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| Hair Follicles Hair follicles are tiny tubular chambers of the skin in which hair takes its root and from which it extends up through the epidermal layers. Each follicle aids in supplying its respective hair with blood via a vein, an artery, and a papilla at the bulblike base of the follicle. The follicle itself is based in the subcutaneous layer, beneath the dermis. By excreting oil, follicles act to move dead skin cells to the surface of the skin. For this reason, sebaceous (oil) glands, muscles, and nerves accompany every follicle. Sebaceous Glands Sebaceous oil-secreting glands are found in all types of skin, all over the body, and usually with a follicle. These glands, which resemble tree branches, are made up of a tube and one or two small sacs that are actually groups of smaller pockets called alveoli. They occur alongside the hair follicle as tiny teardrop appendages. Sebaceous glands excrete oil that is produced when cells in the alveoli die and break apart. Their function is to lubricate hair and to facilitate sweating in the follicle. They do, however, occur in thin, hairless skin, like that of the inside or the mouth, where they aid in the regeneration of cells. Sweat Glands Sweat is a watery substance that is made up of urea (waste product of protein change in the kidneys), fatty acids, and salt. Perspiration is an important function of the skin that cools the body through evaporation and clears the body of waste that can be expelled through its pores. In order to manage such a critical task, the body employs a system of sweat glands that runs throughout the skin. A sweat gland is an elongated tubular structure that originates in the subcutaneous tissue beneath the dermis and extends up to the surface of the epidermis, where it ends at either a pore or a hair follicle. At its secretory base, the gland is coiled and bunched, but its emerging duct straightens as it reaches toward the surface. A sweat gland is one of two types, eccrine or apocrine. Eccrine sweat glands, of which there are a greater number than apocrine glands in the body, terminate in a pore. Therefore, eccrine glands are predominantly responsible for sweat secretion and cooling the body. They are found everywhere on the body except the rim of the lips and most of the penis. There may be as many as 2,000,000 to 5,000,000 eccrine glands in the body, with the greatest accumulation on the palms. Apocrine sweat glands open into and feed hair follicles explicitly. They are typically larger than eccrine glands and are more developed in women. They are found in greatest number in the pubic region and in the armpit. When an apocrine gland secretes sweat, some of its cells disintegrate. The product of this disintegration contributes to sweat, which, depending on the amount and type of bacteria it produces, carries an odor that is characteristic of perspiration. Skin Pigmentation Pigmentation of the skin, eyes, and hair is determined by the presence of melanin in cells of the epidermis called melanocytes. Varying amounts of melanin determine color in both skin type and body part. In addition to coloring the skin and eyes, melanin actually protects the eyes from excessive harmful UV rays. Melanin absorbs high-energy light, like UV and blue light, more than it does other light in the spectrum. This helps protect the lens as well as the retina, by dispersing light throughout the eye according to its intensity. Overexposure to UV rays causes tanning and burning |
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| Hair The structure of the hair is similar to that of the outer layer of skin. Just as the epidermis is formed by the cells in its deepest layer, reproducing and pushing the cells which become horny in character, so a hair is developed by pushing a group of cells at its base, pushing upward and in the process becoming keratinized. The part of the hair that is visible is the shaft, whereas that which is embedded in the dermis is the root. The root, together with its covering, forms the hair follicle. At the bottom of the hair follicle is a loop of capillaries enclosed in a connective tissue covering called the hair papilla. The cluster of epithelial cells lying over the papilla are the ones that reproduced and eventually form the hair shaft. As long as these cells remain alive, hair will regenerate even though it will be cut or plucked or otherwise removed. Each hair is kept soft and pliable by two or more sebaceous glands that secrete varying amounts of oily sebum into the follicle near the surface of the skin. Attached to the follicle, too, are small bundles known as arrector pile muscles. These muscles are of interest because when they contract, the hair "stands on end," as it does in extreme fright or cold. This mechanism also produces "gooseflesh." Goosepimples is the raised skin produced by hair in upright position. Hair color is due to different amounts of melanin pigments in the outer layer or cortex of the hair. White hair contains little or no melanin. The hair around the eyes and in the nose functions as a protective mechanism to keep out dust and foreign matter. hairshaft http://www.infusium.com/hair101/solutions.asp |
SKIN AND HAIR FOLLICLE ANATOMY AND GROWTH Much of the anatomical knowledge necessary for the performance of electrolysis is known to you. Further details are easily acquired from our diagrams and text. (For those who will be purchasing the book, more extensive descriptions are available in the reference guide - R21). A PLUCKED HAIR - THE HAIR SHAFT BULB The word "bulb" refers to the expansion or enlargement of the end of anything that is long and circulate or round, (e.g. a flower bulb or light bulb). When a hair is plucked from the hair follicle, the bottom end of the hair shaft demonstrates an enlargement or expansion known as the hair shaft bulb. Many writers use the term "hair bulb" without specifying whether they are describing the hair follicle bulb or the hair shaft bulb. In day to day electrolysis, unless otherwise specified, "bulb" virtually always refers to the hair shaft bulb. For clarity, we do not use the word bulb in this text without the preceding appropriate adjective. Further confusion is created by the imprecise use of the term "hair root". When you epilate a hair, get in the habit of referring to the bottom end of the hair as the hair shaft bulb, rather than as the hair TELOGEN (RESTING) HAIR SHAFT BULBS AND CLUB HAIRS Telogen (resting) hair shaft bulbs are observed in telogen hairs. These resting hairs may be easily found by running your fingers through your scalp, as everyone loses about 50 to 150 resting hairs per day. The bulb end is swollen and looks like a cotton applicator tip. It is called a club hair, because early writers that that telogen resting hair shaft bulbs looked like a club. The telogen hair shaft bulb is white. The telogen hair shaft bulb (club hair bulb) consists of shrunken hair matrix cells that have stopped growing. ANAGEN (GROWING) HAIR SHAFT BULBS Anagen hairs are growing, so to observe the hair shaft bulb you must forcibly pluck hair from the scalp (or other area). The hair shaft bulb is usually pigmented (black or dark) and the adjacent hair shaft may have a white coating composed of the root sheaths. Sometimes the sheaths are completely intact, whereas in other instances they may be patchy, and some of the hair shaft may be seen between the fragments of root sheaths. The anagen hair bulb consists of hair matrix cells and varying degrees of root sheaths. OTHER HAIR SHAFT BULBS A dystrophic or damaged hair shaft bulb is an anagen bulb that has been distorted by previous plucking or other damage. The sheaths may be absent and therefore the normal architecture is distorted. A variety of hair diseases, such as alopecia areata or treatments such as chemotherapy for cancer produce hair shaft bulbs which lack sheaths and normal anatomy. Their appearance is often tapered or frayed. Catagen is the brief stage between growth (anagen) and rest (telogen), and about one to two percent of hairs demonstrate a catagen hair shaft bulb. Its appearance is intermediate between the anagen and telogen hair shaft bulb. The hair root may be broken off during the plucking stage, and you may not always identify the hair shaft bulb. |
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