Which of the following is associated with maximum bile secretion?
Ans: b (Secretion of secretin) Ref: Ganong 22nd ed/p.503Secretin is a choleretic so it is associated with bile secretion Substances that increase the secretion of bile (Choleretics)SecretinBile salts (most potent stimulus)Vagal stimulationSubstances that cause contraction of gall bladder (Cholagogues) Cholecystokinin (most potent stimulus)Fatty acidsBy increasing CCK-PZ Amino acidsCCK-PZ: -Released from mucosa of jejunum (from I cells)Stimuli for secretion are presence of peptides and amino acids in small intestine and fatty acids having more than 10 carbon atoms, in the duode num.Secretes pancreatic juice rich in enzymeContracts gall bladder and release bileInhibits gastric emptying by augmenting contraction of pyloric sphincter Enhances small intestine and colonic motility Augments action of secretin in producing alkaline pancreatic juice Increases secretion of glucagon and insulinSecretin:-Released from S cells of duodenal mucosa. It is structurally similar to glucagon, GIP, VIP and GLI.Stimuli for secretion are acidity of chyme and products of protein digestionStimulates bicarbonate rich pancreatic secretion.Responsible for adding water and alkaline component to pancreatic juiceInhibits gastric acid secretion and gastric emptying by causing contraction of pyloric sphincterAugments action of CCK-PZ in producing pancreatic secretion of digestive enzymes.Stimulates bile secretion (cholerectics)Bile acids have detergent action on the lipids due to their amphipathic nature. They make the lipids soluble by forming micelles, lgm of haemoglobin yields 35 mg of bilirubin.Gastrin:-Hormone produced by G cells in the lateral wall of glands in the antral portion of gastric mucosa.Also found in pancreatic islets in fetal life, gastrinomas of pancreas and pituitary gland.Stimulates gastric acid and pepsin secretionStimulates growth of mucosa of stomach, small and large intestine.Promotes gastric emptyingStimulation of insulin secretionStimuli that increase gastrin and HC1 secretion:-Oligopeptides and amino acids in gastric lumenDistention Ca2+Epinephrine Increased vagal dischargeStimuli that decrease gastrin secretion Somatostatin Acid Secretin GIP VIPGlucagon Calcitonin
Secretion of CCK
Secretion of secretin
Secretion of gastrin
Presence of fat in food
G.I.T.