Endocrinology 3
Endocrine pancreas-regulation of blood glucose concentration
Exocrine pancreas- produces a range of proteases and lipases essential for digestion
Beta cell- insulin
Inhibits glucagon
Alpha cell-glucagon
Stored in granules in the cyctoplasm
Released from the cell by exocytosis
Raises blood glucose levels
L-arginine potent stimulator of glucogon release
Promotes insulin and somatostatin release
Delta cell-somatostatin
Inhibits insulin, glucagon and pancreatic polypeptide
Secreted in a fed state
Inhibits gastric acid secretion, contraction of the gall bladder and reduces intestinal
motility and absorption
Slow nutrient absorption- delay an increase in blood glucose
Gamma cells-pancreatic polypeptide
Blood supply to the islet:
Afferent arterioles of the pancreatic duodenal arteries
Innervation-vagus nerve -parasympathetic
Greater and middle splanchnic nerves- sympathetic
Insulin: 51 amino acids
2 chains held together by disulphide bonds
Liver=major site for insulin inactivation
Insulin rapidly removed from the circulation
Inactivated by degradation
C peptide
A chain
B chain
Becomes cleaved
A and b chain= active
C-peptide alone
How is insulin secretion stimulated:
Increased blood glucose- induces insulin exocytosis
Incretins- Regulate the amount of insulin that is secreted after eating.
Endocrine pancreas-regulation of blood glucose concentration
Exocrine pancreas- produces a range of proteases and lipases essential for digestion
Beta cell- insulin
Inhibits glucagon
Alpha cell-glucagon
Stored in granules in the cyctoplasm
Released from the cell by exocytosis
Raises blood glucose levels
L-arginine potent stimulator of glucogon release
Promotes insulin and somatostatin release
Delta cell-somatostatin
Inhibits insulin, glucagon and pancreatic polypeptide
Secreted in a fed state
Inhibits gastric acid secretion, contraction of the gall bladder and reduces intestinal
motility and absorption
Slow nutrient absorption- delay an increase in blood glucose
Gamma cells-pancreatic polypeptide
Blood supply to the islet:
Afferent arterioles of the pancreatic duodenal arteries
Innervation-vagus nerve -parasympathetic
Greater and middle splanchnic nerves- sympathetic
Insulin: 51 amino acids
2 chains held together by disulphide bonds
Liver=major site for insulin inactivation
Insulin rapidly removed from the circulation
Inactivated by degradation
C peptide
A chain
B chain
Becomes cleaved
A and b chain= active
C-peptide alone
How is insulin secretion stimulated:
Increased blood glucose- induces insulin exocytosis
Incretins- Regulate the amount of insulin that is secreted after eating.
