Immune System

Question 1

Non-Specific Defence Mechanism (1st Lines of Defences)

Answer 1

• Skin - ‘Intact skin’ - Prevents entry of ‘pathogens, and barrier of tough tightly packed cells
• Mucous membrane - ‘Traps, removes and destroys pathogens’

Question 2

Non-Specific Defence Mechanism (2nd Lines of Defences)

Answer 2

• Inflammation - Damaged cells release chemical eg. histamine which cause ‘vasodilation’ that increase the ‘permeability’ of the vessel
• Phagocytes - Ingest and destroy all microbes, pathogens and abnormal that pass into the tissues.
• Fever - High body temperature produced as a response to a bacterial infection as high temp can destroy micro-organisms.

Question 3

Specific Defence Mechanism (3rd Lines of Defence)

Answer 3

• Directed only against specific foreign body that stimulated it - it is specific as ‘antibodies’ are produced to fight infection.
• Generated by an Antigen (foreign molecule) that trigger an immune response.
• Cell Mediated Immunity (T cells) - Regulate Immune response, T cells detect infected viral cells and tumour (Cytotoxic T cell) and kill them.
• Humoral Immunity (B cells) - Involves antibodies produced by B cells and antibody locks onto specific antigen (pathogen)
• Antibodies are produced in response to antigens and B and T cells produce memory cells