Suggested Readings :
(1) Advanced-level Biology for Hong Kong, Bk.2, by Y.K.Ho, Manhattan Press, pp. 88-101.
(2) Immunology, an outline for students of medicine and biology, by D.M. Weir, E.L.B.S., pp. 1 - 103.
(3) A-Level Biology, by Phillips and Chilton, Oxford Press pp. 141 - 149.
(4) Advanced Biology, Principles and applications, by C.J.Clegg with D.G. Mackean, International student edition, John Murray Press, pp. 368 - 375.
(5) Understanding Biology, for Advanced Level, 4th ed.,by Glenn and Susan Toole, Stanley Thornes Press, pp.626-646.

What is health

Health is a situation of the body in which the whole body is considered as good and normal functioning. Acording to the World Health Organization (WHO), health is defined as "a state of complete physical, social and mental well-being, and not merely the absence of disease or infirmity"

So, the health of a person is most concerned in the area of physical health and mentally health. In this syllabus, only the physical health is concerned.

The physical health of an individual describes the physical conditions of the body. It includes the completeness of body structures and effectiveness of the body functions. Damages in the completeness of the body structures or damages in the effectiveness of the body functions are considered as illness. The completeness of the body can be damaged by physical means, chemical means and biological means. The damages in the effectiveness of body functions can be the result of physical injuries, chemical poisonings, invasion of external materials or over-reaction of the body (allergy).

The mental health describe the efficiency of normal reasoning abilities. If the person cannot think normally or efficiently, the person can be considered as mentally sick. Mental illness can be induced by damages in the physical body or inappropriate mental activities.