Hair Wikipedia. Hair is a protein filament that grows from follicles found in the dermis, the innermost layer of the skin. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and fine vellus hair. Most common interest in hair is focused on hair growth, hair types and hair care, but hair is also an important biomaterial primarily composed of protein, notably alpha keratin. Attitudes towards different hair, such as hairstyles and hair removal, vary widely across different cultures and historical periods, but it is often used to indicate a persons personal beliefs or social position, such as their age, sex, or religion. OvervieweditThe word hair usually refers to two distinct structures the part beneath the skin, called the hair follicle, or, when pulled from the skin, the bulb. 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. A cross section of the hair shaft may be divided roughly into three zones. Hair fibers have a structure consisting of several layers, starting from the outside the cuticle, which consists of several layers of flat, thin cells laid out overlapping one another as roof shingles,the cortex, which contains the keratin bundles in cell structures that remain roughly rod like. DescriptioneditEach strand of hair is made up of the medulla, cortex, and cuticle. The innermost region, the medulla, is not always present and is an open, unstructured region. The highly structural and organized cortex, or middle layer of the hair, is the primary source of mechanical strength and water uptake. The cortex contains melanin, which colors the fiber based on the number, distribution and types of melanin granules. 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. Small Bald Patch In Hair' title='Small Bald Patch In Hair' />People with straight hair have round hair fibers. Oval and other shaped fibers are generally more wavy or curly. The cuticle is the outer covering. Its complex structure slides as the hair swells and is covered with a single molecular layer of lipid that makes the hair repel water. The diameter of human hair varies from 0. There are two million small, tubular glands and sweat glands that produce watery fluids that cool the body by evaporation. The glands at the opening of the hair produce a fatty secretion that lubricates the hair. Hair growth begins inside the hair follicle. The only living portion of the hair is found in the follicle. The hair that is visible is the hair shaft, which exhibits no biochemical activity and is considered dead. The base of a hairs root the bulb contains the cells that produce the hair shaft. Other structures of the hair follicle include the oil producing sebaceous gland which lubricates the hair and the arrector pili muscles, which are responsible for causing hairs to stand up. In humans with little body hair, the effect results in goose bumps. Root of the haireditThe root of the hair ends in an enlargement, the hair bulb, which is whiter in color and softer in texture than the shaft, and is lodged in a follicular involution of the epidermis called the hair follicle. Bulb of hair layers consist of fibrous connective tissue, glassy membrane, external root sheath, internal root sheath composed of epithelium stratum Henles layer and granular stratum Huxleys layer, cuticle, cortex and medulla of hair. Polaris Digital Wrench. Natural coloredit. A woman with dark blonde hair, the basal color appears brown due to higher levels of brownish eumelanin. All natural hair colors are the result of two types of hair pigments. Small Bald Patch In Hair' title='Small Bald Patch In Hair' />How to Help Your Hair Grow Faster when You Have a Bald Spot. Hair loss is a frustrating problem and it may seem like there is nothing you can do about it. Although. A young woman with alopecia hair loss tells what it was like coping with and finally accepting her bald patches. Photo Fritz CohenCorbis. Charlie Brown, with from left to right Schroeder, Lucy, and Patty. This image is from a 1952 comic strip. Appearance. Charlie Brown is drawn with only a small curl. IMG_0001-1.jpg' alt='Small Bald Patch In Hair' title='Small Bald Patch In Hair' />Both of these pigments are melanin types, produced inside the hair follicle and packed into granules found in the fibers. Eumelanin is the dominant pigment in brown hair and black hair, while pheomelanin is dominant in red hair. Blond hair is the result of having little pigmentation in the hair strand. Gray hair occurs when melanin production decreases or stops, while poliosis is hair and often the skin to which the hair is attached, typically in spots, that never possessed melanin at all in the first place, or ceased for natural genetic reasons, generally, in the first years of life. Human hair growtheditHair grows everywhere on the external body except for mucus membranes and glabrous skin, such as that found on the palms of the hands, soles of the feet, and lips. Hair follows a specific growth cycle with three distinct and concurrent phases anagen, catagen, and telogen phases. Each has specific characteristics that determine the length of the hair. All three occur simultaneously one strand of hair may be in the anagen phase, while another is in the telogen phase. The body has different types of hair, including vellus hair and androgenic hair, each with its own type of cellular construction. The different construction gives the hair unique characteristics, serving specific purposes, mainly, warmth and protection. TextureeditHair exists in a variety of textures. Three main aspects of hair texture are the curl pattern, volume, and consistency. The derivations of hair texture are not fully understood. All mammalian hair is composed of keratin, so the make up of hair follicles is not the source of varying hair patterns. There are a range of theories pertaining to the curl patterns of hair. Scientists have come to believe that the shape of the hair shaft has an effect on the curliness of the individuals hair. A very round shaft allows for fewer disulfide bonds to be present in the hair strand. This means the bonds present are directly in line with one another, resulting in straight hair. The flatter the hair shaft becomes, the curlier hair gets, because the shape allows more cysteines to become compacted together resulting in a bent shape that, with every additional disulfide bond, becomes curlier in form. As the hair follicle shape determines curl pattern, the hair follicle size determines thickness. While the circumference of the hair follicle expands, so does the thickness of the hair follicle. An individuals hair volume, as a result, can be thin, normal, or thick. The consistency of hair can almost always be grouped into three categories fine, medium, and coarse. This trait is determined by the hair follicle volume and the condition of the strand. Fine hair has the smallest circumference, coarse hair has the largest circumference, and medium hair is anywhere between the other two. Coarse hair has a more open cuticle than thin or medium hair causing it to be the most porous. Classification systemseditThere are various systems that people use to classify their curl patterns. Being knowledgeable of an individuals hair type is a good start to knowing how to take care of ones hair. There is not just one method to discovering ones hair type. Additionally it is possible, and quite normal to have more than one kind of hair type, for instance having a mixture of both type 3a 3b curls. Andre Walker system. This hair typing system is the most widely used system to classify hair. The system was created by the hairstylist of Oprah Winfrey, Andre Walker. According to this system there are four types of hair straight, wavy, curly, kinky.