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What Is The Main Function Of Skin Cells
William Montagna, professor of dermatology, Oregon Health Sciences University, Portland. Author of The Structure and Function of the Skin.
Skin Health & Well Aging Part 1: Skin Function
F. John G. Ebling Professor of Zoology, 1968–82; Independent Researcher in Dermatology, University of Sheffield, England. Co-editor and contributor to Textbook of Dermatology.
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Human skin, in human anatomy, the covering or covering of the surface of the body that both provides protection and receives sensory stimuli from the external environment. The skin consists of three layers of tissue: the epidermis, the outermost layer, which contains the primary protective structure, the stratum corneum; the dermis, a fibrous layer that supports and strengthens the epidermis; and the subcutaneous tissue, a subcutaneous layer of fat below the dermis that supplies nutrients to the other two layers and that cushions and insulates the body.
The apparent lack of body hair immediately distinguishes humans from all other large land mammals. Regardless of individual or racial differences, the human body appears more or less hairless, in the sense that hair is so residual as to appear absent; however, hair grows profusely in certain areas. These relatively hairy areas can be referred to as epigamic areas and they deal with social and sexual communication, either visually or through scent from glands associated with the hair follicles.
Skin Functions Of Skin
The characteristics of the skin change from birth to old age. In babies and children, it is velvety, dry, soft and largely free of wrinkles and spots. Children under two years of age sweat poorly and irregularly; their sebaceous glands function minimally. During adolescence, hair becomes longer, thicker and more pigmented, especially on the scalp, axillae, pubis and the male face. General skin pigmentation increases, localized pigment foci appear mysteriously, and acne lesions often develop. Hair growth, sweating and sebaceous secretion begin to blossom. As we age, anatomical and physiological changes, as well as exposure to sunlight and wind, leave skin, especially unprotected by clothing, dry, wrinkled and sagging.
Human skin, more than that of any other mammal, exhibits striking topographical differences. An example of this is the difference between the palms and the backs of the hands and fingers. The skin of the eyebrows is thick, rough and hairy; that of the eyelids is thin, smooth, and covered with almost invisible hairs. The face is rarely visibly hairy on the forehead and cheekbones. It is completely hairless in the red border of the lips, but coarsely pubescent on the chin and jaws of males. The surfaces of the forehead, cheeks and nose are usually oily, in contrast to the relatively fat-free lower surface of the chin and jaws. The skin of the chest, pubic region, scalp, axillae, abdomen, soles of the feet, and ends of the toes varies as structurally and functionally as it would if the skin in these different regions belonged to different animals.
Leather achieves strength and flexibility by being composed of multiple layers oriented so that each complements the others structurally and functionally. To enable communication with the environment, innumerable nerves—some modified as specialized receptor end-organs, others more or less structureless—approach as close as possible to the surface layer, and nearly every skin organ is sheathed by skeins of fine sensory nerves.
The dermis makes up most of the skin and provides physical protection. It consists of a combination of fibers, mainly collagen, with materials known as glycosaminoglycans, which are capable of retaining a large amount of water, thus maintaining the firmness of the skin. A network of stretchy elastic fibers keeps the skin taut and restores it after stretching.
Structure Of The Skin
Hair follicles and skin glands arise from the epidermis but are deeply embedded in the dermis. The dermis is richly supplied with blood vessels, although none penetrate the living epidermis. The epidermis receives materials only by diffusion from below. The dermis also contains nerves and sensory organs at various levels.
Human skin is extremely well supplied with blood vessels; it is pierced by a tangled though apparently ordered mass of arteries, veins, and capillaries. Such a blood supply, far in excess of the maximum biological needs of the skin itself, is evidence that the skin is at the service of the circulatory vascular system, functioning as a cooling device. To aid this function, sweat glands pour water onto its surface, the evaporation of which absorbs heat from the skin. If the environment is cold and body heat must be conserved, skin blood vessels constrict in rapid, consistent rhythms, allowing only a small amount of blood to flow through them. When the environment is warm, they contract at long intervals, ensuring a free flow of blood. During muscular exertion, when large amounts of generated heat must be dissipated, blood flow through the skin is maximal.
In addition to controlling body temperature, the skin also plays a role in regulating blood pressure. Much of the blood flow can be controlled by opening and closing certain sphincter vessels in the skin. These vessels allow blood to circulate through the peripheral capillary beds or bypass them by being directed directly from the small arteries to the veins.
Human skin is permeated by a complex network of lymphatic vessels. In the more superficial parts of the dermis, small lymphatic vessels that appear to end in blind sacs function as tributaries to a superficial lymphatic network, which in turn opens into vessels that become progressively larger in the deeper parts of the dermis. The deeper, larger vessels are embedded in the loose connective tissue that surrounds the veins. The walls of the lymphatic vessels are so relaxed and contracted that they are often not visible in specimens prepared for microscopic examination. However, their abundance has been demonstrated by injecting vital dyes into the dermis and observing the clearance of the dye.
Fibroblast Structure Function Human Skin Cell Stock Vector (royalty Free) 249538903
Because lymphatic vessels have little or no muscle in their walls, lymph circulation is slow and largely controlled by such external forces as pressure, skeletal muscle action, massage, and heat. Any external pressure, even from a fixed bandage, for example, interferes with its progress. Since the skin plays a major role in the body’s immunological responses, its lymphatic drainage is as important as its circulatory system.
The intact surface of the skin is cut by the openings of the sweat glands and hair follicles – the so-called pores – and is scored by intersecting lines that outline characteristic patterns. All individuals have approximately the same markings on any part of the body, but the details are unique. The lines are oriented in the general direction of the elastic stress. Countless of them, deep and shallow, together with the pores, give each part of the body a characteristic topography. Like the deeper furrows and ridges on the palms and soles, skin lines are mostly established before birth. The fine details of each part of the body surface are specific to each individual. Fingerprints are used as a means of personal identification because they have high relief, more obvious patterns, and can be easily obtained.
Some of the lines on the surface of the skin are acquired after birth as a result of use or damage. For example, furrows on the forehead are an accentuation of already existing congenital wrinkles that become more pronounced in old age. As the skin becomes less firm as we age, it also forms wrinkles. Some occupations leave marks on the skin which, depending on the duration and severity, can be transient or permanent.
The palms of the hands and feet are engraved by various alternating ridges and furrows, which together constitute dermatoglyphics. The ridges follow variable courses, but their arrangement in certain areas has a consistent structural plan. Although apparently continuous, the ridges have many breaks and bumps, branching and varying in length. Every little area of the surface has edge details that do not match anywhere in the same individual or in any other individual, even an identical twin. This unmistakable signature makes dermatoglyphs the best-known physical feature for personal identification. Before + During + After Hair Facts + Skin 4 FAQs Horror-mones Hair Removal Methods Links + Resources History of Electrolysis Beware of Laser Hair Removal
The Power Of Marine Phospholipids For Skin Care
Keep your skin healthy. It is the largest organ of our body and healthy skin reflects overall health. The skin has six main functions that help maintain its homeostasis.
The Malpighian layer produces the pigmentation of the skin and protects it from the harmful effects of ultraviolet radiation. Darker skin provides greater protection against the effects of sun exposure, most notably skin cancer
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