Physiology of Skin

The skin comprises three layers: epidermis, dermis and the hypodermis. Skin forms the major link between man and the environment. The skin is the Human body’s LARGEST ORGAN, covering an area of about 2 square meters or 22 square feet and weighs around 3.6 kilogram. It is the thickest on palms and soles of feet measuring about 1.5 mm thick and the thinnest on the eyelids and post auricular region measuring 0.05 mm thick. It consists of various layers and tissues each with important functions.

skin physiology

Functions of Skin

PROTECTION

SENSATION

THERMO-REGULATION

ABSORPTION

SECRETION

Protection:- skin is the only connecting link between the body and environment. It protects the body from injuries, skin has a tough structure and fatty layer beneath which protects underlying important structures.

Skin also protects the body against infection; Langerhans cells which are tissue resident dendritic cells of the skin, function as macrophages and engulf foreign particles, damaged cells and bacterias.

Ultraviolet rays present in the environment have the tendency to produce deeper damage to the tissues of the skin but Melanocyte cells present in the epidermis produce a protective skin darkening pigment known as Melanin.

Melanin absorbs the UV rays and neutralizes the radicles of the harmful rays.

Sensation:- temperature changes and sensation of touch, pressure are felt through nerve endings present in the dermis. This function prevents burn injury but deeper injuries and burns affect the nerve endings which also affects the sensation function.

Thermal regulation:- body temperature through skin is regulated by the blood supply by the process of vasodilation and vasoconstriction. In vasodilation the blood vessels dilate and heat is released along with blood supply, by this body temperature is reduced. In vasoconstriction the blood vessels are constricted and heat is retained.

Through sweat glands heat is reduced by sweat.

Absorption:- skin absorption is transport of substance be it medication, cosmetics from the outside of the skin into the skin and also into the blood supply. This function gets affected by burns , injuries and skin diseases.

Excretion:- sweat glands in the skin secrete out sweat with sweat water, salt and urea a product of catabolism is also excreted. Sweat helps in releasing the heat and keeping the body cool.

 

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