Skin

The skin is a major organ of the body forming 8% of its total mass
and having an area between 1.1-2.2m2. It is the major interface between the
body and the environment and covers the entire surface. It is continuous with
mucosae at the various orifices and with lining tissue of organs like eyes and
ears

Various structures including sebaceous glands, sweat glands, hair
follicles and nails are formed by modifications of epidermis. Sebaceous glands
secrete an oily substance called sebum and open on the sides of the hair
follicles. Sweat glands are of two types, Merocrine and Apocrine. Merocrine
glands are found throughout the body opening on the surface and secreting a
clear watery fluid. Apocrine glands are found in the regions like axilla, areola,
pubis, scrotum and perianal regions. Their ducts may open on the surface or
into the hair follicle.

Dermis is made up of connective tissue consisting of matrix in which is
embedded elastic and collagen fibres to give strength and elasticity. It also
provides a compartment for blood vessels, lymphatics, nerves and cells
associated with immunity. Receptors for the sensations such as touch, pain,
pressure, warmth, cold and vibration senses are also found in the skin.
Circulation through the skin serves two major functions nutrition and
conduction of heat to the environment.

Functions of skin

1. Skin forms an effective barrier against infection by microbes.
2. It prevents dehydration and provides defense against chemical, osmotic,
thermal and photic damage.
3. It limits and regulates heat loss.
4. It provides a major sensory surface with a range of receptors.
5. It has limited excretory and absorptive functions.
6. Skin also helps in the formation of vitamin D.
7. Its keratinization and high friction coefficient gives the skin a
characteristic texture and helps in movement and handling of various
substances.

Skin

Functions of skin

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