Health and disease

• Pathogens are microorganisms that can cause disease, such as bacteria, viruses, fungi, protists. Communicable diseases are caused by the spread of pathogens.
• Non-communicable disease such as cardiovascular disease - caused by build up of fatty deposits or high blood pressure and can lead to heart attacks.
• Physical barriers such as skin, nose hairs, cillia. Chemical barriers such as stomach acid are primary lines of defence in the body, the immune system is the secondary.
• The immune system contains two types of WBC: phagocytes (break down pathogens) and lymphocytes (recognise antigens to create antibodies). Memory lymphocytes remember these antigens.
• Antibiotics cure bacterial disease by killing bacteria cells. Vaccines cure viruses, that contain inactive pathogens to create antibodies.