Sweat glands Sweat glands have the form of tubes with excretory ducts that secrete sweat. It has 98-99% of water, 0.5% - NaCl, and the rest -

Sweat and sebaceous glands, nails, hair and skin

Sweat glands

Sweat glands have the form of tubes with excretory ducts that secrete sweat. It has 98-99% of water, 0.5% — NaCl, and the rest — the metabolism products, in particular urea. Most of the sweat glands are in the armpit area, on the palms and soles. Sweat is odorless. Unpleasant smell is either in unhealthy human (especially with diseases of the lungs, kidneys), or those who do not adhere to the rules of personal hygiene.

Sebaceous glands

The holes of the sebaceous glands open into the hair follicle; their secret — is the fats that are distributed evenly over the scalp surface of the skin, protecting it from water penetration and microorganisms into the body. In addition, fat prevents excessive evaporation of water from the body. Many of the sebaceous glands are in the skin of the face, but they are not associated with hair follicles there.

Hair

Hair — is a filiform epithelial skin derivative (diagram 94.). They cover almost the entire surface of the body except the lips, hands, soles. The amount of hair on the body is different. For example, the head has about 100-150 thousand. Hair color depends on the concentration of melanin pigment. Approximately in 45-50 years old, the number of hair on the head, eyebrows and eyelashes decreases and starts their graying caused by a gradual decrease in melanin and filling hair with microscopic air bubbles. The normal rate of hair growth on the head — is a centimeter per month (hair grow is better in the warmer months), and the life of hair period — 4-5 years. On the average, each day falls 30-50 hairs from a human head. Their growth is regulated by the nervous and endocrine systems. Hair has such parts: rod that protrudes above the surface of the skin, and the root, located in the dermis. Taken from http://worldofschool.org

Diagram 94. The structure of the skin and hair: 1 — epidermis; 2 — dermis; 3 — subcutaneous fat; 4 — the root of the hair; 5 — hair bulb; 6 — artery; 7 — vein; 8 — sweat gland; 9 — the hair shaft; 10 — nociceptors; 11 — sebaceous gland; 12 — the muscle that raises the hair; 13 — collagen fiber; 14 — mechanoreceptor; 15 — fiber sensory nerves; 16 — fiber vegetative nerves

Hair root

The root of the hair is placed in the hair follicle. Here opens the sebaceous gland duct; with the exception of facial hair: there sebaceous glands have their own ducts. Smooth muscle fibers of the dermis are also attached to the hair follicle; they raise the hair. Below the root expands. Hair growth is due to the division of its cells. At the bottom of the hair in follicle enters the papilla — formation of a conical shape. A lot of nerve fibers come to him, as well as small artery that branches into a dense capillary net; a hair is well supplied with blood and fed. If a person lives a healthy life, he has a thick, beautiful hair. With poor nutrition, systematic use of alcohol hair become thin, dull, easy to ruffle, fall down.

Hair rod

The rod or the actual hair is composed of medulla, covered with thick cuticle. Medulla — are a horny cells that contain dense protein — keratin and melanin and air bubbles. Cuticle — is a single flat layer of enucleated cells that adjacent to each other roof-tile-alike.

Nails

Nails — are horny plates at fingertips. They have the body covered with nail plate, the root and the nail fold. Their growth rate is 0.1 mm per day. Normally, nails are smooth and shiny, transparent and pink.

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Questions:
  • Explain the biological significance of epidermis horny layer delamination.