Chewing

Chewing (also called mastication) is a mechanical process that serves to break down food and its initial enzymatic breakdown (digestion). This involves an "up-down movement" in combination with a sideways or forward-backward movement of the lower jaw. The masticatory system is also called the craniomandibular system. As a result, food in the mouth is carried between the molars by the tongue and ground up by them. During chewing, the food is mixed with saliva.

Chewing is followed by swallowing, during which the food pulp is transported through the oesophagus into the digestive tract.

Most vertebrates cannot chew, neither fish nor amphibians nor birds. Snakes, for example, swallow their prey without chewing. Other animals tear pieces out of their prey, such as birds of prey or crocodiles. Many mammals also cannot chew, such as the echidna. Most predators, such as dogs and cats, also chew their food very little and choke down larger pieces.

Chewing, on the other hand, is particularly pronounced in the bovids, which, as ruminants, chew their food twice by transporting the predigested food pulp from the stomach through the oesophagus into the oral cavity once more. The necessity of chewing depends in a strong way on the food, the more cellulose-containing it is, for example as grass, bark etc., the more important the mechanical comminution of the food becomes.

Herbivores that have not developed the evolutionary advantage of chewing in the mouth using grinders rely on more aggressive digestive juices and swallowed stones to mechanically break down plant fibers (gizzard).

The pathological biting of the fingernails in humans is called onychophagia.

See also

• Fletcher