Henry Family Blog

There are four phases of digestion; interdigestive, dephalic, gastric and intestinal.  Interdigestion: The digestive tract is quiet.  The low pH in the stomach inhibits gastrin secretion and stimulates somatostatin secretion.  Sematostatin inhibits gastrin and HCl secretion.  Gastrin stimulates the production of HCl.

Cephalic refers to the sight, smell and taste of food activating the vagal efferents.  Ach stimulates secretion of HCl, pepsinogen, gastrin, and of pancreatic enzymes.  There is inhibition of somatostatin and some pancreatic juice enters the jejunum.

Gastric digestion is the stomach working.  It has the highest acid secretion and the highest plasma gastrin.  Peptides and amino acids stimulate gastrin secretion.  Partially digested food acts as a good buffer.  The entry of food stimulates mechano- and chemoreceptors in the stomach wall.  Vagus and enteric nervous system active.  Enteric causes peristalsis.

Intestinal: amino acids, peptides and digested fats stimulate the release of CCK which slows the entry of the chyme, stimulates pancreatic juice and bite release.  The gastric inhibitory peptide decreases stomach secretions, motility and emptying.  As food leaves the stomach, less buffers are available which makes the pH decrease.  Gastrin is inhibited and somatostatin increases.  The low pH stimulates the secretion of secretin which stimulates the flow of pancreatic juice and inhibits the secretion of gastric juice.  Secretion and CCK enhance the secretion of digestive enzymes from the pancreas and bite salts from the gall bladder.  Digested foods feedback into the stomach and inhibits gastric acid production.

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