Defence mechanisms

Defence mechanisms include:

• Skin
• Musus
• Ear wax
• Phagocytes - only attack pathogens
• Tears - chemical
• Stomach acid - chemical

Infection:

• An interaction between the pathogen and the body's various defence mechanisms

Immunity:

• The body's defences are better prepared for a second infection from the same pathogen and can kill it before it can cause any harm

Lymphocyte:

A type of white blood cell - takes two forms:

• Cell-mediated responses involving T lymphocytes
• Humoral responses involving B lymphocytes

Recognising your own cells:

• Lymphocytes must be able to distinguish between the body's own cells from those that are foreign
• Each type of cell has specific molecules on its surface to identify it
• The proteins on the surface are the most important because they have a large variety and high specific tertiary structure
• It is this variety of a specific 3-D structure that distinguishes one cell from another

It is usually the protein molecules that allow the immune system to identify -

• Pathogens - for example HIV
• Non-self material -…