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They can be identified by the fact that they express "hard", "trichocyte" or "hair" keratin proteins. [1] These are modified keratins containing large amounts of the amino acid cysteine , which facilitates chemical cross-linking of these proteins to form the tough material from which hair and nail is composed.
Denudation can involve the removal of both solid particles and dissolved material. These include sub-processes of cryofracture, insolation weathering, slaking, salt weathering, bioturbation, and anthropogenic impacts. [4] Factors affecting denudation include: Anthropogenic (human) activity, including agriculture, damming, mining, and ...
The hair follicle is an organ found in mammalian skin. [1] It resides in the dermal layer of the skin and is made up of 20 different cell types, each with distinct functions.. The hair follicle regulates hair growth via a complex interaction between hormones, neuropeptides, and immune cells
In mammalian outer hair cells, the varying receptor potential is converted to active vibrations of the cell body. This mechanical response to electrical signals is termed somatic electromotility; [13] it drives variations in the cell's length, synchronized to the incoming sound signal, and provides mechanical amplification by feedback to the traveling wave.
In colder conditions, the nature of sebum becomes more lipid, and in coating the hair and skin, rain is effectively repelled. [10] [11] Sebum is produced in a holocrine process, in which cells within the sebaceous gland rupture and disintegrate as they release the sebum and the cell remnants are secreted together with the sebum.
Damaged sweat and sebaceous glands, hair follicles, muscle cells, and nerves are seldom repaired. They are usually replaced by the fibrous tissue. The result is the formation of an inflexible, fibrous scar tissue. Human skin cells are capable of repairing UV-induced DNA damages by the process of nucleotide excision repair. [2]
Denudation coupled with peeling and cracking of skin gives rise to a "crazy pavement dermatosis" pattern seen in Kwashiorkor or Kwashiorkor-Marasmus complex. In occupational asthma , the denudation of the bronchial mucosa can occur in the setting of nonimmunologic exposures (i.e., chemical spill, chlorine, ammonia), causing irritation.
Multipotent adult stem cells have the capacity to be self-renewing and give rise to different cell types. Stem cells give rise to progenitor cells, which are cells that are not self-renewing, but can generate several types of cells. The extent of stem cell involvement in cutaneous (skin) wound healing is complex and not fully understood.