Drinking is the act of
ingesting
Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in a substance through the mouth into the gastrointestinal tract, such as through eating or drinking. In single-celled organisms ingesti ...
water or other
liquid
A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...
s into the body through the
mouth
In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on ...
,
proboscis, or elsewhere. Humans drink by
swallowing
Swallowing, sometimes called deglutition in scientific contexts, is the process in the human or animal body that allows for a substance to pass from the mouth, to the pharynx, and into the esophagus, while shutting the epiglottis. Swallowing i ...
, completed by
peristalsis in the
esophagus. The physiological processes of drinking vary widely among other
animals.
Most animals
drink water to maintain
bodily hydration, although many can survive on the water gained from their food. Water is required for many
physiological
Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
processes. Both inadequate and (less commonly) excessive water intake are associated with health problems.
Methods of drinking
In humans
When a
liquid
A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...
enters a human
mouth
In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on ...
, the
swallowing
Swallowing, sometimes called deglutition in scientific contexts, is the process in the human or animal body that allows for a substance to pass from the mouth, to the pharynx, and into the esophagus, while shutting the epiglottis. Swallowing i ...
process is completed by
peristalsis which delivers the liquid through the
esophagus to the
stomach; much of the activity is abetted by gravity. The liquid may be poured from the hands or
drinkware may be used as vessels. Drinking can also be performed by acts of
inhalation
Inhalation (or Inspiration) happens when air or other gases enter the lungs.
Inhalation of air
Inhalation of air, as part of the cycle of breathing, is a vital process for all human life. The process is autonomic (though there are exceptions ...
, typically when imbibing hot liquids or drinking from a spoon. Infants employ a method of suction wherein the lips are pressed tight around a source, as in
breastfeeding: a combination of breath and tongue movement creates a vacuum which draws in liquid.
[Flint, pp. 137–138.]
In other land mammals
By necessity,
terrestrial animals in captivity become accustomed to drinking water, but most free-roaming animals stay hydrated through the fluids and moisture in fresh food,
[Mayer, p. 59.] and learn to actively seek foods with high fluid content.
When conditions impel them to drink from bodies of water, the methods and motions differ greatly among species.
[Broom, p. 105.]
Cats
The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of t ...
,
canines, and
ruminants all lower the neck and lap in water with their powerful tongues.
[ Cats and canines lap up water with the tongue in a spoon-like shape.][Smith, p. 238.] Canines lap water by scooping it into their mouth with a tongue which has taken the shape of a ladle. However, with cats, only the tip of their tongue (which is smooth) touches the water, and then the cat quickly pulls its tongue back into its mouth which soon closes; this results in a column of liquid being pulled into the cat's mouth, which is then secured by its mouth closing. Ruminants and most other herbivores partially submerge the tip of the mouth in order to draw in water by means of a plunging action with the tongue held straight.[Smith, p. 237.] Cats drink at a significantly slower pace than ruminants, who face greater natural predation hazards.[
Many desert animals do not drink even if water becomes available, but rely on eating ]succulent plant
In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word ''succulent'' comes from the Latin word ''sucus'', meani ...
s.[ In cold and frozen environments, some animals like hares, tree squirrels, and bighorn sheep resort to consuming snow and icicles. In savannas, the drinking method of giraffes has been a source of speculation for its apparent defiance of gravity; the most recent theory contemplates the animal's long neck functions like a plunger pump. Uniquely, ]elephants
Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantidae and ...
draw water into their trunks and squirt it into their mouths.[
]
In birds
Most birds scoop or draw water into the buccal areas of their bills, raising and tilting their heads back to drink. An exception is the common pigeon which can suck in water directly by inhalation.[
]
In insects
Most insects obtain adequate water from their food: When dehydrated from a lack of moist food, however, many species will drink from standing water. Additionally, all terrestrial insects constantly absorb a certain amount of the air's humidity through their cuticles. Some desert insects, such as '' Onymacris unguicularis'', have evolved to drink substantially from nighttime fog.
In marine life
Amphibian
Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...
s and aquatic animals which live in freshwater
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
do not need to drink: they absorb water steadily through the skin by osmosis.[Curtis, p. 569.] Saltwater fish, however, drink through the mouth as they swim, and purge the excess salt through the gills.[ Saltwater fishes do drink plenty of water and excrete a small volume of concentrated urine.
]
Hydration and dehydration
Like nearly all other life forms, humans require water for tissue hydration. Lack of hydration causes thirst, a desire to drink which is regulated by the hypothalamus in response to subtle changes in the body's electrolyte
An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon dis ...
levels and blood volume. A decline in total body water is called dehydration and will eventually lead to death by hypernatremia. Methods used in the management of dehydration include assisted drinking or oral rehydration therapy.
An overconsumption of water can lead to water intoxication, which can dangerously dilute the concentration of salts in the body. Overhydration sometimes occurs among athletes and outdoor laborers, but it can also be a sign of disease or damage to the hypothalamus. A persistent desire to drink inordinate quantities of water is a psychological condition termed polydipsia. It is often accompanied by polyuria and may itself be a symptom of diabetes mellitus or diabetes insipidus.[Provan, p. 129.]
Human water requirements
A daily intake of water is required for the normal physiological functioning of the human body
The human body is the structure of a Human, human being. It is composed of many different types of Cell (biology), cells that together create Tissue (biology), tissues and subsequently organ systems. They ensure homeostasis and the life, viabi ...
. The USDA recommends a daily intake of ''total water'': not necessarily by drinking but by consumption of water contained in other beverages and foods. The recommended intake is 3.7 liters (appx. 1 gallon) per day for an adult male, and 2.7 liters (appx. 0.75 gallon) for an adult female.
Other sources, however, claim that a high intake of fresh drinking water, separate and distinct from other sources of moisture, is necessary for good health – eight servings per day of eight fluid ounces (1.8 liters, or 0.5 gallon) is the amount recommended by many nutritionists, although there is no scientific evidence supporting this recommendation.
Evidence-based hydration experts say that the amount of drinking water needed depends on ambient temperature, activity level, body size, and sweat rate.[How much water do you actually need? Here's the science](_blank)
/ref> Research shows drinking when thirsty will maintain hydration to within about 2% of the needed level. Drinking beyond thirst might be beneficial for people who need to perform tasks that require intense concentration, and those with kidney disease
Kidney disease, or renal disease, technically referred to as nephropathy, is damage to or disease of a kidney. Nephritis is an inflammatory kidney disease and has several types according to the location of the inflammation. Inflammation can ...
, kidney stones, urinary tract infections, and people with a weak sense of thirst (which may include more older people).
Alcoholic beverages
The term “drinking” is often used metonymically for the consumption of alcoholic beverage
An alcoholic beverage (also called an alcoholic drink, adult beverage, or a drink) is a drink that contains ethanol, a type of alcohol that acts as a drug and is produced by fermentation of grains, fruits, or other sources of sugar. The c ...
s. Most cultures throughout history have incorporated some number of the wide variety of "strong drinks" into their meals, celebrations, ceremonies, toasts and other occasions. Evidence of fermented drinks in human culture goes back as early as the Neolithic Period, and the first pictorial evidence can be found in Egypt around 4,000 BC.
Alcohol consumption has developed into a variety of well-established drinking cultures around the world. Despite its popularity, alcohol consumption poses significant health risks. Alcohol abuse
Alcohol abuse encompasses a spectrum of unhealthy alcohol drinking behaviors, ranging from binge drinking to alcohol dependence, in extreme cases resulting in health problems for individuals and large scale social problems such as alcohol-relat ...
and the addiction of alcoholism are common maladies in developed countries worldwide. A high rate of consumption can also lead to cirrhosis, gastritis, gout, pancreatitis, hypertension
Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...
, various forms of cancer, and numerous other illnesses.[Fiebach, p. 387.]
See also
* Eating
* Hydration (disambiguation)
References
Bibliography
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External links
"Are You Drinking Enough?"
recommendations by the European Hydration Institute (Madrid)
{{Authority control
Body water
Drinking culture
Ethology
Physiology
Nutrition
Food and drink