Defence against pathogens

Question 1

What are the 6 primary defences of an animal?

Answer 1

Skin
Mucous membranes
Wound repair
blood clotting
inflammation
expulsive reflexes

Question 2

How does inflammation defend against pathogens?

Answer 2

Mast cells activated by damaged tissue secrete histamines and cytokines.
Histamines dilate vessels, increasing blood flow = increased heat which reduces ability of pathogen to reproduce. Also increases permeability of blood vessels so plasma leaves creating tissue fluid which causes swelling.
Cytokines - attract white blood cells = phagocytosis

Question 3

What are the two types of defence that plants use against pathogens?

Answer 3

Physical and chemical

Question 4

What are plants 3 physical defences?

Answer 4

waxy cuticle
cell walls
Callose

Question 5

What is Callose and how does it protect plants?

Answer 5

It’s a polysaccharide and it’s released into the spaces between cell walls, plasmodesmata, phloem and plasma membranes in times of stress. This makes it harder for pathogens to enter the cells. (blocks off the area trapping the pathogen)

Question 6

What are plants chemical defences?

Answer 6

They produce toxic chemicals. Alkaloids and tannins. Alkaloids - bitter tasting and have poisonous characteristics. Tannins - bitter taste and bind to proteins in gut making it hard to digest

Question 7

Describe the blood clotting cascade?

Answer 7

platelets activated by damaged tissue (coming into contact with collagen)
They secrete thromboplastin and serotonin (clotting factors)
Thromboplastin - catalyses prothrombin into thrombin, thrombin catalyses fibrinogen in blood plasma into insoluble fibrin
The fibrin attaches to platelets causing the clot.
Serotonin - vasoconstriction to reduce blood flow to area