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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).
Typically mammalian skin consists of collagen fibers arranged in a felt-work pattern, with no preferential fiber orientation. [12] However, the structures of skin in bats, birds, and gliding lizards are very different from those of typical mammalian skin. The structural arrangement of the fibers within bat wing skin enables the bat to act like ...
Some adaptations required to adjust to non-aquatic life include the movement and use of alternating limbs, the use of pelvic appendages as sturdy propulsors, and the use of a solid surface at the organism's base to generate propulsive force required for walking. [4]
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]
Amniotes are distinguished from the other living tetrapod clade — the non-amniote lissamphibians (frogs/toads, salamanders/newts and caecilians) — by the development of three extraembryonic membranes (amnion for embryonic protection, chorion for gas exchange, and allantois for metabolic waste disposal or storage), thicker and keratinized ...
Human skin shows higher variation in colour than any other single mammalian species and is the result of natural selection. Skin pigmentation in humans evolved to primarily regulate the amount of ultraviolet radiation (UVR) penetrating the skin, controlling its biochemical effects. [20]
Pterosaurian pycnofibrils strongly resemble mammalian hair, but are thought to have evolved independently. [70] Ornithischian (bird-hipped) dinosaurs had a pelvis shape similar to that of birds, or avian dinosaurs, which evolved from saurischian (lizard-hipped) dinosaurs. [71] The Heterodontosauridae evolved a tibiotarsus which is also found in ...
Elaine V. Fuchs is an American cell biologist known for her work on the biology and molecular mechanisms of mammalian skin and skin diseases, who helped lead the modernization of dermatology. Fuchs pioneered reverse genetics approaches, which assess protein function first and then assess its role in development and disease.