 12

Which of the following is a primary lymphatic organ responsible for lymphocyte development?

Accepted Answer

Thymus

Question 13

A histological section of a lymph node shows a lightly stained germinal center surrounded by a darker mantle zone. What does this indicate?

Accepted Answer

A secondary follicle with active B cell proliferation

Question 14

Which of the following statements about lymphatic vessels is TRUE?

Accepted Answer

They contain valves to ensure unidirectional lymph flow.

Question 15

Which immune cell type is most abundant in the paracortex of a lymph node?

Accepted Answer

T lymphocytes

Question 16

A patient with HIV has a reduced number of CD4+ T cells. Which aspect of immune function is most compromised?

Accepted Answer

Activation of B cells and coordination of immune responses

Question 17

Which of the following best describes the role of antigen-presenting cells (APCs) in adaptive immunity?

Accepted Answer

They present antigen fragments with MHC molecules to T cells, initiating their activation.

Question 18

Which of the following is a correct statement about the structure of arteries compared to veins?

Accepted Answer

Arteries have a thicker tunica media than veins.

Question 19

Which of the following is a function of lymph nodes?

Accepted Answer

Filtering lymph and facilitating immune responses

Question 20

If a patient has a genetic defect preventing the formation of the membrane attack complex (MAC) in the complement system, which process would be most affected?

Accepted Answer

Direct lysis of pathogens

Human Biology & Histology: Structure and Function of Blood Vessels and the Immune System

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