Hairs arise from which layer of the skin

As with hair, nails form by keratinization. When the nail cells accumulate, the nail pushes forward. The skin below the nail is the matrix. The larger part of the nail, the nail plate , looks pink because of the network of tiny blood vessels in the underlying dermis.

The whitish crescent-shaped area at the base of the nail is the lunula pronounced: LOON-yuh-luh. Fingernails grow faster than toenails. Like hair, nails grow faster in summer than in winter. A nail that's torn off will regrow if the matrix isn't severely injured. Reviewed by: Larissa Hirsch, MD. Larger text size Large text size Regular text size. What Does Skin Do? Skin, our largest organ, has many jobs. It: protects the network of muscles, bones , nerves, blood vessels, and everything else inside our bodies forms a barrier that prevents harmful substances and germs from entering the body protects body tissues against injury helps control body temperature through sweating when we're hot and by helping keep heat in the body when we're cold Without the nerve cells in skin, people couldn't feel warmth, cold, or other sensations.

What Are the Parts of Skin? In these layers are three special types of cells: Melanocytes pronounced: meh-LAH-nuh-sites make melanin , the pigment that gives skin its color. All people have roughly the same number of melanocytes; the more melanin made, the darker the skin.

Exposure to sunlight increases the production of melanin, which is why people get suntanned or freckled. Keratinocytes pronounced: ker-uh-TIH-no-sites make keratin , a type of protein that's a basic component of hair, skin, and nails. Keratin in the skin's outer layer helps create a protective barrier. What Does Hair Do? The hair on our heads doesn't just look nice. Beneath the surface of the skin are nerves, nerve endings, glands, hair follicles, and blood vessels.

Sweat is produced by glands in the dermis and reaches the surface of the skin through tiny ducts. The epidermis is the relatively thin, tough, outer layer of the skin.

Most of the cells in the epidermis are keratinocytes. They originate from cells in the deepest layer of the epidermis called the basal layer. New keratinocytes slowly migrate up toward the surface of the epidermis. Once the keratinocytes reach the skin surface, they are gradually shed and are replaced by newer cells pushed up from below. The outermost portion of the epidermis, known as the stratum corneum, is relatively waterproof and, when undamaged, prevents most bacteria, viruses, and other foreign substances from entering the body.

The epidermis along with other layers of the skin also protects the internal organs, muscles, nerves, and blood vessels from injury. In certain areas of the body that require greater protection, such as the palms of the hands and the soles of the feet, the stratum corneum is much thicker. Scattered throughout the basal layer of the epidermis are cells called melanocytes, which produce the pigment melanin, one of the main contributors to skin color.

Melanin's primary function, however, is to filter out ultraviolet radiation from sunlight see Overview of Sunlight and Skin Damage Overview of Sunlight and Skin Damage Sunlight stimulates vitamin D production, helps control some chronic skin diseases such as psoriasis , and causes a sense of well-being.

However, sunlight can cause skin damage. Damage includes Skin cancer is most common among people who work or play sports outside and among sunbathers. Fair-skinned people are particularly susceptible The epidermis also contains Langerhans cells, which are part of the skin's immune system. Although these cells help detect foreign substances and defend the body against infection, they also play a role in the development of skin allergies.

The dermis, the skin's next layer, is a thick layer of fibrous and elastic tissue made mostly of collagen, with a small but important component of elastin that gives the skin its flexibility and strength. The dermis contains nerve endings, sweat glands and oil glands sebaceous glands , hair follicles, and blood vessels. The nerve endings sense pain, touch, pressure, and temperature. Some areas of the skin contain more nerve endings than others.

For example, the fingertips and toes contain many nerves and are extremely sensitive to touch. The sweat glands produce sweat in response to heat and stress. Sweat is composed of water, salt, and other chemicals. As sweat evaporates off the skin, it helps cool the body.

Specialized sweat glands in the armpits and the genital region apocrine sweat glands secrete a thick, oily sweat that produces a characteristic body odor when the sweat is digested by the skin bacteria in those areas. Offering protection for the fingertips, they facilitate grasping and tactile sensitivity in the finger. The fingertip has many nerve endings and receives information about objects we touch; the nail acts as a counterforce, providing even more sensory input.

The rate of nail growth varies from person to person: fingernails average between 0. The growth of nails is a complex process and, in humans, is genetically controlled to ensure the nail is flat; this is unlike the process in other animals and primates that have claws.

Nail growth can also be negatively affected by trauma and inflammation Graham-Brown and Bourke, Tagged with: Newly qualified nurses: systems of life. Sign in or Register a new account to join the discussion. You are here: Tissue viability.

Skin 2: accessory structures of the skin and their functions. Abstract Understanding the skin requires knowledge of its accessory structures. This article has been double-blind peer reviewed Scroll down to read the article or download a print-friendly PDF here if the PDF fails to fully download please try again using a different browser Read part 1 of this series here. London: Elsevier. London: Mosby Elsevier. Kolarsick PAJ et al Anatomy and physiology of the skin.

Weller RB et al Clinical Dermatology. Oxford: Blackwell Science. Related files. NT Contributor. Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions.

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