Examples of hair follicle in the following topics:
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- The root is part of the
hair enclosed by the hair follicle, which is itself a tube-like involution of
the skin.
- An oval hair shaft is responsible
for wavy hair.
- In the deepest portion of
the each hair follicle lies the hair bulb.
- Depending on the kind of
hair and location, hair can have one of several purposes:
- Attached to a hair follicle is a bundle of
muscle fibers.
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- Chemotherapy causes hair loss by killing cells that divide rapidly, one of the main properties of most cancer cells and hair follicles.
- Chemotherapy also harms cells that divide rapidly under normal circumstances, such as cells in the bone marrow, mouth, nail beds, and hair follicles.
- The hair of the scalp is most noticeably affected, but chemotherapy also causes the loss of the hair of the eyelashes, eyebrows, and the rest of the body.
- Some chemotherapeutic agents cause dramatic hair loss and baldness, while other medications may only cause hair to thin .
- Sometimes, a patient's hair will grow back differently.
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- Male baldness is the result of genetic sensitivity of hair follicles to dihydrotestosterone that causes hair follicles to atrophy.
- Male pattern baldness is caused by a genetic sensitivity of hair follicles to dihydrotestosterone (DHT).
- In genetically-prone scalps, i.e. those experiencing male or female pattern baldness, DHT initiates a process of follicular miniaturization in which the hair follicle begins to deteriorate.
- In time, hair becomes thinner and its overall volume is reduced, resembling fragile vellus hair or "peach fuzz" until, finally, the follicle falls dormant and ceases producing hair completely.
- Recent research suggests that elevated levels of the enzyme prostaglandin D2 synthase and its product prostaglandin D2 (PGD2) in hair follicles contribute to androgenetic alopecia.
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- Sebum acts to protect and waterproof hair and skin, and keep them from becoming dry, brittle, and cracked.
- Sebum is the cause of some people experiencing "oily" hair if it is not washed for several days.
- Sebaceous glands can usually be found in hair-covered areas where they are connected to hair follicles to deposit sebum on the hairs, and bring it to the skin surface along the hair shaft.
- The structure consisting of hair, hair follicle, and sebaceous gland is also known as pilosebaceous unit.
- Sebum is the cause of some people's experiencing "oily" hair, as in hot weather or if not washed for several days.
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- Acne, clinically known as acne vulgaris, is a common human skin disease affecting skin with the densest population of sebaceous follicles such as the face, upper parts of the chest, and back .
- Acne develops as a result of blockages in hair follicles.
- Bacteria becomes trapped in these clogged follicles, producing pus and inflammation as the immune system attempts to destroy the bacteria.
- The sebaceous gland produces oily secretions that can block the follicle, resulting in a pimple.
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- Alopecia usually affects the hair of the scalp, but can also cause the loss of hair from the eyebrows, eyelashes, and body.
- Alopecia areata is thought to be an autoimmune disorder in which the body attacks its own hair follicles and suppresses or stops hair growth.
- Exclamation point hairs are often present in alopecia.
- Exclamation point hairs are hairs that become narrower along the length of the strand closer to the base, producing a characteristic "exclamation point" appearance and weak point in the hair shaft.
- Different skin areas can exhibit hair loss and regrowth at the same time.
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- The hair cells in the cochlea are the most
sensitive mechanoreceptors, transducing air pressure waves into nerve
signals sent to the brain.
- Hair follicle receptors are located in hair follicles and sense position changes of hair strands.
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- Hair removal, also known as epilation or depilation, is the removal of body hair, and describes the methods used to achieve that result.
- Although nearly all human skin is covered with hair follicles, it appears hairless.
- Hair removal, also known as epilation or depilation, is the removal of body hair, and describes the methods used to achieve that result.
- Depilation is the removal of the part of the hair above the surface of the skin.
- Hair is also sometimes removed by plucking with tweezers.
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- The hairs on the skin lie flat and prevent heat from being trapped by the layer of still air between the hairs.
- When these muscles relax their attached hair follicles are not erect.
- In addition, our body thermoregulates
using our hair.
- The arrector pili muscles contract (piloerection) and lift the hair follicles upright.
- This makes the hairs stand on end, which acts as an insulating layer, trapping heat.
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- Follicle development signals the beginning of the menstrual cycle.
- At the start of the menstrual cycle, some 12-20 primary follicles begin to develop under the influence of elevated levels of follicle stimulating hormone (FSH) to form secondary follicles.
- The primary follicles have formed from primordial follicles, which developed in the ovary as a fetus at around 10–30 weeks after conception and are arrested in the prophase state of the cellular cycle.
- The remaining follicle is called the dominant follicle and is responsible for producing large amounts of estrogen during the late follicular phase.
- This causes the secondary follicle to develop into a tertiary follicle, which then leaves the ovary 24–36 hours later.