Non specific defence

Question 1

Epithelial cells

Answer 1

Epithelial cells form a physical barrier.

Closely-packed epithelial cells are found in the skin and inner linings of the digestive and respiratory systems.

Question 2

Chemical Secretions

Answer 2

Chemical secretions are produced against invading pathogens.

Secretions include tears, saliva, mucus and stomach acid.

Question 3

Pathogens

Answer 3

A pathogen is a bacterium, virus or other organism that can cause disease.

Question 4

The inflammatory response.

Answer 4

Histamine is released by mast cells causing vasodilation and increased capillary permeability. The increased blood flow leads to an accumulation of phagocytes and clotting elements at the site of infection.

Question 5

Phagocytosis

Answer 5

Phagocytes recognise pathogens and destroy them by phagocytosis
Phagocytosis involves the engulfing of pathogens and their destruction by digestive enzymes contained in lysosomes.

Question 6

Cytokines

Answer 6

Phagocytes release cytokines which attract more phagocytes to the site of infection.
Cytokines are protein molecules that act as a signal to specific white blood cells causing them to accumulate at the site of infection.