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The human skin is the outer covering of the body and is the largest organ of the integumentary system. The skin has up to seven layers of ectodermal tissue guarding muscles, bones, ligaments and internal organs. Human skin is similar to most of the other mammals' skin, and it is very similar to pig skin.
In humans, they constitute 90% of epidermal skin cells. [1] Basal cells in the basal layer (stratum basale) of the skin are sometimes referred to as basal keratinocytes. [2] Keratinocytes form a barrier against environmental damage by heat, UV radiation, water loss, pathogenic bacteria, fungi, parasites, and viruses.
The word skin originally only referred to dressed and tanned animal hide and the usual word for human skin was hide. Skin is a borrowing from Old Norse skinn "animal hide, fur", ultimately from the Proto-Indo-European root *sek-, meaning "to cut" (probably a reference to the fact that in those times animal hide was commonly cut off to be used as garment).
Merkel cells, also known as Merkel–Ranvier cells or tactile epithelial cells, are oval-shaped mechanoreceptors essential for light touch sensation and found in the skin of vertebrates. They are abundant in highly sensitive skin like that of the fingertips in humans , and make synaptic contacts with somatosensory afferent nerve fibers .
These stem cells develop into both keratinocyte precursors and melanoblasts - and these melanoblasts supply both hair and skin (moving into the basal layer of the epidermis). There is additionally evidence that melanocyte stem cells are present in cutaneous nerves, with nerve signals causing these cells to differentiate into melanocytes for the ...
Langerhans cell is represented by a yellow oval; blue arrows correspond to is_a relations, and orange arrows correspond to develops_from relations. Only a subset of Langerhans cell parent types are included in the figure. [1] A Langerhans cell (LC) is a tissue-resident macrophage of the skin [2] once thought to be a resident dendritic cell. [3]
The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. [1] The epidermal layer provides a barrier to infection from environmental pathogens [2] and regulates the amount of water released from the body into the atmosphere through transepidermal water loss.
The predominant cell keratinocyte, which produces keratin, a fibrous protein that aids in skin protection, is responsible for the formation of the epidermal water barrier by making and secreting lipids. [6] The majority of the skin on the human body is keratinized, with the exception of the lining of mucous membranes, such as the inside of the ...