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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 respiratory system develops from the lung bud, which appears in the ventral wall of the foregut about four weeks into development. The lung bud forms the trachea and two lateral growths known as the bronchial buds, which enlarge at the beginning of the fifth week to form the left and right main bronchi .
Mammal skin: (1) hair, (2) epidermis, (3) sebaceous gland, (4) Arrector pili muscle, (5) dermis, (6) hair follicle, (7) sweat gland. Not labelled, the bottom layer: hypodermis, showing round adipocytes. The integumentary system (skin) is made up of three layers: the outermost epidermis, the dermis and the hypodermis. The epidermis is typically ...
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).
The secretion of eccrine glands is a sterile, dilute electrolyte solution with primary components of bicarbonate, potassium, and sodium chloride (NaCl), [6] and other minor components that may include glucose, pyruvate, lactate, cytokines, immunoglobulins, antimicrobial peptides such as dermcidin, and many others.
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 final branch which is important for the digestive system is the inferior mesenteric artery, which supplies the regions of the digestive tract derived from the hindgut, which includes the distal 1/3 of the transverse colon, descending colon, sigmoid colon, rectum, and the anus above the pectinate line.
Firstly, the hydroxylation of a monophenol and secondly, the conversion of an o-diphenol to the corresponding o-quinone. o-Quinone undergoes several reactions to eventually form melanin. [5] Tyrosinase is a copper -containing enzyme present in plant and animal tissues that catalyzes the production of melanin and other pigments from tyrosine by ...