3.2 Factors Affecting the Immune System

 A vaccine is a special version of an antigen that gives you immunity against a disease (like a weakened form of a disease)  Started by people like Mary Montagu noticing women in Turkey infecting their children with a mild form of small pox or doctors like Edward Jenner noticing that farmers who had cow pox never got small pox

1. Allergies  Unusually high sensitivity to some substance which acts like an antigen  Substances that cause allergic reactions are called allergens  Symptoms include runny nose and watery eyes which are a side effect of a substance called histamines  Antihistamines are taken to combat the effect  If the reaction is severe and a person goes into anaphylactic shock then needles with adrenaline are injected into the body

2. Acquired immunodeficiency syndrome (AIDS)  Caused by the HIV virus which attacks and destroys helper T cells so other pathogens can enter the body  Mainly transmitted in body fluid (semen and blood)

 Eat a well balanced diet  Maintain your personal hygiene  Keep your home clean  Avoid tobacco and other non-prescription drugs  Get plenty of rest and exercise  Keep your vaccinations up to date  Do not engage in activities that involve sharing body fluids with others