ingestion

Examples of ingestion in the following topics:

• Ingestion

  • For animals, the first step is ingestion, the act of taking in food.
  • The first step in this process is ingestion: taking in food through the mouth.
  • Besides nutritional items, other substances may be ingested, including medications (where ingestion is termed oral administration) and substances considered inedible, such as insect shells.
  • The first step in obtaining nutrition is ingestion.
  • Describe the process of ingestion and its role in the digestive system

• Invertebrate Digestive Systems

  • Ingested material enters the mouth and passes through a hollow, tubular cavity.
  • Once the food is ingested through the mouth, it passes through the esophagus and is stored in an organ called the crop; then it passes into the gizzard where it is churned and digested.
  • (a) A gastrovascular cavity has a single opening through which food is ingested and waste is excreted, as shown in this hydra and in this jellyfish medusa.
  • (b) An alimentary canal has two openings: a mouth for ingesting food and an anus for eliminating waste, as shown in this nematode.

• Plant Defenses Against Herbivores

  • Many metabolites are toxic and can even be lethal to animals that ingest them.
  • Some compounds become toxic after ingestion; for instance, glycol cyanide in the cassava root releases cyanide only upon ingestion by the herbivore.

• Digestive Systems

  • It is responsible for processing ingested food and liquids.
  • The functions of the digestive system can be summarized as follows: ingestion (eat food), digestion (breakdown of food), absorption (extraction of nutrients from the food), and defecation (removal of waste products).

• Neural Responses to Food

  • The first phase of ingestion, called the cephalic phase, is controlled by the neural response to the stimulus provided by food.
  • Gastric acids and enzymes process the ingested materials.

• Cell Structure, Metabolism, and Motility

  • Amoebas and some other heterotrophic protist species ingest particles by a process called phagocytosis in which the cell membrane engulfs a food particle and brings it inward, pinching off an intracellular membranous sac, or vesicle, called a food vacuole .
  • The vesicle containing the ingested particle, the phagosome, then fuses with a lysosome containing hydrolytic enzymes to produce a phagolysosome, which breaks down the food particle into small molecules that diffuse into the cytoplasm for use in cellular metabolism.

• Vertebrate Digestive Systems

  • Vertebrates may have a single stomach, several stomach chambers, or accessory organs that help to break down ingested food.
  • These chambers contain many microbes that break down cellulose and ferment ingested food.

• Protists as Primary Producers, Food Sources, and Symbionts

  • Certain anaerobic parabasalid species exist in the digestive tracts of termites and wood-eating cockroaches where they contribute an essential step in the digestion of cellulose ingested by these insects as they bore through wood.

• Transforming Chemical Energy

  • Organisms ingest large molecules, like carbohydrates, proteins, and fats, and convert them into smaller molecules like carbon dioxide and water.

• Plant Defenses Against Pathogens

  • Many metabolites are toxic and can even be lethal to animals that ingest them.