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Itchiness
Itch (also known as pruritus) is a sensation that causes the desire or reflex to scratch. Itch has resisted many attempts to be classified as any one type of sensory experience. Itch has many similarities to pain, and while both are unpleasant sensory experiences, their behavioral response patterns are different. Pain creates a withdrawal reflex, whereas itch leads to a scratch reflex. Unmyelinated nerve fibers for itch and pain both originate in the skin; however, information for them is conveyed centrally in two distinct systems that both use the same nerve bundle and spinothalamic tract. Classification Most commonly, an itch is felt in one place. If it is felt all over the body, then it is called ''generalized itch'' or ''generalized pruritus''. If the sensation of itching persists for six weeks or longer, then it is called ''chronic itch'' or ''chronic pruritus''. ''Chronic idiopathic pruritus'' or ''essential pruritus'' is a rare form of itch that persists for longer tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scratch Reflex
The scratch reflex is a response to activation of sensory neurons whose peripheral terminals are located on the surface of the body.Stein, P. S. G. (1983). The vertebrate scratch reflex. Symposia of the Society for Experimental Biology(37), 383–403 Some sensory neurons can be activated by stimulation with an external object such as a parasite on the body surface. Alternatively, some sensory neurons can respond to a chemical stimulus that produces an itch sensation. During a scratch reflex, a nearby limb reaches toward and rubs against the site on the body surface that has been stimulated. The scratch reflex has been extensively studied to understand the functioning of biological neural network, neural networks in vertebrates. Despite decades of research, key aspects of the scratch reflex are still unknown, such as the neural mechanisms by which the reflex is terminated. Scratch reflex in dogs Most dogs will exhibit a scratch reflex when they are stimulated in the saddle re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scratch Reflex
The scratch reflex is a response to activation of sensory neurons whose peripheral terminals are located on the surface of the body.Stein, P. S. G. (1983). The vertebrate scratch reflex. Symposia of the Society for Experimental Biology(37), 383–403 Some sensory neurons can be activated by stimulation with an external object such as a parasite on the body surface. Alternatively, some sensory neurons can respond to a chemical stimulus that produces an itch sensation. During a scratch reflex, a nearby limb reaches toward and rubs against the site on the body surface that has been stimulated. The scratch reflex has been extensively studied to understand the functioning of biological neural network, neural networks in vertebrates. Despite decades of research, key aspects of the scratch reflex are still unknown, such as the neural mechanisms by which the reflex is terminated. Scratch reflex in dogs Most dogs will exhibit a scratch reflex when they are stimulated in the saddle re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atopic Dermatitis
Atopic dermatitis (AD), also known as atopic eczema, is a long-term type of inflammation of the skin (dermatitis). It results in puritis, itchy, red, swollen, and cracked skin. Clear fluid may come from the affected areas, which often thickens over time. While the condition may occur at any age, it typically starts in childhood, with changing severity over the years. In children under one year of age, much of the body may be affected. As children get older, the areas on the insides of the knees and elbows are most commonly affected. In adults, the hands and feet are most commonly affected. Scratching the affected areas worsens the symptoms, and those affected have an increased risk of skin infections. Many people with atopic dermatitis develop hay fever or asthma. The cause is unknown but believed to involve genetics, immune system dysfunction, environmental exposures, and difficulties with the Semipermeable membrane, permeability of the skin. If one identical twin is affected, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dermatology
Dermatology is the branch of medicine dealing with the skin.''Random House Webster's Unabridged Dictionary.'' Random House, Inc. 2001. Page 537. . It is a speciality with both medical and surgical aspects. A dermatologist is a specialist medical doctor who manages diseases related to skin, hair, nails, and some cosmetic problems. Etymology Attested in English in 1819, the word "dermatology" derives from the Greek δέρματος (''dermatos''), genitive of δέρμα (''derma''), "skin" (itself from δέρω ''dero'', "to flay") and -λογία '' -logia''. Neo-Latin ''dermatologia'' was coined in 1630, an anatomical term with various French and German uses attested from the 1730s. History In 1708, the first great school of dermatology became a reality at the famous Hôpital Saint-Louis in Paris, and the first textbooks (Willan's, 1798–1808) and atlases ( Alibert's, 1806–1816) appeared in print around the same time.Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cutaneous Larva Migrans
Cutaneous larva migrans (abbreviated CLM) is a skin disease in humans, caused by the larvae of various nematode parasites of the hookworm family ( Ancylostomatidae). These parasites live in the intestines of dogs, cats, and wild animals and should not be confused with other members of the hookworm family for which humans are definitive hosts, namely ''Ancylostoma duodenale'' and ''Necator americanus''. Colloquially called creeping eruption due to its presentation, the disease is also somewhat ambiguously known as " ground itch" or (in some parts of the southern United States) "sandworms", as the larvae like to live in sandy soil. Another vernacular name is plumber's itch. The medical term CLM literally means "wandering larvae in the skin". Symptoms and signs The infection causes a red, intensely pruritic (itchy) eruption, and may look like twirling lesions. The itching can become very painful and if scratched may allow a secondary bacterial infection to develop. Cutaneous larva mi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Body Louse
The body louse (''Pediculus humanus humanus'', also known as ''Pediculus humanus corporis'') is a hematophagic ectoparasite louse that infests humans. It is one of three lice which infest humans, the other two being the head louse, and the crab louse or pubic louse. Despite the name, body lice do not directly live on the host. They lay their eggs on fibres of clothing and only come into contact with the host whenever they need to feed. Since body lice cannot jump or fly, they spread by direct contact with another person or more rarely by contact with clothing or bed sheets that are infested. Body lice are disease vectors and can transmit pathogens that cause human diseases such as epidemic typhus, trench fever, and relapsing fever. In developed countries, infestations are only a problem in areas of poverty where there is poor body hygiene, crowded living conditions, and a lack of access to clean clothing. Outbreaks can also occur in situations where large groups of people a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tinea Pedis Interdigitalis
Dermatophytosis, also known as ringworm, is a fungal infection of the skin. Typically it results in a red, itchy, scaly, circular rash. Hair loss may occur in the area affected. Symptoms begin four to fourteen days after exposure. Multiple areas can be affected at a given time. About 40 types of fungus can cause ringworm. They are typically of the ''Trichophyton'', ''Microsporum'', or ''Epidermophyton'' type. Risk factors include using public showers, contact sports such as wrestling, excessive sweating, contact with animals, obesity, and poor immune function. Ringworm can spread from other animals or between people. Diagnosis is often based on the appearance and symptoms. It may be confirmed by either culturing or looking at a skin scraping under a microscope. Prevention is by keeping the skin dry, not walking barefoot in public, and not sharing personal items. Treatment is typically with antifungal creams such as clotrimazole or miconazole. If the scalp is involved, anti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Shock
Electrical injury is a physiological reaction caused by electric current passing through the body. The injury depends on the density of the current, tissue resistance and duration of contact. Very small currents may be imperceptible or produce a light tingling sensation. A shock caused by low and otherwise harmless current could startle an individual and cause injury due to jerking away or falling. Stronger currents may cause some degree of discomfort or pain, while more intense currents may induce involuntary muscle contractions, preventing the person from breaking free of the source of electricity. Still larger currents result in tissue damage and may trigger ventricular fibrillation or cardiac arrest. Consequences of injury from electricity may include amputations, bone fractures and orthopedic and musculoskeletal injuries. If death results from an electric shock the cause of death is generally referred to as electrocution. Electric injury occurs upon contact of a body part ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noxious Stimulus
A noxious stimulus is a stimulus strong enough to threaten the body’s integrity (i.e. cause damage to tissue). Noxious stimulation induces peripheral afferents responsible for transducing pain (including A-delta and C- nerve fibers, as well as free nerve endings), throughout the nervous system of an organism. The ability to perceive noxious stimuli is a prerequisite for nociception, which itself is a prerequisite for nociceptive pain. A noxious stimulus has been seen to drives nocifensive behavioral responses, which are responses to noxious or painful stimuli. These include reflexive, escape behaviors, to avoid harm to an organism's body. Because of rare genetic conditions that inhibit the ability to perceive physical pain, such acongenital insensitivity to pain and anhydrosis (CIPA) noxious stimulation does not invariably lead to tissue damage. Noxious stimuli can either be mechanical (e.g. pinching or other tissue deformation), chemical (e.g. exposure to acid or irritan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yawning
A yawn is a reflex lasting 4-7 seconds, and is characterized by a long inspiratory phase with gradual mouth gaping, followed by a brief climax (or acme) with muscle stretching, and a rapid expiratory phase with muscle relaxation. For fish and birds, this is described as gradual mouth gaping, staying open for at least 3 seconds and subsequently a rapid closure of the mouth. Almost all vertebrate animals, including mammals, birds, reptiles, amphibians, and even fish, experience yawning. The study of yawning is called chasmology. Yawning (oscitation) most often occurs in adults immediately before and after sleep, during tedious activities and as a result of its contagious quality. It is commonly associated with tiredness, stress, sleepiness, boredom, or even hunger. In humans, yawning is often triggered by the perception that others are yawning (for example, seeing a person yawning, or talking to someone on the phone who is yawning). This is a typical example of positive feedb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
