Diseases and Immunity - IGCSE Biology - Core

Defense Mechanisms of the Body

Mechanical Barriers

-Nose hair

-Skin

Chemical Barriers

-Mucus

-Stomach Acid

Cells

-Phagocytosis

-Antibody production (by lymphocytes)

Antibody Production

-Specific antigen binds to specific receptor

-Antigen - receptor binding activates the lymphocyte to produce antibodies (which are pretty much the same shape as the receptors but "loose" versions))

-Antibodies attach onto their respective pathogen antigens

Phagocytosis

-Phagocytosis is a cellular process for ingesting and eliminating particles larger than 0.5 μm in diameter, including microorganisms, foreign substances, and apoptotic cells. Phagocytosis is found in many types of cells and it is, in consequence an essential process for tissue homeostasis.

Controlling the spread of disease

-Personal hygiene/ Washing hands

- To prevent direct/ Indirect transmission of diseases

-Sewage

-Can contaminate drinking water

-Waste disposal

-Waste that is not properly managed can attract rats, flies and other creatures which in turn, can spread disease