Burrhus Frederic Skinner, commonly known as B. F. Skinner, was an American psychologist, behaviorist, author, inventor, and social philosopher. He was the Edgar Pierce Professor of Psychology at Harvard University from 1958 until his retirement in 1974.
Skin is the soft outer tissue covering of vertebrates with three main functions: protection, regulation, and sensation.
Scabies, also known as the seven-year itch, is a contagious skin infestation by the mite Sarcoptes scabiei. The most common symptoms are severe itchiness and a pimple-like rash. Occasionally, tiny burrows may be seen in the skin. In a first-ever infection a person will usually develop symptoms in between two and six weeks. During a second infection symptoms may begin in as little as 24 hours. These symptoms can be present across most of the body or just certain areas such as the wrists, between fingers, or along the waistline. The head may be affected, but this is typically only in young children. The itch is often worse at night. Scratching may cause skin breakdown and an additional bacterial infection of the skin.
7-Dehydrocholesterol (7-DHC) is a zoosterol that functions in the serum as a cholesterol precursor, and is converted to vitamin D3 in the skin, therefore functioning as provitamin-D3. The presence of this compound in human skin enables humans to manufacture vitamin D3 (cholecalciferol) from ultraviolet rays in the sun light, via an intermediate isomer pre-vitamin D3. It is also found in the milk of several mammalian species. In insects it is a precursor for the hormone ecdysone, required for reaching adulthood. It was discovered by Nobel-laureate organic chemist Adolf Windaus.
Skin cancers are cancers that arise from the skin. They are due to the development of abnormal cells that have the ability to invade or spread to other parts of the body. There are three main types of skin cancers: basal-cell skin cancer (BCC), squamous-cell skin cancer (SCC) and melanoma. The first two, along with a number of less common skin cancers, are known as nonmelanoma skin cancer (NMSC). Basal-cell cancer grows slowly and can damage the tissue around it but is unlikely to spread to distant areas or result in death. It often appears as a painless raised area of skin, that may be shiny with small blood vessels running over it or may present as a raised area with an ulcer. Squamous-cell skin cancer is more likely to spread. It usually presents as a hard lump with a scaly top but may also form an ulcer. Melanomas are the most aggressive. Signs include a mole that has changed in size, shape, color, has irregular edges, has more than one color, is itchy or bleeds.
Vitiligo is a long-term skin condition characterized by patches of the skin losing their pigment. The patches of skin affected become white and usually have sharp margins. The hair from the skin may also become white. The inside of the mouth and nose may also be involved. Typically both sides of the body are affected. Often the patches begin on areas of skin that are exposed to the sun. It is more noticeable in people with dark skin. Vitiligo may result in psychological stress and those affected may be stigmatized.
Dermatology is the branch of medicine dealing with the skin, nails, hair and its diseases. It is a specialty with both medical and surgical aspects. A dermatologist is specialist doctor that manages diseases, in the widest sense, and some cosmetic problems of the skin, hair and nails.
Psoriasis is a long-lasting autoimmune disease characterized by patches of abnormal skin. These skin patches are typically red, dry, itchy, and scaly. On people with darker skin the patches may be purple in colour. Psoriasis varies in severity from small, localized patches to complete body coverage. Injury to the skin can trigger psoriatic skin changes at that spot, which is known as the Koebner phenomenon.
Skin effect is the tendency of an alternating electric current (AC) to become distributed within a conductor such that the current density is largest near the surface of the conductor, and decreases with greater depths in the conductor. The electric current flows mainly at the "skin" of the conductor, between the outer surface and a level called the skin depth. The skin effect causes the effective resistance of the conductor to increase at higher frequencies where the skin depth is smaller, thus reducing the effective cross-section of the conductor. The skin effect is due to opposing eddy currents induced by the changing magnetic field resulting from the alternating current. At 60 Hz in copper, the skin depth is about 8.5 mm. At high frequencies the skin depth becomes much smaller. Increased AC resistance due to the skin effect can be mitigated by using specially woven litz wire. Because the interior of a large conductor carries so little of the current, tubular conductors such as pipe can be used to save weight and cost.
The epidermis is the outermost of the three layers that make up the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water released from the body into the atmosphere through transepidermal water loss. The epidermis is composed of multiple layers of flattened cells that overlie a base layer composed of columnar cells arranged perpendicularly.
Sebaceous glands are microscopic exocrine glands in the skin that secrete an oily or waxy matter, called sebum, to lubricate and waterproof the skin and hair of mammals. In humans, they occur in the greatest number on the face and scalp, but also on all parts of the skin except the palms of the hands and soles of the feet. The type of secretion of the sebaceous glands is referred to as holocrine. In the eyelids, meibomian glands, also called tarsal glands, are a type of sebaceous gland that secrete a special type of sebum into tears. Fordyce spots are ectopic (misplaced) sebaceous glands found usually on the lips, gums and inner cheeks, and genitals. Areolar glands surround the female nipples.
Erythema is redness of the skin or mucous membranes, caused by hyperemia in superficial capillaries. It occurs with any skin injury, infection, or inflammation. Examples of erythema not associated with pathology include nervous blushes.
Behaviorism is a systematic approach to understanding the behavior of humans and other animals. It assumes that all behaviors are either reflexes produced by a response to certain stimuli in the environment, or a consequence of that individual's history, including especially reinforcement and punishment, together with the individual's current motivational state and controlling stimuli. Although behaviorists generally accept the important role of inheritance in determining behavior, they focus primarily on environmental factors.
Botflies, also known as warble flies, heel flies and gadflies, are a family of flies technically known as Oestridae. Their larvae are internal parasites of mammals, some species growing in the host's flesh and others within the gut. The Dermatobia hominis is the only species of botfly known to parasitize humans routinely, though other species of flies cause myiasis in humans.
Epidermolysis bullosa (EB) is a group of genetic conditions that result in easy blistering of the skin and mucous membranes. Blisters occur with minor trauma or friction and are painful. Its severity can range from mild to fatal. Those with mild cases may not develop symptoms until they start to crawl or walk. Complications may include esophageal narrowing, squamous cell skin cancer, and the need for amputations.
A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, hair, nails, and related muscle and glands. The major function of this system is as a barrier against the external environment.
A papule is a circumscribed, solid elevation of skin with no visible fluid, varying in area from a pinhead to 1 cm. It can be brown, purple, pink or red in color, and can cluster into a papular rash. Papules may open when scratched and become infected and crusty. Larger non-blisterform elevated lesions may be termed nodules.
ICD-10 is an international statistical classification used in health care and related industries.
Jack the Ripper is the best-known name for an unidentified serial killer generally believed to have been active in the largely impoverished areas in and around the Whitechapel district of London in 1888. In both the criminal case files and contemporary journalistic accounts, the killer was called the Whitechapel Murderer and Leather Apron.
The human skin is the outer covering of the body and is the largest organ of the integumentary system. The skin has up to seven layers of ectodermal tissue and guards the underlying muscles, bones, ligaments and internal organs. Human skin is similar to most of the other mammals skin, and human skin is very similar to pig skin. Though nearly all human skin is covered with hair follicles, it can appear hairless. There are two general types of skin, hairy and glabrous skin (hairless). The adjective cutaneous literally means "of the skin".
