Hair: Integumentary System

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Hair is considered one of the components of the integumentary system, along with the skin, nails, glands and nerves. Mammalian hair has many functions including protection from environmental factors and the ability to disperse sweat gland products such as pheromones. Almost every part of the human body is covered by hair except for the palms, hands and bottoms of the feet. On average, every person has about five million hairs; each of these hairs is born from a follicle or tiny tube-like structure that grows into the dermis layer of the skin. Oftentimes this follicle even reaches the subcutaneous layer, which is made of fat and connective tissue. (UXL Complete Health Research, 2001)
At the base of each hair follicle there are capillaries and …show more content…

The hair of the scalp is longer and more flexible, while the hair of the eyebrows tends to be short and stiff. Oval shaped hair shafts produce wavy hair, flat hair shafts create curly hair and hair shafts that are perfectly round create straight hair. There are also different types of melanin, a natural compound responsible for the production of color in the eyes, skin and hair. There is yellow, brown and black melanin, each produced by melanocytes located at the follicle base. With age, melanin production decreases, causing greying of hair. (Applegate & Saunders, 2001, pp …show more content…

This cycle tends to last anywhere from five to seven years and is shorter for hair on the eyebrows, armpits and pubic area. Inside the bulb of each hair is a component called the dermal papilla which controls the hair growth while the matrix of the hair, which contains a large amount of epidermal cells that rapidly divide, is responsible for the length of the hair. Next is the catagen phase which is characterized as a transition period between the anagen and telogen phases. At this time the hair bulbs are pushed out in order to become keratinized and the hair appears short and thick. This phase tends to only last between two and three weeks. During the telogen phase, no new cell division occurs, which means that the length of the hair remains the same. This pause allows the dermal papilla to fill up the matrix with new cells in preparation for the anagen phase to begin again. This phase can last between three and nine months. After this phase, the anagen phase begins again. The telogen phase is periodically followed by shedding, or exogen. This leads to the last phase, the exogen phase. This phase is characterized by the shedding of hair. Each day about one hundred hairs are shed from the average individual’s scalp. The shaft of the hair is shed and the follicle remains. Despite the fat that the exogen phase usually follows the telogen phase, there are exceptions when it does not, resulting in hair follicles needing to go

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