Control of digestion in human

The regulation of food intake is complex. It involves gut hormones and the enteric nervous system as well as the brain. The cells in the lining of the stomach and small intestine produce and release hormones that control the functions of the digestive system. These hormones stimulate the production of digestive juices and regulate appetite. These hormones include

• Ghrelin is produced in the stomach, and its function is to tell the brain that the body has to be fed. It increases appetite.

• Gastrin is produced in the stomach when it is stretched. It
  • Stimulates the release of gastric juice rich in pepsin and hydrochloric acid.
  • Stimulates of smooth muscle contraction in the stomach, small intestine, and large intestine, which increases gastric and intestinal motility.
  • Relaxation of the pyloric sphincter, which promotes gastric emptying into the small intestine.
  • Acidic pH levels reduce the levels of gastrin.

• Secretin is produced in the duodenum and
  • stimulates the pancreas to produce alkaline secretions (rich in bicarbonate ions)
  • slows the emptying of the stomach
  • stimulates the liver to produce bile.
• Cholecystokinin (CCK) is produced in the duodenum.
  • It reduces appetite,
  • slows down the emptying of the stomach.
  •  stimulates the release of bile from the gall bladder.

• Peptide YY (PYY) is produced in the last part of the small intestine known as the ileum as well as parts of the large intestine. It plays a role in slowing down the passage of food along the gut, which increases the efficiency of digestion and nutrient absorption after a meal and inhibits appetite.

• Glucagon-like peptide 1 (GLP-1) is produced in the small intestine and colon and has multiple actions including inhibition of gastric emptying and appetite as well as the stimulation of insulin release.
• Motilin — stimulates the production of pepsin and speeds up peristalsis.

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