The skin is very elastic, durable, and complex. It is the largest organ of the body. It is about 20 square feet of tissue that weighs about 6 to 7 pounds. On the eyelids, the skin is thin but on the soles of the feet it may be ½ inch thick.
The skin is frequently called "The mirror of the body". A healthy skin is usually a sign of good health. On the other hand, a serious illness often shows its presence on the surface of the skin. The study of the skin is known as dermatology and a dermatologist is a doctor who specializes in skin treatment.
Structure of the Skin
Skin is one of the largest organ which covers the entire surface of our body. The skin is made up of three main layers:
- Epidermis - Outer layer
- Dermis - Middle layer
- Subdermis – Innermost layer
Layers of the Skin
The outer layer of the skin is epidermis and inner layer is called dermis. There is a third layer which is made of fatty tissues called subdermis layer.
Epidermis consists almost entirely of dead and dying cells. It has almost no blood supply, except in the deepest layer. The epidermis is further divided into four distinct layers:
The cornified layer (Stratum Corneum): It is the surface layer of the skin. The cells of this layer contains a hard substance called keratin. This layer is very tough and nearly waterproof. The topmost cells are constantly being worn away and shed.
The clear layer (Stratum Lucidum): This consists of a thin layer of small cells through which light can pass.
The granuler layer (Stratum Granulosum): It contains dead cells. These cells look like granules and move towards the surface of the skin. They replace cells in the cornified layer that have been worn away.
The germinative layer (Stratum Germinativum): It is above the dermis. In this layer, new cells are continually being formed. Among these new cells can be found great numbers of special cells called melanocytes. These cells contain melanin, a brownish pigment that determines skin colour.
Dermis is a true skin made up of many interwoven fibres (not cells) of elastic proteins called collagen which give skin its ability to stretch. The dermis is divided into two layers:
The Papillary Layer: It has tiny finger like projections which help anchor the dermis to the epidermis. They are well supplied with blood vessels.
The Reticular Layer: This contains many structures like nerves, oil glands, sweat glands, hair follicles, blood vessels etc.
Functions of the Skin
The skin, like most organs, is vital to overall health and carries out many functions that help us to protect our health.
Temperature regulation: helps in regulating body temperature.
Protection: It protects the body from - heat, cold, bacteria, excess fluid and harmful elements in the environment.
Absorption: Skin is capable of absorbing necessary substance in a limited way e.g. topical medicine and cosmetics.
Sensation: It is the sensory organ for touch, heat, cold, pain etc. and transmits the information to brain.
Secretion: Skin is well supplied with sebaceous glands which secrete oil that is vital to our skin.
Execretion: Helps in execretion of toxic substances with sweat.