primary digestion

primary digestion

n.

Digestion in the alimentary canal.

---

digestion

1. the act or process of converting food into chemical substances that can be absorbed into the blood and utilized by the body tissues.

2. the subjection of a substance to prolonged heat and moisture, so as to disintegrate and soften it.

Digestion is accomplished by physically breaking down, churning, diluting and dissolving the food substances, and also by splitting them chemically into simpler compounds. Carbohydrates are eventually broken down to monosaccharides (simple sugars); proteins are broken down into amino acids; and fats are absorbed as fatty acids, monoglycerides and glycerol (glycerin).

The digestive process takes place in the alimentary canal or digestive system. The salivary glands, liver, gallbladder and pancreas are located outside the alimentary canal, but they are considered accessory organs of digestion because their secretions provide essential enzymes and other substances.

---

avian digestion

differs markedly from mammals in the mouth; there are no teeth, dental functions being performed by the beak and the muscular gizzard; the esophagus, in other than owls and insectivorous species, has one or two crops, dilations where ingesta are held temporarily.

enzymatic digestion

most digestive processes in monogastric animals are enzymatic brought about by enzymes secreted into the lumen of the gastrointestinal tract and enzymes located at the brush borders of the intestinal epithelium.

digestion error

any disruption of the normal digestive process; caused by abnormal ingesta, either chemically or physically, or by an error in the physiological and biochemical processes which constitute digestion.

gastric digestion

digestion by the action of gastric juice.

impaired digestion

see maldigestion.

intestinal digestion

digestion by the action of intestinal juices, bile and pancreatic juice.

luminal phase digestion

the stage of the digestion of fats that goes on in the lumen of the intestine; as distinct from the mucosal phase that occurs in the epithelial cells.

pancreatic digestion

digestion by the action of pancreatic juice.

peptic digestion

gastric digestion by pepsin.

primary digestion

digestion occurring in the gastrointestinal tract.

ruminant digestion

characterized by the fermentative functions that are carried on in the forestomachs. Cellulose is readily digested with the output of short-chain fatty acids being the chief energy source for the animal. Nonprotein nitrogen is utilized by the ruminal bacteria for the manufacture of protein which is later available for the satisfaction of the animal's protein needs.

salivary digestion

the change of starch into maltose by the saliva; most marked in humans.

digestion tests

see starch digestion test, lactose digestion test, gelatin digestion test.