6 Immunity

Question 1

Role of the skin as a barrier.

Answer 1

Physical

-waxy and waterproof due to keratin

Question 2

Role of stomach acid as a barrier.

Answer 2

Chemical

• low pH which kills bacteria
• Hydrochloric acid

Question 3

Role of gut flora.

Answer 3

Helps exclude bad bacteria

Question 4

Role of skin flora.

Answer 4

Takes up space outcompete pathogen

Question 5

What are the three features of an inflammatory response?

Answer 5

Swelling, pus, redness

Question 6

Describe the process of an inflammatory response.

Answer 6

• foreign antigen recognised
• mast cells release histamine
• histamine increases blood flow
• capillaries dilate no become leaky
• platelets promote clotting and stop pathogens spreading
• dead/used wbc make pus

Question 7

Describe the process of phagocytosis (REPLEE)

Answer 7

Recognise- foreign pathogen recognised from its antigen
Engulf- pathogen engulfed by endocytosis
Phagosome- invagination of plasma membrane= phagosome formed
Lysosome- phagosome+ lysosome fuse = phagolysosome
Enzymes- hydrolytic enzymes (lysoSYME and protease) digest pathogen
Exocytosis- remove harmless product

Question 8

Describe interferon action. (virus only)

Answer 8

• virus invades cell= cell releases interferons (proteins)
• interferons diffuse from cell
• binds to nearby receptors on outsides of cells
• stimulates a pathway to inhibit protein synthesis and stop viral replication

also promotes inflamation

Question 9

What is the goal of interferon action in short.

Answer 9

prevent viral replication by signalling (inteferons presented on outside of cells)

Question 10

what is a lysosome?

Answer 10

membrane-bound sac containing hydrolytic enzymes

Question 11

name two hydrolytic enzymes:

Answer 11

lysosYme and protease

Question 12

what are antigens?

Answer 12

molecules on the surface of cells that can bind to specific antibodies

Question 13

what are antibodies?

Answer 13

Y shaped proteins that recognise and bind antigens

Question 14

what type of proteins are antibodies?produced by?

Answer 14

glycolic-proteins made by WBCs

Question 15

describe the structure of an antibody.

Answer 15

• 4 polypeptide chains, 2 light on outside and heavy on the inside
• variable portion on tips rest is constant

Question 16

what makes antibodies specific?

Answer 16

the variable portion allows flexibility to certain antigens

Question 17

how are antibodies produced?

Answer 17

secreted by plasma cells and cloned once right shape is identified

Question 18

describe the role of antibodies.

Answer 18

• bind to antigens on bacterias surface-labelling it as foreign
• antibodies clump together due to Y shape (agglutination)
• antibody binds to antibody receptor on macrophages
• macrophage now easily engulfs all bacteria

Question 19

3 ways antibodies help clear infections: NAP

Answer 19

Neutralising toxins- bind to prevent effect
Agglutinating pathogens- 2 binding sites on each (Y)
Preventing pathogens from binding to cells

Question 20

Role of B-Memory cells is …

Answer 20

to remember previous pathogens for a fast immune response in the future

Question 21

Role of B-effector cells is …

Answer 21

to differentiate in plasma cells which produce the specific antibody

Question 22

Role of T-helper cells is …

Answer 22

t helper clones release cytokines to activate clonal selection of B cells before they differentiate

Question 23

Role of T-Memory cells is …

Answer 23

to create a faster stronger response to previous pathogens

Question 24

Role of T-killer cells is …

Answer 24

• to bind to cells making them APCs
• active t killer cells bind to APCs creating pores to allow water and ions to move in via osmosis to cause LYSIS, pathogens release are phagocytosed

Question 25

what are APCs?

Answer 25

antigen presenting cells digest pathogens, signalling to other cells an immune response

Question 26

how can different types of antibodies come about?

Answer 26

alternative splicing | -exons are rearranged to a new sequence to make new combinations therefore new proteins form

Question 27

what is MHC II?

Answer 27

major histocompatibility complex II are genes found on the surface of APCs (only) that will code for cell surface membrane proteins that will PRESENT A SMALL PART OF THE FOREIGN ANTIGEN to help distinguish between foreign and own cells

Question 28

what is MHC I?

Answer 28

found on all body cells

Question 29

how can you develop natural active immunity?eg.

Answer 29

-body makes antibodies through immune response after being expose to a pathogen eg colds

Question 30

how can you develop artificial active immunity?eg.

Answer 30

- exposed to antigen by injection into the body so body then reacts with an immune reponse eg. vaccinations

Question 31

how can you develop natural passive immunity?eg.

Answer 31

-woman who is ill passes antibodies to child via umbilical cord while in womb or via milk after

Question 32

how can you develop artificial passive immunity?eg.

Answer 32

-injected with antibodies, body cannot produce them

Question 33

explain how vaccines can give you immunity.

Answer 33

-imitate infection by being exposed to either a dead pathogen or weakened version o fit our body should recognise its antigens as foreign and begin an immune response to develop antibodies and memory cells to create a fast recovery if ver infected.

Question 34

why are weakened pathogens better than dead ones for vaccines?

Answer 34

- more closely resemble real infection | - Immunity is longer lasting

Question 35

what are the dangers of vaccines? main issue?

Answer 35

- side effects - larger impact on immune system than intended, infection from other pathogens is more succeptable - vaccines target specific proteins so if pathogen mutates and antigens change then they are no longer useful