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Perspiration, also known as sweating, is the production of fluids secreted by the
sweat gland Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate Vertebrates () comprise all species of an ...
s in the
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have differ ...

skin
of
mammal Mammals (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be i ...
s. Two types of
sweat gland Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate Vertebrates () comprise all species of an ...
s can be found in humans:
eccrine gland Eccrine sweat glands (; from ''ekkrinein'' "secrete"; sometimes called merocrine glands) are the major sweat glands of the human body, found in virtually all skin, with the highest density in palm and soles, then on the head, but much less on the ...
s and
apocrine gland Apocrine () is a term used to classify exocrine glands in the study of histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology Biology is the natural science that studies life and living organism ...
s. The eccrine sweat glands are distributed over much of the body and are responsible for secreting the watery, brackish sweat most often triggered by excessive body temperature. The apocrine sweat glands are restricted to the armpits and a few other areas of the body and produce an odorless, oily, opaque secretion which then gains its characteristic odor from bacterial decomposition. In
human Humans (''Homo sapiens'') are the most abundant and widespread species In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes ...

human
s, sweating is primarily a means of
thermoregulation Thermoregulation is the ability of an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxo ...
, which 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 (10–15 g/min·m2), but is less in children prior to puberty.
Evaporation Evaporation is a type of that occurs on the of a as it changes into the gas phase. The surrounding gas must not be saturated with the evaporating substance. When the molecules of the liquid collide, they transfer energy to each other bas ...

Evaporation
of sweat from the skin surface has a cooling effect due to
evaporative cooling An evaporative cooler (also evaporative air conditioner, swamp cooler, swamp box, desert cooler and wet air cooler) is a device that cools air through the evaporation Evaporation is a type of that occurs on the of a as it changes int ...
. Hence, in
hot
hot
weather, or when the individual's muscles heat up due to exertion, more sweat is produced. Animals with few sweat glands, such as
dog The dog or domestic dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a Domestication, domesticated descendant of the wolf which is characterized by an upturning tail. The dog Origin of the domestic dog, derived from an Pleistocene ...

dog
s, accomplish similar temperature regulation results by panting, which evaporates water from the moist lining of the oral cavity and
pharynx The pharynx (plural: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea – the tubes going down to the stomach and the lungs. It is found in vertebrates and invertebrates, thou ...

pharynx
. Although sweating is found in a wide variety of mammals, relatively few (exceptions include humans and
horses The horse (''Equus ferus caballus'') is a Domestication, domesticated odd-toed ungulate, one-toed ungulate, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two Extant taxon, extant subspecies of wild horse, ''Equus ferus ...

horses
) produce large amounts of sweat in order to cool down.


Etymology

1610s, "a breathing through," a sense now obsolete, from French perspiration (1560s), noun of action from perspirer "perspire," from Latin perspirare "blow or breathe constantly," from per "through" (from PIE root *per- (1) "forward," hence "through") + spirare "to breathe, blow" (see spirit (n.)). Applied by 1620s to "excretion of invisible moistures through the skin," hence its later use as a euphemism for "sweat" (1725).


Definitions

* The words diaphoresis and
hidrosis Hyperhidrosis is a condition characterized by abnormally increased perspiration, sweating, in excess of that required for regulation of body temperature. Although primarily a physical burden, hyperhidrosis can deteriorate quality of life from a psyc ...
both can mean either perspiration (in which
sense A sense is a biological system used by an organism for sensation, the process of gathering information about the world and responding to Stimulus (physiology), stimuli. (For example, in the human body, the brain receives signals from the senses ...
they are
synonym A synonym is a word, morpheme A morpheme is the smallest meaningful lexical item in a language. A morpheme is not a word. The difference between a morpheme and a word is that a morpheme bound and free morphemes, sometimes does not stand alone ...
ous with ''sweating'') or excessive perspiration (in which sense they can be either synonymous with
hyperhidrosis Hyperhidrosis is a condition characterized by abnormally increased sweating, in excess of that required for regulation of body temperature. Although primarily a physical burden, hyperhidrosis can deteriorate quality of life from a psychological, e ...

hyperhidrosis
or differentiable from it only by clinical criteria involved in narrow specialist senses of the words). *
Hypohidrosis Hypohidrosis is a disorder in which a person exhibits diminished sweating in response to appropriate stimuli. In contrast with hyp''er''hidrosis, which is a socially troubling yet often benign {{Unreferenced, date=June 2019, bot=noref (GreenC bot ...
is decreased sweating from whatever cause. *
Focal hyperhidrosis Focal hyperhidrosis, also known as primary hyperhidrosis, is a disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not due to any immediate ex ...
is increased or excessive sweating in certain regions such as the underarm, palms, soles, face, or groin. *
Hyperhidrosis Hyperhidrosis is a condition characterized by abnormally increased sweating, in excess of that required for regulation of body temperature. Although primarily a physical burden, hyperhidrosis can deteriorate quality of life from a psychological, e ...

Hyperhidrosis
is excessive sweating, usually
secondary Secondary is an adjective meaning "second" or "second hand". It may refer to: * Secondary (chemistry), term used in organic chemistry to classify various types of compounds * The group of (usually at least four) defensive backs in gridiron football ...
to an underlying condition (in which case it is called secondary hyperhidrosis) and usually involving the body as a whole (in which case it is called
generalized hyperhidrosis Hyperhidrosis is a condition characterized by abnormally increased perspiration, sweating, in excess of that required for regulation of body temperature. Although primarily a benign physical burden, hyperhidrosis can deteriorate quality of life fro ...
). *Hidromeiosis is a reduction in sweating that is due to blockages of sweat glands in humid conditions. *A substance or medicine that causes perspiration is a sudorific or sudatory.


Signs and symptoms

Sweat contributes to
body odor Body odor is present in all animals, including humans Humans (''Homo sapiens'') are the most populous and widespread species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of ...
when it is metabolized by
bacteria Bacteria (; common noun bacteria, singular bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typ ...

bacteria
on the
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have differ ...

skin
. Medications that are used for other treatments and diet also affect odor. Some medical conditions, such as
kidney failure Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys are functioning at less than 15% of normal levels. Kidney failure is classified as either acute kidney failure, which develops rapidly and may res ...
and
diabetic ketoacidosis Diabetic ketoacidosis (DKA) is a potentially life-threatening complication of diabetes mellitus Diabetes mellitus (DM), commonly known as diabetes, is a group of metabolic disorders characterized by a high blood sugar level over a prolonged p ...
, can also affect sweat odor. Areas that produce excessive sweat usually appear pink or white, but, in severe cases, may appear cracked, scaly, and soft.Excessive Sweating Information on Healthline.com
Retrieved on 2010-01-25.


Causes

Diaphoresis is a
non-specific symptom Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showi ...
or sign, which means that it has many possible causes. Some causes of diaphoresis include physical exertion,
menopause Menopause, also known as the climacteric, is the time in women's lives when menstrual periods stop permanently, and they are no longer able to bear children. Menopause usually occurs between the age of 48 and 52. Medical professionals often ...
, fever, ingestion of toxins or irritants, and high environmental temperature. Strong emotions (anger, fear, anxiety) and recall of past trauma can also trigger sweating. The vast majority of sweat glands in the body are innervated by sympathetic
cholinergic Cholinergic agents are compounds which mimic the action of and/or . In general, the word "" describes the various containing the . Found in most animal tissues, choline is a primary component of the and functions with as a basic constitu ...
neurons. Sympathetic postganglionic neurons typically secrete
norepinephrine Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical , CH4; is among the simplest organic compounds. In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and ...

norepinephrine
and are named sympathetic
adrenergicAdrenergic means "working on adrenaline (epinephrine) or noradrenaline (norepinephrine)" (or on their receptors). When not further qualified, it is usually used in the sense of enhancing or mimicking the effects of epinephrine and norepinephrine in t ...
neurons; however, the sympathetic postganglionic neurons that innervate sweat glands secrete
acetylcholine Acetylcholine (ACh) is an organic chemical that functions in the brain and body of many types of animals (including humans) as a neurotransmitter—a chemical message released by nerve cells to send signals to other cells, such as neurons, musc ...

acetylcholine
and hence are termed sympathetic cholinergic neurons. Sweat glands, piloerector muscles, and some blood vessels are innervated by sympathetic cholinergic neurons.


Pathological sweating

Diaphoresis may be associated with some abnormal conditions, such as
hyperthyroidism Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormones by the thyroid gland. Thyrotoxicosis is the condition that occurs due to excessive thyroid hormone of any cause and therefore includes hyperthyroidism. ...
and shock. If it is accompanied by unexplained
weight loss Weight loss, in the context of medicine, health, or physical fitness Physical fitness is a state of health Health, according to the World Health Organization, is "a state of complete physical, Mental health, mental and social well-bein ...

weight loss
or
fever Fever, also referred to as pyrexia, is defined as having a temperature Temperature ( ) is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy Thermal radiation in visible light can be seen on th ...

fever
or by
palpitation Palpitations are perceived abnormalities of the heartbeat characterized by awareness of cardiac muscle contractions in the chest, which is further characterized by the hard, fast and/or irregular beatings of the heart. Symptoms include a rapid ...
s,
shortness of breath Shortness of breath (SOB), also known as dyspnea (BrE British English (BrE) is the standard dialect A standard language (also standard variety, standard dialect, and standard) is a language variety that has undergone substantial codificat ...
, or chest discomfort, it suggests serious illness. Diaphoresis is also seen in an acute
myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynamics, dynamics of blood flow. The circulatory sy ...

myocardial infarction
(heart attack), from the increased firing of the
sympathetic nervous system The sympathetic nervous system (SNS) is one of two divisions of the autonomic nervous system, along with the parasympathetic nervous system. The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes co ...
, and is frequent in
serotonin syndrome Serotonin syndrome (SS) is a group of symptoms that may occur with the use of certain serotonergic medications or Recreational drug use, drugs. The degree of symptoms can range from mild to severe, including a potentiality of death. Symptoms in m ...
. Diaphoresis can also be caused by many types of infections, often accompanied by
fever Fever, also referred to as pyrexia, is defined as having a temperature Temperature ( ) is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy Thermal radiation in visible light can be seen on th ...

fever
and/or
chills Chills is a feeling of coldness occurring during a high fever, but sometimes is also a common symptom which occurs alone in specific people. It occurs during fever due to the release of cytokines and prostaglandins as part of the Inflammation, ...
. Most infections can cause some degree of diaphoresis and it is a very common symptom in some serious infections such as
malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign fo ...

malaria
and
tuberculosis Tuberculosis (TB) is an infectious disease An infection is the invasion of an organism's body Tissue (biology), tissues by Pathogen, disease-causing agents, their multiplication, and the reaction of host (biology), host tissues to the in ...

tuberculosis
. In addition, pneumothorax can cause diaphoresis with splinting of the chest wall.
Neuroleptic malignant syndrome Neuroleptic malignant syndrome (NMS) is a rare but life-threatening reaction that can occur in response to antipsychotic, neuroleptic or antipsychotic medication. Symptoms include hyperpyrexia, high fever, confusion, rigid muscles, variable blood ...
and other malignant diseases (e.g. leukemias) can also cause diaphoresis. Diabetics relying on
insulin Insulin (, from Latin ''insula'', 'island') is a peptide hormone produced by beta cells of the pancreatic islets; it is considered to be the main Anabolism, anabolic hormone of the body. It regulates the metabolism of carbohydrates, fats and p ...

insulin
shots or oral medications may have low
blood sugar The blood sugar level, blood sugar concentration, or blood glucose level is the concentration of glucose Glucose is a simple with the . Glucose is the most abundant , a subcategory of s. Glucose is mainly made by and most during from water ...
(
hypoglycemia Hypoglycemia, also known as low blood sugar, is a fall in blood sugar The blood sugar level, blood sugar concentration, or blood glucose level is the concentration of glucose Glucose is a simple with the . Glucose is the most abundant , a ...

hypoglycemia
), which can also cause diaphoresis. Drugs (including
caffeine Caffeine is a central nervous system The central nervous system (CNS) is the part of the nervous system In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structu ...

caffeine
,
morphine Morphine is a of the family that is found naturally in a dark brown, resinous form, from the poppy plant ('). It can be taken orally or injected. It acts directly on the (CNS) to induce analgesia and alter perception and emotional respons ...

morphine
,
alcohol In chemistry, alcohol is an organic compound that carries at least one hydroxyl functional group (−OH) bound to a Saturated and unsaturated compounds, saturated carbon atom. The term alcohol originally referred to the primary alcohol ethan ...
, antidepressants and certain antipsychotics) may be causes, as well as withdrawal from
alcohol In chemistry, alcohol is an organic compound that carries at least one hydroxyl functional group (−OH) bound to a Saturated and unsaturated compounds, saturated carbon atom. The term alcohol originally referred to the primary alcohol ethan ...
,
benzodiazepines Benzodiazepines (BZD, BDZ, BZs), sometimes called "benzos", are a class of psychoactive drug A psychoactive drug, psychopharmaceutical, psychoactive agent, or psychotropic drug, is a chemical substance that changes nervous system function and r ...
,
nonbenzodiazepines Nonbenzodiazepines (,) sometimes referred to colloquially as Z-drugs (as many of them begin with the letter "z"), are a class of psychoactive A psychoactive drug, psychopharmaceutical, or psychotropic drug is a chemical substance that changes ner ...

nonbenzodiazepines
or
narcotic The term narcotic (, from ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply as ...
painkiller dependencies.
Sympathetic nervous system The sympathetic nervous system (SNS) is one of two divisions of the autonomic nervous system, along with the parasympathetic nervous system. The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes co ...
stimulants such as
cocaine Cocaine (from , from , ultimately from Quechuan languages, Quechua: ''kúka'') is a tropane alkaloid and stimulant drug obtained primarily from the leaves of two coca species native to South America, ''Erythroxylum coca'' and ''Erythroxylu ...

cocaine
and
amphetamines#REDIRECT Substituted amphetamine#REDIRECT Substituted amphetamine Substituted amphetamines are a class of compounds based upon the amphetamine structure; it includes all derivative In mathematics Mathematics (from Ancient Greek, Gre ...
have also been associated with diaphoresis. Diaphoresis due to ectopic
catecholamine A catecholamine (; abbreviated CA) is a monoamine neurotransmitter Monoamine neurotransmitters are s and s that contain one group connected to an by a two-carbon chain (such as -CH2-CH2-). Examples are , and . All monoamines are derived ...

catecholamine
is a classic symptom of a
pheochromocytoma Pheochromocytoma (PHEO or PCC) is a rare tumor of the adrenal medulla composed of chromaffin cells, also known as pheochromocytes. When a tumor composed of the same cells as a pheochromocytoma develops outside the adrenal gland, it is referred t ...

pheochromocytoma
, a rare
tumor A neoplasm () is a type of abnormal and excessive growth of tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth ...

tumor
of the
adrenal gland The adrenal glands (also known as suprarenal glands) are endocrine gland Endocrine glands are ductless glands of the endocrine system The endocrine system is a messenger system comprising feedback loops of the hormones released by interna ...

adrenal gland
.
Acetylcholinesterase Acetylcholinesterase ( HGNC symbol ACHE; EC 3.1.1.7), also known as AChE or acetylhydrolase, is the primary cholinesterase In biochemistry Biochemistry or biological chemistry, is the study of es within and relating to living s. A su ...

Acetylcholinesterase
inhibitors (e.g. some
insecticides Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect Egg (biology), eggs and larvae, respectively. Insecticides are used in agriculture, medicine, Industry (manufacturing), industry and by c ...
) also cause contraction of sweat gland smooth muscle leading to diaphoresis.
Mercury Mercury usually refers to: * Mercury (planet) Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman g ...

Mercury
is well known for its use as a diaphoretic, and was widely used in the 19th and early 20th century by physicians to "purge" the body of an illness. However, due to the high toxicity of mercury, secondary symptoms would manifest, which were erroneously attributed to the former disease that was being treated with mercurials. Infantile
acrodynia Acrodynia is a condition of pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or r ...
(childhood mercury poisoning) is characterized by excessive perspiration. A clinician should immediately consider acrodynia in an afebrile child who is sweating profusely. Some people can develop a
sweat allergyA sweat allergy is the exacerbation of atopic dermatitis associated with an Hyperthermia, elevated body temperature and resulting increases in the production of Perspiration, sweat. It appears as small reddish Cutaneous condition, wheals that become ...
. The allergy is not due to the sweat itself but instead to an allergy-producing protein secreted by bacteria found on the skin. Tannic-acid has been found to suppress the allergic response along with showering.


Hyperhidrosis

In some people, the body's mechanism for cooling itself is overactive—so overactive that they may sweat four or five times more than is typical.International Hyperhidrosis Society: About Hyperhidrosis
, Retrieved on 2010-01-25.
Millions of people are affected by this condition, but more than half never receive treatment due to embarrassment or lack of awareness. While it most commonly affects the
armpits The axilla (also, armpit, underarm or oxter) is the area on the human body directly under the joint A joint or articulation (or articular surface) is the connection made between bones in the body which link the skeletal system into a functional ...
, feet, and hands, it is possible for someone to experience this condition over their whole body. The face is another common area for hyperhidrosis to be an issue. Sweating uncontrollably is not always expected and may be embarrassing to sufferers of the condition. It can cause both physiological and emotional problems in patients. It is generally an inherited problem that is found in each ethnic group. It is not life-threatening, but it is threatening to a person's quality of life. Treatments for hyperhidrosis include
antiperspirants A deodorant is a substance applied to the body to prevent or mask body odor Body odor is present in all animals, including humans Humans (''Homo sapiens'') are the most populous and widespread species In biology, a species is the bas ...
and surgical removal of sweat glands. In severe cases,
botulinum toxin Botulinum toxin (Botox) is a neurotoxin, neurotoxic protein produced by the bacteria, bacterium ''Clostridium botulinum'' and related species. It prevents the release of the neurotransmitter acetylcholine from axon endings at the neuromuscular ...
injections or surgical cutting of nerves that stimulate the excessive sweating (
Endoscopic thoracic sympathectomy Endoscopic thoracic sympathectomy (ETS) is a surgical procedure in which a portion of the sympathetic nerves, sympathetic nerve trunk in the thoracic region is destroyed. ETS is used to treat excessive sweating in certain parts of the body (focal hy ...
) may be an option.


Night sweats

Night sweats, also known as nocturnal hyperhidrosis, is the occurrence of excessive sweating during sleep. The person may or may not also perspire excessively while awake. One of the most common causes of night sweats in women over 40 is the hormonal changes related to menopause and perimenopause. This is a very common occurrence during the menopausal transition years. While night sweats might be relatively harmless, it can also be a sign of a serious underlying disease. It is important to distinguish night sweats due to medical causes from those that occur simply because the sleep environment is too warm, either because the bedroom is unusually hot or because there are too many covers on the bed. Night sweats caused by a medical condition or infection can be described as "severe hot flashes occurring at night that can drench sleepwear and sheets, which are not related to the environment". Some of the underlying medical conditions and infections that cause these severe night sweats can be life-threatening and should promptly be investigated by a medical practitioner.


Mechanism

Sweating allows the body to regulate its temperature. Sweating is controlled from a center in the preoptic and anterior regions of the brain's
hypothalamus The hypothalamus (from Ancient Greek wikt:ὑπό, ὑπό, "under", and wikt:θάλαμος, θάλαμος, "chamber") is a portion of the brain that contains a number of small Nucleus (neuroanatomy), nuclei with a variety of functions. One of ...

hypothalamus
, where thermosensitive neurons are located. The heat-regulatory function of the hypothalamus is also affected by inputs from temperature receptors in the
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have differ ...

skin
. High skin temperature reduces the hypothalamic set point for sweating and increases the
gain Gain or GAIN may refer to: Science and technology * Gain (electronics) In , gain is a measure of the ability of a (often an ) to increase the or of a from the input to the output port by adding energy converted from some to the signal. ...
of the hypothalamic
feedback Feedback occurs when outputs of a system are routed back as inputs as part of a chain A chain is a assembly of connected pieces, called links, typically made of metal, with an overall character similar to that of a in that it is flexib ...

feedback
system in response to variations in core
temperature Temperature ( ) is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy Thermal radiation in visible light can be seen on this hot metalwork. Thermal energy refers to several distinct physical concept ...

temperature
. Overall, however, the sweating response to a rise in hypothalamic ('core') temperature is much larger than the response to the same increase in average skin temperature. Sweating causes a decrease in core temperature through evaporative cooling at the skin surface. As high energy molecules evaporate from the skin, releasing energy absorbed from the body, the skin and superficial vessels decrease in temperature. Cooled venous blood then returns to the body's core and counteracts rising core temperatures. There are two situations in which the nerves will stimulate the sweat glands, causing perspiration: during physical heat and during emotional stress. In general, emotionally induced sweating is restricted to
palm Palm most commonly refers to: * Palm of the hand, the central region of the front of the hand and a subdivision of the cubit * Palm trees, of family Arecaceae **List of Arecaceae genera * Several Arecaceae#Other plants, other plants known as Palm P ...
s, soles,
armpit The axilla (also, armpit, underarm or oxter) is the area on the human body directly under the joint where the arm connects to the shoulder. It also contains many sweat glands. In humans, the formation of body odor happens mostly in the armpit. ...

armpit
s, and sometimes the
forehead In human anatomy The human body is the structure of a human being. It is composed of many different types of cells that together create tissues and subsequently organ systems. They ensure homeostasis In biology Biology is the natura ...

forehead
, while physical heat-induced sweating occurs throughout the body. People have an average of two to four million sweat glands. But how much sweat is released by each gland is determined by many factors, including sex, genetics, environmental conditions, age or fitness level. Two of the major contributors to sweat rate are an individual's fitness level and weight. If an individual weighs more, sweat rate is likely to increase because the body must exert more energy to function and there is more body mass to cool down. On the other hand, a fit person will start sweating earlier and more readily. As someone becomes fit, the body becomes more efficient at regulating the body's temperature and sweat glands adapt along with the body's other systems. Sweat is not pure
water Water (chemical formula H2O) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known li ...

water
; it always contains a small amount (0.2–1%) of
solute In chemistry Chemistry is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence i ...
. When a person moves from a
cold , a common physiological response to cold, aiming to reduce the loss of body heat in a cold environment File:AntarcticaDomeCSnow.jpg, A photograph of the snow surface at Dome C Station, Antarctica a part of the notoriously cold Polar Platea ...

cold
climate Climate is the long-term pattern of weather Weather is the state of the atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a la ...

climate
to a climate, adaptive changes occur in the sweating mechanisms of the person. This process is referred to as
acclimatization Acclimatization or acclimatisation ( also called acclimation or acclimatation) is the process in which an individual organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual co ...
: 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. The solute loss can be as much as 350 mmol/d (or 90 mmol/d acclimatised) of
sodium Sodium is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical eleme ...

sodium
under the most extreme conditions. 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 Exercise is any bodily activity that enhances or maintains physical fitness Physical fitness is a state of health Health is a state of physical, mental and social well-being Well-being, also known as ''wellness'', ''prudential value ...

exercise
, sodium loss can be very low (less than 5 mmol/d). Sodium concentration in sweat is 30–65 mmol/l, depending on the degree of acclimatisation.


Composition

Sweat is mostly
water Water (chemical formula H2O) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known li ...

water
. A microfluidic model of the eccrine sweat gland provides details on what solutes partition into sweat, their mechanisms of partitioning, and their fluidic transport to the skin surface. Dissolved in the water are trace amounts of
minerals In geology Geology (from the Ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers ...

minerals
,
lactic acid Lactic acid is an organic acid An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, conta ...

lactic acid
, and
urea Urea, also known as carbamide, is an organic compound In , organic compounds are generally any s that contain - . Due to carbon's ability to (form chains with other carbon s), millions of organic compounds are known. The study of the prop ...

urea
. Although the mineral content varies, some measured concentrations are:
sodium Sodium is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical eleme ...

sodium
(),
potassium Potassium is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, b ...

potassium
(),
calcium Calcium is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elem ...

calcium
(), and
magnesium Magnesium is a chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science ...

magnesium
(). Relative to the plasma and extracellular fluid, the concentration of Na+ ions is much lower in sweat (~40 mM in sweat versus ~150 mM in plasma and extracellular fluid). Initially, within
eccrine glands Eccrine sweat glands (; from ''ekkrinein'' "secreteSecretion is the movement of material from one point to another, such as a secreted chemical substance A chemical substance is a form of matter In classical physics and general chemistry, ...
sweat has a high concentration of Na+ ions. In the sweat ducts, the Na+ ions are re-absorbed into tissue by
epithelial sodium channels The epithelial sodium channel (short: ENaC, also: amiloride-sensitive sodium channel) is a membrane-bound ion channel s (typically four per channel), 2 - outer vestibule, 3 - selectivity filter, 4 - diameter of selectivity filter, 5 - phosphoryla ...
(ENaC) that are located on the apical membrane of epithelial cells that form the duct (see Fig. 9 of the reference). Many other
trace elements __NOTOC__ A trace element is a chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all ha ...
are also excreted in sweat, again an indication of their concentration is (although measurements can vary fifteenfold)
zinc Zinc is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

zinc
(),
copper Copper is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elem ...

copper
(),
iron Iron () is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behav ...

iron
(),
chromium Chromium is a chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science tha ...

chromium
(),
nickel Nickel is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elem ...

nickel
(), and
lead Lead is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elements ...

lead
(). Probably many other less-abundant trace minerals leave the body through sweating with correspondingly lower concentrations. Some exogenous organic compounds make their way into sweat as exemplified by an unidentified odiferous "maple syrup" scented compound in several of the species in the mushroom genus ''Lactarius''. In humans, sweat is hypoosmotic relative to
plasma Plasma or plasm may refer to: Science * Plasma (physics), one of the four fundamental states of matter * Plasma (mineral) or heliotrope, a mineral aggregate * Quark–gluon plasma, a state of matter in quantum chromodynamics Biology * Blood plasma ...
(i.e. less ). Sweat is found at moderately acidic to neutral pH levels, typically between 4.5 and 7.0.


Society and culture


Artificial perspiration

Artificial skin capable of sweating similar to natural sweat rates and with the surface texture and wetting properties of regular skin has been developed for research purposes. Artificial perspiration is also available for in-vitro testing, and contains 19 amino acids and the most abundant minerals and metabolites in sweat.


Diagnostics

There is interest in its use in
wearable technology Wearable technology, wearables, fashion technology, smartwear, tech togs, streetwear tech, skin electronics or fashion electronics are smart electronic devices (electronic device with micro-controllers) that are worn close to and/or on the surface ...
. Sweat can be sampled and sensed non-invasively and continuously using electronic tattoos, bands, or patches. However, sweat as a diagnostic fluid presents numerous challenges as well, such as very small sample volumes and filtration (dilution) of larger-sized hydrophilic analytes. Currently the only major commercial application for sweat diagnostics is for infant cystic fibrosis testing based on sweat chloride concentrations.


Art

There has been an example of a
gouache Gouache (; ), body color, or opaque watercolor, is a water-medium paint consisting of natural pigment, water, a binding agent (usually gum arabic '', pictured in a medicinal handbook: Franz Eugen Köhler, ''Köhler's Medizinal-Pflanzen'' ( ...

gouache
painting in which the painting is diluted with sweat.


See also


References


Further reading

* * *


External links

* {{Authority control Animal physiology Body fluids Excretion Reflexes