Immunity

Yo yo yo. For those of you doing AQA AS Biology (2015 spec), here's the basics of what you need to know for the immunity chapter. This isn't covering antibodies, vaccinations or HIV - simply because that's info overload and it needs to be in digestable chunks for cramming. 

Defence Mechanisms

Non-Specific - response is immediate and the same for all pathogens

Physicial Barrier (e.g. skin)

Phagocytosis

Specific - response is slower and specific to each pathogen

Cell medidated response (T cells)

Humoral response (B cells)

Antigens

Any part of an organism or substance which is foreign (non self), and stimulates an immune response. 

They are usually proteins which usually are on the cell surface membranes of pathogens.

Antigens are not always on the invading cell. You can have antigen-presenting cells which are cells from the immune system which take the pathogen's antigens and allow the functions of the immune system to work. 

Lymphocytes 

Lymphocytes are white blood cells. Now you're in Y12 you need to remove 'white blood cell' from your vocabulary. Don't be like John. Don't say 'white blood cell' in your exam. 

There are two types of lymphocytes:

T lymphocytes (T cells)

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