Where the fat is deposited and accumulates within the hypodermis depends on hormones testosterone, estrogen, insulin, glucagon, leptin, and others , as well as genetic factors. Fat distribution changes as our bodies mature and age.
Men tend to accumulate fat in different areas neck, arms, lower back, and abdomen than do women breasts, hips, thighs, and buttocks. The body mass index BMI is often used as a measure of fat, although this measure is, in fact, derived from a mathematical formula that compares body weight mass to height.
Therefore, its accuracy as a health indicator can be called into question in individuals who are extremely physically fit. In many animals, there is a pattern of storing excess calories as fat to be used in times when food is not readily available. In much of the developed world, insufficient exercise coupled with the ready availability and consumption of high-calorie foods have resulted in unwanted accumulations of adipose tissue in many people. Although periodic accumulation of excess fat may have provided an evolutionary advantage to our ancestors, who experienced unpredictable bouts of famine, it is now becoming chronic and considered a major health threat.
Not only is this a problem for the individuals affected, but it also has a severe impact on our healthcare system. Changes in lifestyle, specifically in diet and exercise, are the best ways to control body fat accumulation, especially when it reaches levels that increase the risk of heart disease and diabetes.
The color of skin is influenced by a number of pigments, including melanin, carotene, and hemoglobin. Recall that melanin is produced by cells called melanocytes, which are found scattered throughout the stratum basale of the epidermis. The melanin is transferred into the keratinocytes via a cellular vesicle called a melanosome Figure. Melanin occurs in two primary forms. Eumelanin exists as black and brown, whereas pheomelanin provides a red color.
Dark-skinned individuals produce more melanin than those with pale skin. Exposure to the UV rays of the sun or a tanning salon causes melanin to be manufactured and built up in keratinocytes, as sun exposure stimulates keratinocytes to secrete chemicals that stimulate melanocytes.
The accumulation of melanin in keratinocytes results in the darkening of the skin, or a tan. This increased melanin accumulation protects the DNA of epidermal cells from UV ray damage and the breakdown of folic acid, a nutrient necessary for our health and well-being.
In contrast, too much melanin can interfere with the production of vitamin D, an important nutrient involved in calcium absorption. Thus, the amount of melanin present in our skin is dependent on a balance between available sunlight and folic acid destruction, and protection from UV radiation and vitamin D production. It requires about 10 days after initial sun exposure for melanin synthesis to peak, which is why pale-skinned individuals tend to suffer sunburns of the epidermis initially.
Dark-skinned individuals can also get sunburns, but are more protected than are pale-skinned individuals. Melanosomes are temporary structures that are eventually destroyed by fusion with lysosomes; this fact, along with melanin-filled keratinocytes in the stratum corneum sloughing off, makes tanning impermanent.
Too much sun exposure can eventually lead to wrinkling due to the destruction of the cellular structure of the skin, and in severe cases, can cause sufficient DNA damage to result in skin cancer. When there is an irregular accumulation of melanocytes in the skin, freckles appear. Moles are larger masses of melanocytes, and although most are benign, they should be monitored for changes that might indicate the presence of cancer Figure.
Disorders of the… Integumentary System The first thing a clinician sees is the skin, and so the examination of the skin should be part of any thorough physical examination. Most skin disorders are relatively benign, but a few, including melanomas, can be fatal if untreated. A couple of the more noticeable disorders, albinism and vitiligo, affect the appearance of the skin and its accessory organs. Although neither is fatal, it would be hard to claim that they are benign, at least to the individuals so afflicted.
Albinism is a genetic disorder that affects completely or partially the coloring of skin, hair, and eyes. The defect is primarily due to the inability of melanocytes to produce melanin.
Individuals with albinism tend to appear white or very pale due to the lack of melanin in their skin and hair. Recall that melanin helps protect the skin from the harmful effects of UV radiation. Individuals with albinism tend to need more protection from UV radiation, as they are more prone to sunburns and skin cancer.
They also tend to be more sensitive to light and have vision problems due to the lack of pigmentation on the retinal wall.
Treatment of this disorder usually involves addressing the symptoms, such as limiting UV light exposure to the skin and eyes. In vitiligo , the melanocytes in certain areas lose their ability to produce melanin, possibly due to an autoimmune reaction.
This leads to a loss of color in patches Figure. Neither albinism nor vitiligo directly affects the lifespan of an individual. Other changes in the appearance of skin coloration can be indicative of diseases associated with other body systems. Tumors of the pituitary gland can result in the secretion of large amounts of melanocyte-stimulating hormone MSH , which results in a darkening of the skin. A sudden drop in oxygenation can affect skin color, causing the skin to initially turn ashen white.
This happens when the oxygen supply is restricted, as when someone is experiencing difficulty in breathing because of asthma or a heart attack. This ABC video follows the story of a pair of fraternal African-American twins, one of whom is albino. Watch this video to learn about the challenges these children and their family face. Which ethnicities do you think are exempt from the possibility of albinism? The subcutaneous fat layer is the deepest layer of skin.
It consists of a network of collagen and fat cells. It helps conserve the body's heat and protects the body from injury by acting as a shock absorber. The epidermis is the thin outer layer of the skin. It consists of 3 types of cells: Squamous cells. The dermis is the middle layer of the skin. Alternatively, when it is hot, more blood is allowed into the superficial plexus, and the skin flushes. The blood in the superficial capillaries is cooled by the evaporation of sweat of the surface of skin.
Skin functions and Layers Some facts about skin Skin is the largest organ of the body. It has an area of 2 square metres 22 square feet in adults, and weighs about 5 kilograms. The thickness of skin varies from 0. Skin is the major barrier between the inside and outside of your body! Functions of skin Protection : it protects against UV light, mechanical, thermal and chemical stresses, dehydration and invasion by micro-organisms.
Sensation : skin has receptors that sense touch, pressure, pain and temperature. Thermoregulation : various features of the skin are involved in regulating temperature of the body. For example sweat glands, hair, and adipose tissue. Metabolic functions : subcutaneous adipose tissue is involved in production of vitamin D, and triglycerides.
Find out more about hair. The Dermis and Hypodermis The dermis is a connective tissue layer, that contains collagen and elastin fibres, and fibroblasts, macrophages and adipocytes, as well as nerves, glands and hair follicles. The sweat glands are found deep in this region and in the hypodermis. Can you see the two regions of the dermis in the picture above? The skin also contains receptors for other steroid hormones oestrogens, progestogens and glucocorticoids and for vitamin A. How an individual is perceived by others is important.
People make judgements based on what they see and may form their first impression of someone based on how that person looks. Throughout history, people have been judged because of their skin, for example, due to its colour or the presence of a skin condition or scarring. Skin conditions are visible — in this skin-, beauty- and image-conscious society, the way patients are accepted by other people is an important consideration for nurses.
This article gives an overview of the structure and functions of the skin. Part 2 will provide an overview of the accessory structures of the skin and their functions. Tagged with: Newly qualified nurses: systems of life. Sign in or Register a new account to join the discussion. You are here: Dermatology. Skin 1: the structure and functions of the skin. This article has been double-blind peer reviewed Scroll down to read the article or download a print-friendly PDF here if the PDF fails to fully download please try again using a different browser Assess your knowledge and gain CPD evidence by taking the Nursing Times Self-assessment test Read part 2 of this series here.
Biga LM et al Anatomy and Physiology. The integumentary system 5. Cork MJ The importance of skin barrier function. Edinburgh: Churchill Livingstone. London: Mosby. Holden C et al Advised best practice for the use of emollients in eczema and other dry skin conditions. Journal of Dermatological Treatment ; 3, Hughes E Skin: its structure, function and related pathology. Hunter J et al Clinical Dermatology. Oxford: Blackwell Science.
Kolarsick PAJ et al Anatomy and physiology of the skin. Dermatology Nursing ; 2, White R, Butcher M The structure and functions of the skin. Aberdeen: Wounds UK.
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