Pancreas physiology Flashcards
What is the difference between endocrine and exocrine glands?
Endocrine - secretes products directly into the blood stream (ductless gland)
Exocrine - secretes products into a duct by which it travels to its destination
What is the function of exocrine region of the pancreas?
Secretes pancreatic fluid that contains digestive enzymes that pass to the small intestine
What regulates the release of digestive exocrine hormones from the pancreas?
CCK and secretin
which are hormones secreted by the stomach and duodenum in response to distention and food
Vagus nerve to a small extent
Name the exocrine substances of the pancreas.
Amylase, lipase, proteases (tripsinogen & proteolytic enzymes activated in duodenum), HCO3- to neutralise chyme.
Describe how exocrine secretions get from their origin to their destination.
Produced in acini
Secreted into lumens of acini
Secretions accumulate in interlobular ducts
Which drain into main pancreatic ducts
Which drains into duodenum and aids digestion
What is the function of the endocrine region of the pancreas?
Secretes important hormones into the blood
Name the cells that make up islets of Langerhans.
Alpha
Beta
Delta
Gamma
What do alpha cells do?
Detect a decrease in blood glucose
So they secrete glucagon into blood
What does glucagon do?
Binds to liver receptors
Which stimulates glycogenesis (glycogen>glucose)
And production of enzymes needed for gluconeogenesis (Amino acids>glucose)
Ultimately results in increase in blood glucose!
What do beta cells do?
Detect and increase in blood glucose
So they secrete insulin into the blood
What does insulin do?
Bind to receptors on cells which changes the shape of GLUT4 channels
Which results in increased uptake of glucose by cell Increased glycogenesis (glycogen synthesis) Increased glycolysis (glucose to pyruvate)
Results in lower blood glucose
What do delta cells secrete?
Somatostatin - which regulates alpha and beta cell function
What do gamma cells secrete?
Pancreatic polypeptide - which regulates pancreatic secretion activities
Describe the blood supply to the endocrine region of the pancreas.
Very good
Most endocrine cells are in direct contact with blood vessels
Name the endocrine hormones of the pancreas.
Insulin, glucagon and somatostatin
Describe briefly how insulin is secreted. Describe the 2 phases!
Insulin is stored in the pancreas in granules. It is release when metabolic signals are received.
Beta cells release insulin in two phases
- FAST - rapid release in response to increased blood sugar
- SLOW - released slowly triggered independently of sugar
What are the main destinations of insulin?
Liver
Fat cells
Muscle cells
What does insulin do when it gets to its destination?
Insulin gets to a muscle, fat or liver cell via the blood stream
It binds with insulin receptors on the cell membrane - which triggers the cell to display GLUT4 channels on the cell membrane
GLUT4 channels allow the excess glucose to go from the blood to inside cells for storage
What is the body’s response to raised glucose?
Insulin secreted from pancreas into blood
Insulin allows glucose to be absorbed by body cells
Liver coverts glucose into glycogen
