Immune System

Question 1

Innate / Natural Immunity

Answer 1

Non-specific: Cells involved cannot differentiate between types of micro-organisms
Non-adaptive: Response is the same regardless of the number of times the host is infected

Question 2

Adaptive / Acquired Immunity

Answer 2

Specific: Cells involved can differentiate between types of micro-organisms
Memory: Cells can produce an enhanced response to repeated infections

Question 3

Phagocytes

Answer 3

engulf & digest pathogens (endocytosis)

Question 4

Monocytes/macrophages

Answer 4

engulf & destroy bacteria

Question 5

Neutrophils

Answer 5

scavengers that circulate in blood. Die to form pus.

Question 6

Dendritic Cells

Answer 6

take samples (antigens) to the 3rd line of defence

Question 7

Mast Cells

Answer 7

activated by contact with antigens. Secrete histamine which causes vasodilation (wider blood vessels) and increased blood vessel permeability to allow more cells and fluid to reach the area needed.

Question 8

Symptoms of inflammation

Answer 8

-Swelling – caused by increase cells & fluid in the area affected.
-Redness – caused by increased blood flow through nearby blood vessels.
-Heat - caused by increased blood flow through nearby blood vessels + increased friction due to cell & chemical movement.
-Pain – caused by swelling putting pressure on nerves in area.

Question 9

How does a fever help with fighting pathogens?

Answer 9

Increases environmental temperature above optimum for pathogens
If pathogens grow slowly= body’s defenses have a better chance!

Question 10

How does blood clotting by platelets work?

Answer 10

They clump together in order to form a plug at broken section of vessel

Question 11

Dendritic Cells

Answer 11

whole job is to take ‘samples’ of foreign substances (antigens)

then travel to lymphatic system to activate 3rd line of defence

Question 11

Eosinophils

Answer 11

have powerful enzymes that destroy pathogens. Big players in parasite infections. Often seen in asthma & cause a lot of tissue damage due to inflammation.

Question 12

Natural Killer Cells

Answer 12

NK cells (Natural Killer): patrol body & find cells infected with viruses or cancer cells.

Recognise changes in MHC on self cells.

Cytotoxic (kills cells) & non-specific

Like T-cells of specific system but don’t require activation.

Act by releasing perforin which breaks membrane of infected cell.

Also trigger cytokine release = attracts macrophages.

Question 13

Basophils

Answer 13

Important in allergic responses (asthma, anaphylaxis, hay fever). Main function = release of granules of histamine (opens blood vessels) & heparin (prevents blood clotting). Major part of inflammatory reaction.

Question 14

Histamine

Answer 14

a chemical released by many cells. Causes swelling & pain but the point is to increase blood flow to injury site to get more WBCs and chemicals there!

Question 15

Antigen

Answer 15

toxin or other foreign substance which induces an immune response (especially production of antibodies)

Question 16

Antibody

Answer 16

Y-shaped blood protein produced in response to a specific antigen.

Question 17

T-helper

Answer 17

Bind to antigen/MHCII complex presented by B-cells
Activate T-cytotoxic cells & B-cells

Question 18

Cytotoxic/Kiler T-cells

Answer 18

Go around checking MHCI on surface of cells
If cell has been invaded it will show a foreign antigen = killed

Question 19

Memory T-cells

Answer 19

Remain after the pathogens have been killed to stop re-infection (by storing data about the antigens)

Question 20

Suppressor T-cells

Answer 20

These basically are the off switch for the immune system, they come into play when the antigens have been dealt with.

Question 21

Antibody Mediated Immunity

Answer 21

Antibody mediated immunity is performed by B cells

Bind antigen (either directly or on antigen presenting cells) & trigger response to it

Activated B cells multiply & turn into Plasma cells which make antibodies to the pathogen.

Question 22

Antibodies

Answer 22

Made by Plasma Cells (type of B-cell)

Each one recognises 1 specific antigen

B-cells = activated by presence of their particular antigen divide to make a clone (clonal selection)

B-cell clone secretes antibody specific to antigen

Antibodies have many different functions

Question 23

Opsonisation

Answer 23

Coat pathogen to make it easier for phagocytes to engulf it –

Question 24

agglutination

Answer 24

can be done by joining many antigens together into a big clump

Question 25

Neutralisation

Answer 25

Bind to & coat pathogen or toxins produced by pathogen to stop cell entry (very important for viruses)

Question 26

Complement Activation

Answer 26

Antibodies combine with plasma component called “complement” may also kill bacteria directly by punching a hole (similar to NK cell perforin)