5.1 Defence Mechanisms

Question 1

What is the immune system?

Answer 1

A system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens.

Question 2

How does the immune system recognise its own cells?

Answer 2

~ each type of cell has specific molecules on its surface that identify it
~ The proteins in these molecules have a wide variety, and a highly specific tertiary structure
~ this variety of 3D specific structures , distinguishes one cell from another.
~ this protein molecules allow the immune system to identify pathogens , foreign cells, toxins and abnormal body cells

Question 3

How do lymphocytes destroy pathogens ( simple )

Answer 3

~specific lymphocytes already exist in the body - when a pathogen enters the body one of many lymphocytes will have a protein on its surface that is complementary to one of the proteins of the pathogen
~this lymphocyte is stimulated to divide to build up a ‘clonal section’ so it is effective when destroying the pathogen

Question 4

What is an antigen

Answer 4

Molecules (proteins) on the surface of body cells that can generate an immune response when detected by the body