Exam . 3

Question 1

What is the third line of defense in the immune system?

Answer 1

Adaptive immunity

The immune system has three lines of defense: physical barriers (skin, mucous membranes), innate immunity (inflammatory response), and adaptive immunity.

Question 2

What molecules stimulate a response by T and B cells?

Answer 2

Antigens

Antigens are substances that induce an immune response, specifically activating T and B lymphocytes.

Question 3

What characteristic feature allows lymphocytes to respond rapidly to subsequent encounters with an antigen?

Answer 3

Memory

Memory is a key feature of the adaptive immune system, enabling quicker responses upon re-exposure to the same antigen.

Question 4

Which receptors are involved in recognizing self molecules and rejection of foreign tissue?

Answer 4

Major Histocompatibility Complex (MHC)

MHC molecules play a crucial role in the immune system by presenting antigens to T cells.

Question 5

MHC class I receptors are found on which cells?

Answer 5

All nucleated cells

MHC class I molecules are present on virtually all nucleated cells and present endogenous antigens to CD8 T cells.

Question 6

MHC class II receptors are restricted to which type of cells?

Answer 6

Immune cells

MHC class II molecules are primarily found on professional antigen-presenting cells, such as dendritic cells, macrophages, and B cells.

Question 7

Where do T cells mature?

Answer 7

Thymus

T cells originate in the bone marrow but migrate to the thymus for maturation.

Question 8

What do T-cell receptors bind to?

Answer 8

Processed antigens with MHC molecules

T-cell receptors specifically recognize antigens that are presented by MHC molecules on the surface of other cells.

Question 9

What are the two polypeptide chains in the most common T-cell receptor?

Answer 9

Alpha and beta chains

Most T-cell receptors consist of an alpha and a beta chain, crucial for antigen recognition.

Question 10

CD4 T cells are also known as:

Answer 10

Helper T cells

CD4 T cells play a key role in assisting other immune cells, such as B cells and cytotoxic T cells.

Question 11

What process coats microorganisms with antibodies so they are more readily recognized by phagocytes?

Answer 11

Opsonization

Opsonization enhances phagocytosis by marking pathogens for destruction by immune cells.

Question 12

Which immunoglobulin class is involved in allergic responses and parasitic worm infections?

Answer 12

IgE

IgE is primarily associated with allergic reactions and defense against parasitic infections.

Question 13

Which immunoglobulin is the most prevalent in the blood?

Answer 13

IgG

IgG makes up about 75-80% of the total immunoglobulin in serum.

Question 14

Which cells are responsible for the secondary immune response?

Answer 14

Memory cells

Memory cells are long-lived and enable a faster and more effective response upon re-exposure to the same antigen.

Question 15

What is an antigenic determinant?

Answer 15

The part of the antigen that is recognized by lymphocytes

Antigenic determinants, also known as epitopes, are crucial for the specificity of the immune response.

Question 16

Which type of immunity involves the transfer of preformed antibodies?

Answer 16

Passive immunity

Passive immunity can be naturally acquired (e.g., through maternal antibodies) or artificially acquired (e.g., through antibody injections).

Question 17

Which immunoglobulin class is the first to respond to an infection?

Answer 17

IgM

IgM is typically produced first during an immune response and is crucial for initial defense.

Question 18

What type of cells are activated by MHC class I molecules?

Answer 18

Cytotoxic T cells

MHC class I molecules present endogenous antigens to CD8+ T cells, triggering a cytotoxic response.

Question 19

What is the role of granzymes in the immune response?

Answer 19

Induce apoptosis

Granzymes are serine proteases that enter target cells and trigger programmed cell death.

Question 20

Which type of T cells help other cells by secreting cytokines?

Answer 20

Helper T cells

Helper T cells (CD4+ T cells) play a critical role in orchestrating the immune response by activating B cells and cytotoxic T cells.

Question 21

What is the main function of B-cell receptors?

Answer 21

Bind free antigens

B-cell receptors are membrane-bound immunoglobulins that recognize and bind to specific antigens.

Question 22

What happens to plasma cells after an infection has passed?

Answer 22

They undergo apoptosis

Most plasma cells die off once the infection is cleared, although some may become memory B cells.

Question 23

Which immunoglobulin can cross the placenta to provide passive immunity to the fetus?

Answer 23

IgG

IgG is the only immunoglobulin class that can cross the placenta, providing the fetus with immunity.

Question 24

What process involves antibodies binding to pathogens?

Answer 24

Opsonization, Neutralization, Complement fixation, Agglutination

These processes enhance the immune response by marking pathogens for destruction.

Question 25

Which cells are primarily responsible for the production of antibodies?

Answer 25

B cells, Plasma cells

Plasma cells are differentiated B cells that secrete antibodies.

Question 26

What is the term for a substance that provokes an immune response?

Answer 26

Antigen

Antigens can be proteins, polysaccharides, or other molecules that are recognized by the immune system.

Question 27

Which immunoglobulin is found in mucous and serous secretions?

Answer 27

IgA

IgA plays a crucial role in mucosal immunity.

Question 28

What type of immunity is acquired through vaccination?

Answer 28

Artificial active immunity

This immunity results from exposure to a vaccine that stimulates the immune system.

Question 29

Which cells present antigens to T cells?

Answer 29

B cells, Macrophages, Dendritic cells

These cells are known as antigen-presenting cells (APCs).

Question 30

What do memory cells do during a secondary immune response?

Answer 30

Produce antibodies immediately

Memory cells enable a faster and more effective immune response upon re-exposure to the same antigen.

Question 31

What is the primary function of CD8 T cells?

Answer 31

Kill infected cells

CD8 T cells are also known as cytotoxic T lymphocytes.

Question 32

What type of cells are involved in the anamnestic response?

Answer 32

Memory cells

The anamnestic response is a rapid and robust immune response due to the presence of memory cells.

Question 33

Which immunoglobulin is primarily responsible for the initial defense in the gut and respiratory tract?

Answer 33

IgA

IgA helps prevent infection at mucosal surfaces.

Question 34

Which type of cells secrete cytokines to help activate B cells?

Answer 34

Helper T cells

Helper T cells play a critical role in coordinating the immune response.

Question 35

Which part of the immunoglobulin molecule binds to antigens?

Answer 35

Variable region

The variable region of an antibody is responsible for its specificity to a particular antigen.

Question 36

What does the process of affinity maturation result in?

Answer 36

Increased antibody specificity

Affinity maturation enhances the ability of antibodies to bind more effectively to their specific antigens.

Question 37

Which cells are primarily responsible for killing virus-infected cells?

Answer 37

Cytotoxic T cells

Cytotoxic T cells directly destroy virus-infected cells and are essential for the adaptive immune response.

Question 38

What type of molecule is a hapten?

Answer 38

A small foreign molecule

Haptens are typically too small to elicit an immune response on their own but can trigger one when attached to a larger carrier protein.

Question 39

What type of immune response is triggered by superantigens?

Answer 39

Overwhelming immune response

Superantigens can activate a large number of T cells, leading to a massive release of cytokines and a strong immune reaction.

Question 40

What is the function of regulatory T cells?

Answer 40

Suppress the immune response

Regulatory T cells help maintain immune tolerance and prevent autoimmune reactions.

Question 41

Which immunoglobulin class serves as a B-cell receptor for antigen on B cells?

Answer 41

IgD

IgD is primarily found on the surface of B cells and plays a role in the initiation of B cell activation.

Question 42

What is the role of cytokines in the immune system?

Answer 42

Mediate communication between cells

Cytokines are signaling molecules that facilitate interactions and coordination between different immune cells.

Question 43

Which process involves the activation of the classical complement pathway?

Answer 43

Complement fixation

Complement fixation is a key step in the classical pathway that enhances the ability to clear pathogens from the body.

Question 44

What type of cells differentiate into plasma cells?

Answer 44

Naive B cells

When activated by an antigen, naive B cells can differentiate into plasma cells that produce antibodies.

Question 45

Which cells are involved in the regulation of the immune response?

Answer 45

Regulatory T cells

Regulatory T cells play a crucial role in controlling and modulating the immune response.

Question 46

Which immunoglobulin is involved in the primary response to an antigen?

Answer 46

IgM

IgM is the first antibody produced in response to an antigen, playing a critical role in the initial immune response.

Question 47

What is the main function of cytotoxic T cells?

Answer 47

Kill infected cells

Cytotoxic T cells are essential for targeting and destroying cells that are infected by pathogens.