PANCREASAHMAD AMINUDDIN

CELL TYPES IN THE PANCREATIC ISLETSALPPHA or A CELLS : - 17 % of pancreatic islet cells. - secrete GLUCAGON.BETA or B CELLS : - 70 % of pancreatic islet cells. - secrete INSULIN.DELTA or D CELLS : - 7 % of pancreatic islet cells.F CELLS : - 6 % of pancreatic islet cells. - secrete PANCREATIC POLYPEPTIDE.

INSULIN SECRETION IS ALSO STIMULATED BYACETYLCHOLIN - from CN X that inervate the pancreatic islets.ARGININ AND LEUCINE - which woud be present in the blood at higher levels after a protein-containing meal.GLUCOSE-DEPENDENT INSULINOTROPIC PEPTIDE - a hormone realised by enteroendocrine cells of the small intestine in response to the presence of glucose in the gastrointestinal tract.

GLUCAGON SECRETION IS STIMULATED BYINCREASED ACTIVITY OF THE SYMPATHETIC DIVISION OF THE ANS, AS OCCUR DURING EXERCISE.A RISE IN BLOOD AMINO ACIDS IF BLOOD GLUCOSE LEVEL IS LOW, WHICH COULD OCCUR AFTER A MEAL THAT CONTAINED MAINLY PROTEIN.

GLUCAGONCONTROL OF SECRETION - Decreased blood level of glucose. - Exercise and mainly protein meal stimulate secretion. - Somatostatin and insulin inhibit secretionPRINCIPAL ACTIONS

GLUCAGONPRINCIPAL ACTIONS - Raises blood glucose level by accelera- ting break down of glycogen into glucose in liver. - Converting other nutriens into glucose in liver ( gluconeogenesis ). - Releasing glucose into the blood.

INSULINCONTROL OF SECRETION - Increased blood level of glucose. - Acetylcholine ( released by parasympa- thetic vagus nerve fibers ). - Arginine and leucine ( two aminoacids ). - Glucagon, GIP, Hgh and ACTH stimulate secretion. - Somatostatin inhibits secretion.

INSULINPRINCIPAL ACTIONS - lowers blood glucose level by accelera- ting transport of glucose into cells. - Converting glucose into glycogen ( glyco genesis ). - Decreasing glycogenolysis and gluconeo- genesis ). - Increases lipogenesis and stimulates protein synthesis.

SOMATOSTATINCONTOL OF SECRETION - Pancreatic polypeptide inhibits secretion.PRINCIPAL ACTIONS - Inhibits secretion of insulin and glucagon and slows absorption of nutrients from the gastrointestinal tract.

PANCREATIC POLYPEPTIDECONTROL OF SECRETION - Meals containing protein, fasting, exercise and acut hypoglycemia stimulate secretion. - Somatostatin and elevated blood glucose level inhibit secretion.PRINCIPAL ACTIONS - Inhibits somatostatin secretion, gallbladder secretion and secrertion of pancreatic digestive enzymes.