Ingestion is the consumption of a substance by an

organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells ( cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fu ...

. In

animal Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage ...

s, 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 ingestion takes place by absorbing a substance through the

cell membrane The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment (t ...

. Besides

nutrition Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It provides organisms with nutrients, which can be metabolized to create energy and chemical structures. Failure to obtain sufficient ...

al items, substances that may be ingested include

medication A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the medical field and ...

(where ingestion is termed

oral administration Oral administration is a route of administration where a substance is taken through the mouth. Per os abbreviated to P.O. is sometimes used as a direction for medication to be taken orally. Many medications are taken orally because they are ...

), recreational drugs, and substances considered inedible, such as foreign bodies or excrement. Ingestion is a common route taken by

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a g ...

s and poisons entering the body. Ingestion can also refer to a mechanism picking up something and making it enter an internal hollow of that mechanism, e.g. "''a grille was fitted to prevent the pump from ingesting

driftwood __NOTOC__ Driftwood is wood that has been washed onto a shore or beach of a sea, lake, or river by the action of winds, tides or waves. In some waterfront areas, driftwood is a major nuisance. However, the driftwood provides shelter and fo ...

''".

Pathogens

Some

s are transmitted via ingestion, including

virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsk ...

es,

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

, and

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson h ...

s. Most commonly, this takes place via the faecal-oral route. An intermediate step is often involved, such as

drinking water Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, ...

contaminated by faeces or food prepared by workers who fail to practice adequate hand-washing, and is more common in regions where untreated sewage is common.

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 immediately due to any external injury. Diseases are often known to be medical conditions that a ...

s transmitted via the fecal-oral route include

hepatitis A Hepatitis A is an infectious disease of the liver caused by ''Hepatovirus A'' (HAV); it is a type of viral hepatitis. Many cases have few or no symptoms, especially in the young. The time between infection and symptoms, in those who develop the ...

polio Poliomyelitis, commonly shortened to polio, is an infectious disease caused by the poliovirus. Approximately 70% of cases are asymptomatic; mild symptoms which can occur include sore throat and fever; in a proportion of cases more severe sy ...

, and cholera. Some pathogenic organisms are typically ingested by other routes. *

Larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e of the parasite '' Trichinella'' encyst within muscles and are transmitted when a new host eats the infected flesh of a former host animal. * The parasite '' Dracunculus'' is ingested in

, which is contaminated with larvae released as the parasite emerges from the host's skin. * The bacterium '' Salmonella'' most commonly infects humans via consumption of undercooked eggs.

Foreign objects

Disk batteries, also called button cells, are often mistakenly ingested, particularly by children and the elderly. They may be mistaken for a

pill because of their size and shape, or they may be swallowed after being held in the mouth while the battery is being changed. Battery ingestion can cause medical problems including blocked

airway The respiratory tract is the subdivision of the respiratory system involved with the process of respiration in mammals. The respiratory tract is lined with respiratory epithelium as respiratory mucosa. Air is breathed in through the nose t ...

vomiting Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenter ...

, irritability, persistent drooling, and rash (due to

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow t ...

metal

allergy Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derm ...

Abnormal ingestion

Pica is an abnormal appetite for non- nutritive objects or for food items in a form not normally eaten, such as flour. Coprophagia is the consumption of feces, an abnormal ingestive behavior common in some animals.

References

{{Ethology Digestive system Ethology Mouth