Hair follicle
The hair follicle is a dynamic organ found in mammalian skin.[1] It resides in the dermal layer of the skin and is made up of 20 different cell types, cheap canada goose uk each canada goose clearance sale with distinct functions. The hair follicle regulates Canada Goose Jackets hair growth via a complex interaction between hormones, neuropeptides and immune cells.[1] This complex interaction induces the hair follicle to produce different types of hair as seen on different parts of the body. For example, terminal hairs grow on the cheap Canada Goose scalp and lanugo hairs are seen covering the bodies of fetuses in utero and in canada goose coats on sale some canada goose new born babies.[1] The process of hair growth occurs in Canada Goose sale distinct sequential stages. The first stage is called anagen and is the active growth phase, catagen is the resting stage, telogen is the regression of the hair follicle phase, exogen is the active shedding of hair phase and lastly kenogen is the phase between the empty hair follicle and uk canada goose outlet the growth of new hair.[1]
The function of hair in humans has long been canadian goose jacket a subject of interest and continues to be an important topic in society, developmental biology and medicine. Of all mammals, humans https://www.canadagooseonlineshop.co.uk have the longest growth phase of scalp hair compared to hair growth on other parts of the body.[1] For centuries, humans have canada goose clearance ascribed esthetics to scalp hair styling and dressing and it is often used to communicate social or cultural norms in societies. In addition to its role in defining human, scalp hair also provides protection from UV sun rays and is an insulator against extremes of hot and cold temperatures.[1] Differences in the shape of the scalp hair follicle determine the observed buy canada goose jacket cheap ethnic Canada Goose online differences in scalp hair, length and texture.
There are many human diseases in which abnormalities in hair, texture or growth are early signs of local disease of the hair follicle or systemic illness. Well known diseases of the hair follicle include alopecia or hair loss, hirsutism or excess hair growth and lupus erythematosus.[2]
The position Canada Goose Online and distribution of hair canada goose sale outlet follicles changes over the body. For example, canada goose black friday sale the buy canada goose jacket skin of the palms and soles do not have hair follicles whereas skin of the scalp, forearms, legs and genitalia have abundant hair follicles.[1] There are many structures that make up the hair follicle. canada goose uk outlet Anatomically, the triad of hair follicle, sebaceous gland and arrector pili muscle Canada Goose Coats On Sale make up the pilosebaceous unit.[1]
A hair follicle consists of papilla is a large structure at the base of the hair follicle.[3] The papilla is made up mainly of connective tissue and a capillary loop. Cell Canada Goose Outlet division in the papilla is either rare or non existent[contradictory].
Around the papilla canada goose coats is the hair matrix.
A root canada goose uk shop sheath composed of an external and internal root sheath. The external root sheath appears empty with uk canada goose cuboid cells when stained with H stain. The internal root sheath is composed of three layers, Henle’s layer, Canada Goose Parka Huxley’s layer, and an internal cuticle that is continuous with the outermost layer of the hair fiber.
The bulge is located in the outer root sheath at the insertion point of the arrector pili muscle. canada goose store It houses several types of stem cells, which supply the entire hair follicle with new cells, and take part in healing the epidermis after a wound.[4][5] Stem cells express the marker LGR5+ in vivo.[6]
Other structures associated with the hair follicle include the cup in which the follicle grows known as the infundibulum,[7] the arrector pili muscles, the sebaceous glands, and the apocrine sweat glands. receptors sense the position of the hair.
Attached to the follicle is a tiny bundle of muscle fiber called the arrector pili. This muscle is responsible for causing the follicle lissis to become more perpendicular to the surface of the skin, and causing the follicle to protrude slightly above the surrounding skin (piloerection) and a pore encased with skin oil. This process results in goose bumps (or goose flesh).
Also attached to the follicle is a sebaceous gland, which produces the oily or waxy substance sebum. canada goose uk black friday The differences in and texture of hair are due to many factors: the position of the hair bulb relative to the hair follicle, size and shape of the dermal papilla, and the curvature of the hair follicle.[1] The scalp hair follicles in Caucasians is in shape canada goose factory sale and therefore produces or wavy hair. Whereas, the scalp hair follicle of African people descent is more curvy resulting in the growth of tightly curled hair.[1].