KA5 Non-specific body defences

Question 1

What is a pathogen?

Answer 1

A pathogen is a bacterium, virus or other micro organisms that causes disease

Question 2

What are epithelial cells?

Answer 2

Closely packed epithelial cells are found in the skin and inner linings of the digestive and respiratory systems.
They provide a physical barrier which is the first line of defence against infection

Question 3

What are the chemical secretions produced against invading pathogens?

Answer 3

Tears, saliva, mucus and stomach acid

Question 4

What chemical is released from mast cells?

Answer 4

Histamine

Question 5

What are the two effects that histamine has on the body?

Answer 5

Vasodilation- blood vessels dilate which increases blood flow
Increased capillary permeability

Question 6

What are the two benefits of increased blood flow and permeability of capillary walls?

Answer 6

An accumulation of phagocytes and clotting elements at the site of infection

Question 7

What does phagocytes do?

Answer 7

Phagocytes recognise pathogens and destroy them by phagocytosis

Question 8

What is phagocytosis?

Answer 8

Phagocytosis involves the engulfing of pathogens and their destruction by digestive enzymes contained in lysosomes

Question 9

What does phagocytes release to attract other immune cells?

Answer 9

Cytokines

Question 10

What are cytokines?

Answer 10

Cytokines are protein molecules that act as a signal to specific white blood cells causing them to accumulate at the site of infection