Organs of Touch - Skin

Skin is a thin, durable tissue that covers the entire body and provides protection and impermeability. It is very thin in some places, such as on the eyelids (0.5 mm thick), and thicker on the palms and soles (up to 5 mm). The skin consists of three layers: epidermis, dermis and subcutaneous fat.

The epidermis is the outer covering. It is formed by the superficial stratum corneum, consisting of dry cells that turn into a solid substance - keratin. The deeper layer - the germinal (Malpighian) layer - is formed by cells that constantly multiply and replace the cells of the stratum corneum.

The dermis also consists of two layers - the papillary layer, rich in blood vessels and nerves, and the reticular layer, which contains the sebaceous glands that produce sebum, and tactile receptors of nerve endings - the corpuscles of Vater-Pacini, Ruffini, Meissner and Krause, which allow you to feel heat , cold, pressure, shape, movement and other external stimuli. These nerve endings are more numerous in certain parts of the skin, such as the tip of the tongue and the pads of the fingers, making these parts more sensitive.

Subcutaneous fat is the deepest layer of the skin. This is a kind of “cushion” of adipose tissue that protects the body from cold and shock and accumulates the body’s energy reserve. It contains sweat glands that secrete sweat, and numerous hair sacs, each of which grows one hair.

There are about three million sweat glands in the skin. If placed in a row, they form a continuous line 48 km long.

The total daily growth of hair on your head is 2500 cm. The hair is so strong that it can stretch one third of its length without bursting. The braid, woven from 500 hairs, can withstand the weight of an adult.