The Body's Defences.

Question 1

Describe how lymphocytes react to ‘foreign’ material.

Answer 1

1) Produce antibodies.
2) L recognises antigen on surface of pathogen.
3) L divides + produces clones of itself
4) Some clones produce antibodies, which stick to surface antigens + destroy it by a) making pathogens stick together so Phagocytes can pick them up or b) act as label for P to recognise them or c) causing bacterial cells to burst or d)antitoxin, neutralise pathogenic toxins.
5) Some clones remain in blood (memory cells) + make people immune to particular pathogen.

Question 2

What is an antigen?

Answer 2

An antigen is a protein on the surface of a cell.

Question 3

What is an antibody?

Answer 3

A soluble protein that passes into the blood plasma, and bind to specific antigens.

Question 4

Difference between antibodies and antitoxins.

Answer 4

Antibody = protein produced by immune system in response to any pathogen. Can wither destroy, kill or inactivate pathogens.
Antitoxin = special type of antibody - render a toxic substance harmless.