Structure of hair and skin.

Hair is a keratinized epidermal outgrowth found exclusively on the skin surface of mammals, composed of hard, cohesive keratin. It serves thermoregulatory and protective functions, and healthy hair can be an indicator of an organism's high biological quality.

The skin consists of several main layers. The uppermost layer is called the epidermis. Beneath it lies the dermis, and below that, the subcutaneous tissue. Each of these layers performs a specific function. The skin is the largest organ of the human body and is largely covered with hair.

Structure of the skin.

The epidermis is the outer layer that performs protective and regenerative functions and contains the pigment melanin, which gives color to the hair and skin. It is divided into four or five layers, depending on its thickness.

The dermis is the middle layer, composed primarily of fibrous connective tissue; it contains receptors, blood vessels, nerves, and glands—such as sweat glands—as well as hair roots. It is a nourishing and supportive layer ranging from 1 to 3 mm in thickness.

Beneath the skin lies the subcutaneous tissue, composed of loose connective tissue. It contains fat cells, the lower sections of hair roots, the secretory parts of glands, and certain receptors, and it provides insulation against sudden temperature changes.

Hair structure

A hair consists of the shaft, root, sheath, bulb, and papilla.

The primary component of hair is keratin. Hair pigment contains a coloring agent known as melanin—which gives hair its color—as well as fats and minerals.

Keratin is produced in the epidermis and is composed of, among other things, sulfur and nitrogen compounds. It protects the epidermis against harmful external factors. Melanin gives color to the hair and skin. There are two types of this pigment: granular and diffuse. Granular pigment gives hair a dark shade, while diffuse pigment results in a light shade. The more diffuse pigment present in the hair, the lighter the hair color.