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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 .
Cells in the epidermis contain a structural matrix of keratin, which makes this outermost layer of the skin almost waterproof, and along with collagen and elastin gives skin its strength. Rubbing and pressure cause thickening of the outer, cornified layer of the epidermis and form protective calluses, which are useful for athletes and on the ...
An example is the skin on the forearm, which is on average 1.3 mm in males and 1.26 mm in females. [4] One average square inch (6.5 cm 2) of skin holds 650 sweat glands, 20 blood vessels, 60,000 melanocytes, and more than 1,000 nerve endings. [5] [better source needed] The average human skin cell is about 30 μm in
It forms the outermost layer of the skin and the inner lining of the mouth, esophagus and vagina. [2] In the epidermis of skin in mammals, reptiles, and birds, the layer of keratin in the outer layer of the stratified squamous epithelial surface is named the stratum corneum. Stratum corneum is made up of squamous cells which are keratinized and ...
The skin is one of the largest organs of the body. In humans, it accounts for about 12 to 15 percent of total body weight and covers 1.5 to 2 m 2 of surface area. [1] 3D still showing human integumentary system. The skin (integument) is a composite organ, made up of at least two major layers of tissue: the epidermis and the dermis. [2]
The cells in the stratum granulosum do not divide, but instead form skin cells called keratinocytes from the granules of keratin. These skin cells finally become the cornified layer ( stratum corneum ), the outermost epidermal layer, where the cells become flattened sacks with their nuclei located at one end of the cell.
Keratinization begins in the stratum spinosum, [5] although the actual keratinocytes begin in the stratum basale. [4] They have large pale-staining nuclei as they are active in synthesizing fibrillar proteins, known as cytokeratin, which build up within the cells aggregating together forming tonofibrils. The tonofibrils go on to form the ...
The outermost layer of human skin is composed of dead stratified squamous, keratinized epithelial cells. [14] Tissues that line the inside of the mouth, the esophagus, the vagina, and part of the rectum are composed of nonkeratinized stratified squamous epithelium. Other surfaces that separate body cavities from the outside environment are ...