lec 3 exam

Question 1

What are endotoxins?

Answer 1

Toxic components of the outer membrane of Gram-negative bacteria

Example: Lipopolysaccharides from E. coli

Question 2

What are exotoxins?

Answer 2

Toxins secreted by bacteria into the surrounding environment

Example: Diphtheria toxin from Corynebacterium diphtheriae

Question 3

Name a carcinogenic fungal toxin.

Answer 3

Aflatoxins (Aspergillus species)

Carcinogenic compounds produced by certain fungi

Question 4

What are saxitoxins?

Answer 4

Neurotoxins produced by dinoflagellates causing paralytic shellfish poisoning

Question 5

Which bacteria causes botulism?

Answer 5

Clostridium botulinum (exotoxin)

Question 6

What is toxemia?

Answer 6

The presence of toxins in the bloodstream, leading to systemic illness

Question 7

What are neutrophils?

Answer 7

Main phagocytic cells; first responders to infection

Question 8

What is phagocytosis?

Answer 8

The process by which cells (e.g., macrophages) engulf and digest pathogens

Question 9

Define antigenic variation.

Answer 9

The ability of a pathogen to alter its surface proteins to evade the host immune response

Question 10

What are physical factors of the first line of defense?

Answer 10

Skin, mucous membranes, and the normal microbiota

Question 11

What are epitopes?

Answer 11

Specific parts of an antigen recognized by antibodies or T-cell receptors

Question 12

What is the function of siderophores?

Answer 12

Molecules produced by bacteria to scavenge iron from the host

Question 13

What is the definition of innate immunity?

Answer 13

Non-specific defense mechanisms present at birth (e.g., skin, phagocytes)

Question 14

What is active immunity?

Answer 14

Develops after exposure to an antigen (natural infection or vaccination)

Question 15

What is selective toxicity?

Answer 15

The ability of a drug to target pathogens without harming the host’s cells

Question 16

What are TLRs?

Answer 16

Pattern recognition receptors on immune cells that detect PAMPs

Question 17

What is the difference between bactericidal and bacteriostatic?

Answer 17

Bactericidal kills bacteria; bacteriostatic inhibits bacterial growth

Question 18

What are the different classes of antibodies?

Answer 18

• IgG
• IgM
• IgA
• IgE
• IgD

Question 19

What is the role of helper T cells (CD4+)?

Answer 19

Assist in activating B cells and cytotoxic T cells

Question 20

What is the function of cytotoxic T cells (CD8+)?

Answer 20

Directly kill infected or cancerous cells

Question 21

What is class switching in B cells?

Answer 21

The process by which B cells change the class of antibody they produce

Question 22

What are cytokines?

Answer 22

Signaling molecules that mediate and regulate immunity, inflammation, and hematopoiesis

Question 23

Define humoral immunity.

Answer 23

Immune response involving B cells that produce antibodies to eliminate pathogens

Question 24

What is the definition of cell-mediated immunity?

Answer 24

Immune response mediated by T cells targeting and destroying infected cells

Question 25

What is the definition of interferons?

Answer 25

Cytokines that play a role in the immune response against viruses

Question 26

What is the role of macrophages?

Answer 26

Engulf and digest pathogens; differentiate from monocytes

Question 27

What are the formed elements of blood?

Answer 27

* Red blood cells (erythrocytes) * White blood cells (leukocytes) * Platelets

Question 28

What is the function of APCs?

Answer 28

Present antigens to T cells, initiating the adaptive immune response

Question 29

What is the definition of cytokine storm?

Answer 29

An overproduction of cytokines leading to severe inflammation and tissue damage

Question 30

What is the definition of hematopoiesis?

Answer 30

The formation of blood cellular components from hematopoietic stem cells in the bone marrow

Question 31

What is the outcome of complement activation?

Answer 31

Opsonization, inflammation, and cell lysis

Question 32

What is the difference between broad-spectrum and narrow-spectrum antibiotics?

Answer 32

Broad-spectrum is effective against a wide variety of bacteria; narrow-spectrum is effective against specific types

Question 33

What are mechanisms of resistance of bacteria against antimicrobial drugs?

Answer 33

* Enzymatic degradation * Alteration of drug targets * Reduction of permeability * Efflux pumps

Question 34

What are the cytopathic effects of viral infection?

Answer 34

Visible changes in host cells due to viral replication, leading to cell dysfunction or death

Question 35

What are the different types of leukocytes?

Answer 35

* Neutrophils * Lymphocytes * Monocytes * Basophils * Eosinophils

Question 36

What is the definition of invasins?

Answer 36

Bacterial proteins that promote entry and spread through host tissues

Question 37

What are the two main types of T cells?

Answer 37

* Helper T cells * Cytotoxic T cells

Question 38

What is the definition of toxoids?

Answer 38

Inactivated toxins used in vaccines to stimulate an immune response without causing disease