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sebum. Sebum helps in maintaining hair condition but also waterproofs the skin and prevents
it from cracking. Sebum also acts as a bactericidal and fungicidal agent.

Epidermis

Contains no blood vessels or nerve endings and its outer surface is essentially dead cells,
which are constantly being rubbed off and replaced.

The epidermis plays an important role in protecting the organs of the body including the
dermis. The epidermis allows liquids (sweat) to pass outwards through sweat glands in order
to cool the body. The inner layers of the epidermis also generate melanin, a pigment that is
darkened by sunlight, providing some protection from ultraviolet light.

Target Organs

A target organ is part of the body, e.g. lungs, brain, kidneys, liver, skin, which sustains an
adverse effect when it is exposed to, or is contaminated by, a particular harmful agent.
Harmful agents include:

chemical agents, e.g. dusts, fumes, gases, mists, vapours and liquids; and
biological agents, e.g. fungi, bacteria and viruses.

Harmful agents can cause both local and systemic effects

ENSIGN| Unit IG2 – Element 7 – Chemical and Biological 11
Agents