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Also known as sweating, is the production of fluids secreted by the sweat glands in the skin
Other terms: Sweating, hidrosis, diaphoresis.
There are 2 types of sweat glands: eccrine glands and apocrine glands.
The eccrine sweat glands are distributed over much of the body.
Sweating is primarily a means of thermoregulation.
Thermoregulation is achieved by the water-rich secretion of the eccrine glands.
Maximum sweat rates of an adult can be up to 2–4 liters per hour or 10–14 liters per day.
Sweat rated in children but is less prior to puberty.
The evaporation of sweat from the skin surface has a cooling effect.
In hot weather, or when the individual’s muscles heat up due to exertion, more sweat is produced.
Hypohidrosis refers to decreased sweating.
Focal hyperhidrosis refers to increased or excessive sweating in certain regions such as the underarm, palms, soles, face, or groin.
Hyperhidrosis is excessive sweating, usually involves the body as a whole.
When sweat is metabolized by bacteria on the skin, it can contribute to body odor.
Diet, medications, kidney failure and diabetic ketoacidos can also affect sweat odor.
Diaphoresis is a non-specific symptom or sign, with many possible causes: physical exertion, menopause, fever, ingestion of toxins or irritants, and high environmental temperature. strong emotions and recall of past trauma.
The vast majority of sweat glands in the body are innervated by sympathetic cholinergic neurons.
Sympathetic postganglionic neurons typically secrete norepinephrine and are named sympathetic adrenergic neurons
The sympathetic postganglionic neurons that innervate sweat glands secrete acetylcholine and are termed sympathetic cholinergic neurons.
Sweat glands, piloerector muscles, and some blood vessels are innervated by sympathetic cholinergic neurons.
Sweating allows the body to regulate its temperature, and is controlled from a center in the preoptic and anterior regions of the brain’s hypothalamus, where thermosensitive neurons are located.
The heat-regulatory function of the hypothalamus is also affected by inputs from temperature receptors in the skin.
Sweating decreases the core temperature through evaporative cooling at the skin surface.
The high energy molecules evaporating from the skin, release energy absorbed from the body, as the skin and superficial vessels decrease in temperature.
As a result cooled venous blood then returns to the body’s core and counteracts rising core temperatures.
Diaphoresis may be associated with hyperthyroidism and shock, and accompanied by unexplained weight loss or fever or by palpitations, shortness of breath, or chestnuts discomfort, it suggests serious illness.
Diaphoresis is also seen as accompanying acute myocardial infarction, from the increased firing of the sympathetic nervous system.
It is is frequent in serotonin syndrome, neuroleptic syndrome, and caused by many types of infections, often accompanied by fever and/or chills.
It is a very common symptom in some serious infections such as malaria and tuberculosis.
Associated with pneumothorax, and malignant diseases.
Hypoglycemia is associated with diaphoresis.
A variety of drugs are associated with diaphoresis include: caffeine, morphine, alcohol, antidepressants and certain antipsychotics.
Withdrawal from alcohol, benzodiazepines, nonbenzodiazepines or narcotic painkiller dependencies are associated with diaphoresis.
Sympathetic nervous system stimulation by amphetamines is associated with diaphoresis.
It is a classic symptom of a pheochromocytoma, due to ectopic catecholamine production.
Acetylcholinesterase inhibitors as in some insecticides cause contraction of sweat gland smooth muscle leading to diaphoresis.
Infantile acrodynia, childhood mercury poisoning, is characterized by excessive perspiration.
Sweat allergy is due to allergy-producing protein secreted by bacteria found on the skin.
Hyperhidrosis is overactive sweating at four or five times more than is typical.
Hyperhidrosis most commonly affects the armpits, feet, face and hands, it is possible for someone to experience this condition over their whole body.
Nocturnal hyperhidrosis, night sweats, is the occurrence of excessive sweating during sleep.
Night sweats in women over 40 is commonly caused by hormonal changes related to menopause, and the perimenopausal period.
While night sweats might be relatively harmless, it can also be a sign of a serious underlying disease.
The nerves will stimulate the sweat glands to cause perspiration: during physical activity and during emotional stress.
Emotionally induced sweating is generally restricted to palms, soles, armpits, and sometimes the forehead
Physical heat-induced sweating occurs throughout the body.
There are an average of two to four million sweat glands in people.
How much sweat is released from each gland is determined by many factors that include: gender, genetics, environmental conditions, age and fitness level.
The major contributors to sweat rate are an individual’s fitness level and weight.
Sweat rate increases with increased body weight as more energy must be exerted to function and there is more body mass to cool down.
A fit person starts sweating earlier and more readily, as the body becomes more efficient at regulating the body’s temperature.
Sweat contains a small amount (0.2–1%) of solute.
The solute loss can be as much as 350 mmol/d, or 90 mmol/d acclimatised, of sodium under the most extreme conditions.
Adaptive changes occur in the sweating mechanisms when a person moves from a cold climate to a hot climate, in a process is ref2242ed to as acclimatisation
With acclimatisation the maximum rate of sweating increases and its solute composition decreases.
The volume of water lost in sweat daily is highly variable, ranging from 100 to 8,000 mL/day.
During average intensity exercise, sweat losses can average up to 2 litres of water/hour.
In a cool climate and in the absence of exercise, sodium loss can be less than 5 mmol/d.
Sodium concentration in sweat is 30-65 mmol/l, depending on the degree of acclimatisation.
Sweat is mostly water, and dissolved in the water are trace amounts of minerals, lactic acid, and urea.
Concentrations are: sodium (0.9 gram/liter), potassium (0.2 g/L), calcium (0.015 g/L), and magnesium (0.0013 g/L), zinc (0.4 milligrams/liter), copper (0.3–0.8 mg/l), iron (1 mg/l), chromium (0.1 mg/l), nickel (0.05 mg/l), and lead (0.05 mg/l).
The concentration of Na+ ions is much lower in sweat about 40 mM in sweat versus about 150 mM in plasma and extracellular fluid.
Within eccrine glands sweat has a high concentration of Na+ ions.
Na+ ions are re-absorbed in the swear ducts, into tissue by epithelial sodium channels that are located on the apical membrane of epithelial cells that form the duct.
Sweat is hypoosmotic relative to plasma.
Sweat is found at moderately acidic to neutral pH levels, typically between 4.5 and 7.0.
Sweat is hypoosmotic relative to plasma.
Sweat is found at moderately acidic to neutral pH levels, typically between 4.5 and 7.0.
The only major application for sweat diagnostics is for infant cystic fibrosis testing based on sweat chloride concentrations.