Immune System

Question 1

What does innate immunity do?

Answer 1

Recognizes traits shared by broad ranges of pathogens. Is a rapid response

Question 2

Innate immunity: Barrier Defenses vs Internal defenses

Answer 2

Barrier: skin, mucous membranes, secretions
Internal: Phagocytic cells, natural killer cells, inflammatory response

Question 3

What is adaptive immunity? (Vertebrates only!)

Answer 3

Recognition of traits specific to particular pathogens. A slower response

Question 4

Adaptive immunity: Humoral response vs cell-mediated response

Answer 4

Humoral: Antibodies defend against infection in body fluids
Cell-mediated: Cytotoxic cells defend against infection in the body

Question 5

Local vs Systemic inflammatory response

Answer 5

Local: skin looks red around wound
Systemic: whole body is inflamed (i.e. a fever)

Question 6

What do mast cells release and what does that do?

Answer 6

Mast cells release histamines. Histamines trigger blood vessel dilation

Question 7

What do macrophages release and what does that do?

Answer 7

Macrophages release cytokines. Cytokines are signaling molecules that recruit neutrophils (WBC).

Question 8

What are the two types of phagocytic cells?

Answer 8

Macrophages (certain tissues), and neutrophils (bloodstream)

Question 9

What do antimicrobial proteins (AMP’s) do?

Answer 9

They target pathogens, and usually induce a destructive consequence to the bacteria

Question 10

What is pus?

Answer 10

Remnants of the ‘battleground’. Fluid rich in WBC’s, dead pathogens, and cell debris

Question 11

What does a phagocytic cell do?

Answer 11

Engulfs (eats) pathogens

Question 12

What does the lymphatic system do? (aka Adaptive immune system)

Answer 12

The vessels of the lymphatic system parallel blood vessels, and the lymphatic vessels will take interstitial fluid samples from different places in the body, to search for any pathogens. They circulate fluid called lymph, and bring lymph through lymph nodes.

Question 13

What two types of lymphocytes does adaptive immunity rely on? (What responses do they each take care of?)

Answer 13

B-cells (humoral/antibody-mediated response) and T-cells (cell-mediated)

Question 14

Describe B-cell receptors

Answer 14

Membrane-bound, two binding sites (looks like a Y)

Question 15

Describe T-cell receptors

Answer 15

Membrane-bound, one binding site (straight up and down)

Question 16

What are antigen receptors?

Answer 16

Receptors on B and T cells, each and every cell has a different type of antigen receptor. Millions of lymphocytes each with a different type of receptor.

Question 17

What is the definition of antigen?

Answer 17

Any substance on or secreted by a pathogen that can elicit an immune response

Question 18

What is clonal selection?

Answer 18

The proliferation of B-cells or T-cells that have the antigen receptor that matches the antigen

Question 19

What happens once they find the B-cell that recognizes the antigen? What are the products called?

Answer 19

That B-cell then divides, and makes many copies of itself, called plasma B-cells, which produce antibodies!

Question 20

What are memory B-cells?

Answer 20

Copies of the correct B-cell that are saved, so that the body can remember the antigen in the future.

Question 21

What is neutralization and opsonization?

Answer 21

What antibodies do!
Neutralization - prevent infection by rendering the pathogen useless (surround it)
Opsonization - tag foreign bodies for phagocytosis

Question 22

What is the first step of a T-cell?

Answer 22

They recognize antigen fragments that are presented by an infected host cell. Looks for intracellular pathogens.
(Infected cells and dendritic cells)

Question 23

What are major histocompatibility complexes (MHC)’s?

Answer 23

They present antigen fragments on the surface of the infected host cell, to get T-cells to recognize the antigen. T-cells swap out till one is found with matching antibody.

Question 24

What happens after the correct T-cell is found?

Answer 24

Helper T-cells, that can bind to the antigen, proliferate (multiply) - clonal selection

Question 25

What else do helper T-cells do?

Answer 25

They signal cytotoxic T-cells to come and kill the infected host - to stop replication of the pathogen inside the host cell.
Also memory T-cells are created

Question 26

4 major characteristics of why adaptive immunity is so powerful

Answer 26

1) Diversity of antigen receptors
2) Self-tolerance (will not bind to ourself)
3) B and T cell proliferation after activation
4) Immunological memory - easier to fight off infection that you’ve had in the past, cause your immune system remembers!

Question 27

How is there so much diversity in antigen receptors?

Answer 27

Only a few genes code for them! But gene rearrangement (splicing out parts of DNA) can code for all kinds of combinations of receptors

Question 28

What is a vaccine?

Answer 28

A non pathogenic form of a microbe or part of a microbe that elicits an immune response and immunological memory

Question 29

4 cases when the immune response does not work

Answer 29

1) Immun rejection (organ transplants)
2) Exaggerated response (allergies)
3) Self-directed response (autoimmune conditions)
4) Diminished response (stress, lack of sleep, viral latency)

Question 30

What is a dendritic cell?

Answer 30

A phagocytic cell that consumes a pathogen and then presents is antigen on the surface of its membrane