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 5. 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 skin is composed of two major layers: a superficial epidermis and a deeper dermis.
The epidermis consists of several layers beginning with the innermost deepest stratum basale germinatum , followed by the stratum spinosum, stratum granulosum, stratum lucidum when present , and ending with the outermost layer, the stratum corneum. The topmost layer, the stratum corneum, consists of dead cells that shed periodically and is progressively replaced by cells formed from the basal layer.
The stratum basale also contains melanocytes, cells that produce melanin, the pigment primarily responsible for giving skin its color. Melanin is transferred to keratinocytes in the stratum spinosum to protect cells from UV rays. The dermis connects the epidermis to the hypodermis, and provides strength and elasticity due to the presence of collagen and elastin fibers.
It has only two layers: the papillary layer with papillae that extend into the epidermis and the lower, reticular layer composed of loose connective tissue. The hypodermis, deep to the dermis of skin, is the connective tissue that connects the dermis to underlying structures; it also harbors adipose tissue for fat storage and protection.
The skin consists of two layers and a closely associated layer. The epidermis provides protection, the dermis provides support and flexibility, and the hypodermis fat layer provides insulation and padding. They appear to be sloughing off. What determines the color of skin, and what is the process that darkens skin when it is exposed to UV light?
Cells of the epidermis derive from stem cells of the stratum basale. Describe how the cells change as they become integrated into the different layers of the epidermis. Skip to content Learning Objectives By the end of this section, you will be able to: Describe the layers of the skin and the functions of each layer Identify the components of the integumentary system Describe the layers of the skin and the functions of each layer Describe the layers of the epidermis and dermis Identify and describe the hypodermis and fascia Describe the role of keratinocytes and their life cycle Describe the role of melanocytes in skin pigmentation.
External Website View this animation to learn more about layers of the skin. Figure 5. Everyday Connection — Lipid Storage The hypodermis is home to most of the fat that concerns people when they are trying to keep their weight under control.
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. Chapter Review The skin is composed of two major layers: a superficial epidermis and a deeper dermis. Interactive Link Questions The skin consists of two layers and a closely associated layer.
Review Questions. Hair and nails are both examples, i. The hair follicles are associated with sebaceous oil glands and arrector pili smooth muscle. This muscle is responsible for goose bumps appearing on the skin in response to cold. The epidermis also gives rise to eccrine sweat glands, a tangle of tubules deep within the dermis that secrete a watery salt solution into a duct that ends on the skin surface.
Larger apocrine sweat glands are found in the armpits and groin. Different areas of the body have different proportions of the adnexal and hair follicle structures present. For example:. Melanocytes are found in the basal layer of the epidermis. These cells produce a pigment called melanin , which is responsible for different skin colour. Melanin is packaged into small parcels or melanosomes , which are then transferred to keratinocytes. Langerhans cells break the allergen into smaller pieces then migrate from the epidermis into the dermis.
They find their way to lymphatics and blood vessels before eventually reaching the lymph nodes. Here they present the allergen to immune cells called lymphocytes. Merkel cells are cells found in the basal layer of the epidermis. Their exact role and function are not well understood. Special immunohistochemical stains are needed to visualise Merkel cells.
The dermis is the fibrous connective tissue or supportive layer of the skin. The major fibres are:. The collagen and elastin fibres are bound together by ground substance , a mucopolysaccharide gel in which the nutrients and wastes can diffuse to and from other tissue components.
The stratum corneum is sloughed off continually as new cells take its place, but this shedding process slows down with age. Complete cell turnover occurs every 28 to 30 days in young adults, while the same process takes 45 to 50 days in elderly adults. The dermis is located beneath the epidermis and is the thickest of the three layers of the skin 1. The main functions of the dermis are to regulate temperature and to supply the epidermis with nutrient -saturated blood.
Much of the body's water supply is stored within the dermis. This layer contains most of the skins' specialized cells and structures, including:.
The upper, papillary layer, contains a thin arrangement of collagen fibers. The papillary layer supplies nutrients to select layers of the epidermis and regulates temperature. Both of these functions are accomplished with a thin, extensive vascular system that operates similarly to other vascular systems in the body.
Constriction and expansion control the amount of blood that flows through the skin and dictate whether body heat is dispelled when the skin is hot or conserved when it is cold. The epidermis is the outermost layer of our skin. It is the layer we see with our eyes. It contains no blood supply of its own—which is why you can shave your skin and not cause any bleeding despite losing many cells in the process.
The epidermis is itself divided into at least four separate parts. A fifth part is present in some areas of our body. In order from the deepest layer of the epidermis to the most superficial, these layers strata are the:. Skin overview : Skin layers, of both hairy and hairless skin.
Human skin: This image details the parts of the integumentary system. The stratum basale, also called the stratum germinativum, is the basal base layer of the epidermis. This layer is one of the most important layers of our skin. This is because it contains the only cells of the epidermis that can divide via the process of mitosis, which means that skin cells germinate here, hence the word germinativum. In this layer, the most numerous cells of the epidermis, called keratinocytes, arise thanks to mitosis.
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