Topic 13: The Body's Defences (part 2)

Question 1

What is the lymphatic system

Answer 1

a part of the immune system involving one way lymph vessels that carry lymph from tissues back to the blood

Question 2

what is lymph

Answer 2

fluid containing WBCs, plasma, and wastes from blood

Question 3

What are lymph nodes

Answer 3

receive and filter lymph and interact with immune cells

Question 4

What is agglutination

Answer 4

Antibodies that bind multiple antigens (clump together) increases chances of phagocytosis & reduces solubility

Question 5

B-cells

Answer 5

SECRETE ANTIBODIES
mature in bone marrow then concentrate in lymph nodes and spleen
divide into Plasma Cells and Memory B- Cells

Question 6

What is a vaccination

Answer 6

Provides immunity from a pathogen by forcing the body to make memory B cells and/or T cells

Question 7

Describe the humoral immune response

Answer 7

B Cells secrete antibodies; antibodies destroy microbe

Question 8

2 steps of a typical Humoral Response

Answer 8

1. Dendritic cell engulfs an antigen; and presents it on its cell surface
2. In a Lymph node, a B cell attaches and recognizes the Ag
3. B cell is activated and memory cell is made

Question 9

What are antigens

Answer 9

Specific molecules (usually foreign) recognized by antibodies

Question 10

What is neutralization

Answer 10

Neutralize a toxin or pathogen

so that it is unable to bind host cells/tissues

Question 11

What are T-cells and where do they mature

Answer 11

lymphocytes that mature in thymus

Question 12

what are the four types of T-cells?

Answer 12

Cytotoxic T-Cells, Natural Killer T-Cells, Helper T-Cells, Regulatory T-Cells

Question 13

Function of cytotoxic T-cells

Answer 13

Kill other cells with specific antigens

Question 14

Function of Natural killer T-cells

Answer 14

Can recognize and destroy cells infected by viruses

Question 15

Function of helper T-cells

Answer 15

Secrete messages (cytokines) that regulate/activate other immune cells

Question 16

Function of regulatory T-cells

Answer 16

Repress and prevent overactivity of immune cells (from attacking self)

Question 17

What are attenuated vaccines

Answer 17

Uses genetically altered pathogens that are no longer virulent, but can still reproduce

Question 18

What is the cell-mediated immune response

Answer 18

Does not involve antibodies; is the activation of phagocytes and T Cells

Question 19

3 steps of a typical Cell-Mediated Response:

Answer 19

1. Antigen on infected cell’s surface is recognized by T cell
2. T cell gets activated by helper T cell
3. T cell clones itself and becomes or recruits cytotoxic T cells

Question 20

What is an antibody

Answer 20

a molecule which specifically recognizes and binds a particular epitope on an antigen

Question 21

Describe ELISA

Answer 21

Enzyme-Linked ImmunoSorbent Assay

Used to detect the presence of an antigen or antibody in a sample

Question 22

Four steps of ELISA

Answer 22

1. Bind sample to microplate
2. Apply specific antibody
3. Apply 2nd antibody with an enzyme linked to it
4. Add substrate; colour will develop if substrate is consumed

Question 23

What is clonal deletion

Answer 23

The body eliminates self-reactive lymphocytes to prevent attack on self. (Failure can lead to auto-immune diseases).

Question 24

Describe a conjugate vaccine

Answer 24

Vaccine attaches a poor antigen that is easily spotted by the immune system to a strong antigen to elicit a bigger immune response

Question 25

What does opsonization do

Answer 25

stimulates phagocytosis by neutrophils/macrophages

Question 26

What are lymphocytes

Answer 26

specific types of Leukocytes (WBC) that include B and T cells

Question 27

What is a toxoid vaccine

Answer 27

Uses inactivated toxin as the vaccine

Question 28

Describe the five features of adaptive immunity?

Answer 28

1. Specificity - Recognize a particular molecule (antigen) 2. Inducibility - Cells get activated only in response to specific pathogens 3. Clonality - Active cells duplicate themselves (clones) 4. No response to self - The immune system doesn’t attack its own body 5. Memory - The immune system remembers and reacts faster during a second exposure to pathogen

Question 29

Describe the five components of adaptive immunity?

Answer 29

1. lymphatic system 2. antigens 3. antibodies 4. lymphocytes (B+T cells) 5. chemical signals + mediators - cytokines, interleukins + more chemical messengers that send messages between immune cells

Question 30

Distinguish between antibody, antigen, and epitope.

Answer 30

antigen - used to recognize foreign things antibody - bind to antigens epitope - The specific region of an antigen which is bound by a specific antibody (there may be several per antigen)

Question 31

Describe four functions of antibodies.

Answer 31

1. opsonization - induces phagocytosis 2. antibody- dependent cellular cytokinesis - non-phagocytotic killing mediated by natural killer cells, neutrophils and eosinophils 3. active complement system - enhances opsonization and lyses some bacteria 4. agglutination - clumping of pathogen creating large complex. increases recognition/phagocytosis

Question 32

Compare and contrast humoral immunity and cell-mediated immunity.

Answer 32

humoral - small microbes, macromolecules | cell-mediated - large parasites, intercellular pathogens, tumors

Question 33

Why is there no vaccine for the common cold?

Answer 33

Over 200 know strains! Many of them mutate from season to season!

Question 34

Why do we have a new flu vaccine each year?

Answer 34

Virus mutates and new strains arise each year requiring new vaccines

Question 35

What are the four types of vaccines?

Answer 35

attenuated, killed/inactivated, subunit/conjugate, toxoid

Question 36

killed/inactivated vaccines

Answer 36

microbe is killed or deactivated and cannot replicate or cause disease but can still train immune system (make memory cells)

Question 37

Role of memory B cells

Answer 37

Memory B cells remain in the body to speed up the response if the same antigen reappears