Page 13 - LECTURE NOTES

2.3 Learning Objective

At the end of reading this module the learner will be able to

1. Identify common skin diseases

2. Define each skin
3. Explain the etiologic agents and clinical manifestations of each disease

4. List the various diagnostic measures, in the diagnosis of common skin diseases
5. Manage cases presenting with skin diseases

6. Describe the epidemiology, control, and prevention of common skin diseases

2.4. Structures and functions of the skin

The skin is the largest organ in our body. It comprises about 15% of the body weight.

It is composed of three layers: epidermis, dermis, and subcutaneous tissue (fat). The
epidermis, the outer most layer is directly contiguous with the environment. It is

formed by an ordered arrangement of cells called keratinocytes, the basic function of
which is to synthesize keratin, a filamentous protein that serves a protective function.

The dermis is the middle layer, composed of collagen, tough and resilient part of the
skin lies on the subcutaneous tissue which is principally composed of lobules of fat

cells.

All skin is made up of these three layers. Although there is a considerable regional

variation in their relative thickness: the epidermis is thickest on the palms and soles
and very thin on the eyelids. The dermis is thickest on the back. The amount of fat is

generous on the abdomen and buttock compared with the nose and sternum.

Cells of the epidermis

Keratinocyte - produces keratin which forms the outer most skin layer covered by thin
lipids to give the skin protective capacity from water and heat loss, penetration of

microbial agents, and other trauma by physical mechanisms.

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