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The skin weighs an average of four kilograms, covers an area of two square metres, and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. [1] The two main types of human skin are: glabrous skin, the hairless skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. [3]
Some skin secretions are associated with body hair. Skin secretions originate from glands that in dermal layer of the epidermis. Sweat, a physiological aid to body temperature regulation, is secreted by eccrine glands. Sebaceous glands secrete the skin lubricant sebum. Sebum is secreted onto the hair shaft and it prevents the hair from splitting.
All of the organs that rise from the ectoderm such as the nervous system, teeth, hair and many exocrine glands, originate from two adjacent tissue layers: the epithelium and the mesenchyme. [8] Several signals mediate the organogenesis of the ectoderm such as: FGF , TGFβ , Wnt , and regulators from the hedgehog family .
The actual skin colour of different humans is affected by many substances, although the single most important substance determining human skin colour is the pigment melanin. Melanin is produced within the skin in cells called melanocytes and it is the main determinant of the skin colour of darker-skinned humans.
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 dermis is composed of three major types of cells: [3] fibroblasts, macrophages, and mast cells.. Apart from these cells, the dermis is also composed of matrix components such as collagen (which provides strength), elastin (which provides elasticity), and extrafibrillar matrix, an extracellular gel-like substance primarily composed of glycosaminoglycans (most notably hyaluronan ...
skin - dead superficial layer: Stratified squamous, keratinized - integumentary: sweat gland ducts: Stratified cuboidal - integumentary: mesothelium of body cavities: Simple squamous: mesothelium: reproductive - female: ovaries: Simple cuboidal: germinal epithelium (female) reproductive - female: fallopian tubes: Simple columnar, ciliated ...
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]