Proteins In Diet
The foodstuffs containing high protein content are meat, fish, egg, and milk. The proteins are also available in wheat, soybeans, oats and various types of pulses.
Table of Contents
The important items of a diet containing proteins are:
- Wheat: Glutenin and gliadin which constitute gluten
- Milk: Casein, lactalbumin, albumin, and myosin
- Egg: Albumin and vitellin
- Meat: Collagen, albumin, and myosin.
Read And Learn More: Medical Physiology Notes
The dietary proteins are formed by long chains of amino adds bound together by peptide linkages.
Digestion Of Proteins
The enzymes responsible for the digestion of proteins are called proteolytic enzymes.
- In The Mouth: Digestion of proteins does not occur in the mouth, since saliva does not contain any proteolytic enzymes. So, the digestion of proteins starts only in the stomach.
- In The Stomach: Pepsin is the only proteolytic enzyme in gastric juice. Rennin is also present in gastric juice. But it is absent in humans.
- In The Small Intestine: Most of the proteins are digested in the duodenum and jejunum by the proteolytic enzymes of the pancreatic juice and succus entericus.
- Proteolytic Enzymes in Pancreatic Juice: Pancreatic juice contains trypsin, chymotrypsin, and carboxypeptidases. Trypsin and chymotrypsin are called endopeptidases as these two enzymes break the interior bonds of the protein molecules.
- Proteolytic Enzymes in Succus Enteric us: The final digestion of the proteins is by proteolytic enzymes present in the succus entericus. It contains dipeptides, tripeptidases, and aminopeptidases.
- Final Products Of Protein Digestion: The final products of protein digestion are the amino acids which are absorbed into the blood from the intestine.
Absorption Of Proteins
- The proteins are absorbed in the form of amino acids from the small intestine. The Levo amino acids are actively absorbed by means of sodium co-transport, whereas, the dextro amino acids are absorbed by means of facilitated diffusion.
- The absorption of amino acids is faster in the duodenum and jejunum and slower in the ileum.
Metabolism Of Proteins
The metabolism of proteins is given in the form of a schematic diagram.
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