4.1 Diseases and the Immune System

Question 1

Cytokines

Answer 1

Cytokines attract phagocytes to the site of infection
They also stimulate the hypothalamus to increase body temperature

Question 2

Opsonin

Answer 2

Molecules which coat the pathogen so that phagocytes can easily bind to and phagocytose the pathogen

Question 3

Phagocytosis

Answer 3

A process where a cell binds to a pathogen it wants to engulf on the cell surface

1. Attraction: pathogens produce chemicals which attract phagocytes
2. Recognition: phagocytes recognise foreign proteins in the pathogen
3. Endocytosis: the phagocyte engulfs the pathogen
4. The bacteria are enclosed within a vacuole to form a phagosome
5. The phagosome combines with a lysosome to form a phagolysosme
6. Enzymes from the lysosome digest and destroy the pathogen

Question 4

Chemotaxis

Answer 4

Attraction phase of phagocytosis:
Pathogens produce chemicals which attract phagocytes

Question 5

Endocytosis

Answer 5

The phagocyte engulfs the pathogen

Question 6

Macrophage

Answer 6

Make up 4% of WBC’s
Involved in both specific and non specific immune system

Question 7

Neutrophil

Answer 7

Make up 70% of all WBC’s
Have multi-lobed nuclei so they can more easily migrate through tissue

Question 8

Phagosome

Answer 8

A vacuole which has enclosed the bacteria

Question 9

Phagolysosome

Answer 9

A phagosome combined with a lysosome

Question 10

Keratin

Answer 10

A fibrous protein forming structures like hair

Question 11

Sebum

Answer 11

An oily substance that protects and hydrated the skin’s surface
It mixes with lipids to form a protective coating on the skin

Question 12

Lysozyme

Answer 12

Contain enzymes that break down the cell wall of bacteria
Found in tears and urine

Question 13

Phagocyte

Answer 13

Engulf and destroy pathogens
In phagocytosis they recognise foreign proteins on the pathogen

Question 14

Histamine

Answer 14

Cause vasodilation which increases skin temperature. Means pathogens are less likely to reproduce

Make blood vessels leakier, forcing blood plasma and WBC’s out and into surrounding tissues

Question 15

Thromboplastin

Answer 15

An enzyme that triggers the clotting response

Question 16

Thrombin

Answer 16

catalyses the conversion of soluble plasma protein fibrinogen into an insoluble fibrous form called fibrin

Question 17

Fibrin

Answer 17

Fibrin fibres trap red blood cells, forming clots

Question 18

Fibrinogen

Answer 18

A protein produced in the liver which is changed into fibrin during the clotting of blood

Question 19

Serotonin

Answer 19

Causes smooth muscle in the blood vessel to constrict and narrow, reducing blood flow to the area (during blood clotting and wound repair)