The only "living" portion of the hair is found in the follicle. Hair growth begins inside the hair follicle. The glands at the opening of the hair produce a fatty secretion that lubricates the hair. There are roughly two million small, tubular glands and sweat glands that produce watery fluids that cool the body by evaporation. The diameter of human hair varies from 0.017 to 0.18 millimeters (0.00067 to 0.00709 in). Its complex structure slides as the hair swells and is covered with a single molecular layer of lipid that makes the hair repel water. Oval and other shaped fibers are generally more wavy or curly. People with straight hair have round hair fibers. The shape of the follicle determines the shape of the cortex, and the shape of the fiber is related to how straight or curly the hair is. The cortex contains melanin, which colors the fiber based on the number, distribution and types of melanin granules. The highly structural and organized cortex, or second of three layers of the hair, is the primary source of mechanical strength and water uptake. The innermost region, the medulla, is an open and unstructured region which is not always present. the medulla, a disorganized and open area at the fiber's center Įach strand of hair is made up of the medulla, cortex, and cuticle.the cortex, which contains the keratin bundles in cell structures that remain roughly rod-like.the cuticle, which consists of several layers of flat, thin cells laid out overlapping one another as roof shingles.Hair fibers have a structure consisting of several layers, starting from the outside: A cross section of the hair shaft may be divided roughly into three zones.
Hair type chart skin#
the hair shaft, which is the hard filamentous part that extends above the skin surface.This organ is located in the dermis and maintains stem cells, which not only re-grow the hair after it falls out, but also are recruited to regrow skin after a wound. the part beneath the skin, called the hair follicle, or, when pulled from the skin, the bulb or root.The word "hair" usually refers to two distinct structures:
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