Immunity

Question 1

What are the two types of adaptive immunity?

Answer 1

Humoral immunity and Cell-mediated immunity.

Question 2

What is the main defense mechanism in humoral immunity?

Answer 2

Production of antibodies.

Question 3

What is the main defense mechanism in cell-mediated immunity?

Answer 3

Activation of T cells to destroy intracellular antigens.

Question 4

Which cells are responsible for humoral immunity?

Answer 4

B lymphocytes.

Question 5

Which cells are responsible for cell-mediated immunity?

Answer 5

T lymphocytes.

Question 6

Where do T lymphocytes mature?

Answer 6

In the thymus.

Question 7

Where do B lymphocytes mature?

Answer 7

In the bone marrow.

Question 8

What are the primary lymphoid organs?

Answer 8

Bone marrow and thymus.

Question 9

What are the secondary lymphoid organs?

Answer 9

Lymph nodes, spleen, and aggregated lymphoid tissue (e.g., tonsils).

Question 10

How do lymphocytes recognize antigens?

Answer 10

Each lymphocyte has a specific surface receptor for a unique antigen.

Question 11

What happens when a B cell encounters its specific antigen?

Answer 11

It binds, proliferates, and differentiates into plasma cells and memory cells.

Question 12

What do plasma cells do?

Answer 12

Secrete antibodies specific to the antigen.

Question 13

What are the five classes of antibodies?

Answer 13

IgA, IgD, IgE, IgG, IgM.

Question 14

Which antibody is most abundant during the primary immune response?

Answer 14

IgM.

Question 15

Which antibody is most abundant during the secondary immune response?

Answer 15

IgG.

Question 16

Which antibody can crossthe placenta?

Answer 16

IgG.

Question 17

What is the role of IgA?

Answer 17

Protects mucosal surfaces by forming antigen-antibody complexes that cannot be absorbed.

Question 18

What is the role of IgE?

Answer 18

Involved in allergic responses; found in low concentrations in blood.

Question 19

What is the role of IgD?

Answer 19

Found on B cell membranes; involved in B cell activation.

Question 20

What is the key difference between a primary and secondary immune response?

Answer 20

Secondary response is faster and stronger due to memory cells.

Question 21

Why is the secondary immune response faster?

Answer 21

Because of immunologic memory.

Question 22

Can T cells recognize antigens directly?

Answer 22

No, they require antigen presentation via MHC molecules.

Question 23

What are the two major types of effector T cells?

Answer 23

Helper T cells and Cytotoxic T cells.

Question 24

What do Helper T cells do?

Answer 24

Express CD4 and secrete cytokines to activate other immune cells.

Question 25

What do Cytotoxic T cells do?

Answer 25

Express CD8 and kill infected or altered self cells.

Question 26

What do Regulatory T cells do?

Answer 26

Suppress the immune response to maintain immune balance.

Question 27

What happens if Regulatory T cells fail to function properly?

Answer 27

Autoimmune disorders may develop.

Question 28

What are the three main functions of the complement system?

Answer 28

Mediate inflammation, opsonize pathogens, form membrane attack complexes.

Question 29

How does the complement system enhance phagocytosis?

Answer 29

By coating the surface of bacteria (opsonization).

Question 30

What is the membrane attack complex (MAC)?

Answer 30

A structure formed by complement proteins that punches holes in target cell membranes.