photo.jpg

## 3. Secretin - contains 27 amino acids - is homologous to glucagon; 14 of the 27 amino acids in secretin are the same as those in glucagon - All of the amino acids are required for biologic activity. ### a. Actions of secretin - are coordinated to reduce the amount of H+ in the lumen of the sma...

## 3. Secretin - contains 27 amino acids - is homologous to glucagon; 14 of the 27 amino acids in secretin are the same as those in glucagon - All of the amino acids are required for biologic activity. ### a. Actions of secretin - are coordinated to reduce the amount of H+ in the lumen of the small intestine. - stimulates pancreatic HCO3- secretion and increases growth of the exocrine pancreas. - Pancreatic HCO3- neutralizes H+ in the intestinal lumen. - stimulates HCO3- and H₂O secretion by the liver and increases bile production. - inhibits H+ secretion by gastric parietal cells. ### b. Stimuli for the release of secretin - Secretin is released by the S cells of the duodenum in response to: - H+ in the lumen of the duodenum. - fatty acids in the lumen of the duodenum. ## 4. GIP = Glucose-dependent insulintropic peptide (GIP) - Contains 42 amino acids. - Is homologous to secretin and glucagon. ### a. Actions of GIP C. Neurocrine - are synergistic or additive, and - release other neurotransmitters which are not always the same as those in the neurocrine. - Neurotransmitters include: - The neurotransmitter GRP - VIP - Substance P - Bombesin - -