The Pancreas and Release of Insulin Flashcards
What are beta cells?
Cells found in the islets of Langerhans that secrete the hormone insulin
What is glucagon?
A hormone that causes an increase in blood glucose concentration
What is insulin?
The hormone, released from the pancreas, that causes blood glucose levels to go down.
Where is the pancreas situated in the body?
Just below the stomach
What are the two main secretions of the pancreas?
Pancreatic juices containing enzymes which are secreted into the small intestine.
Hormones which are secreted from the islets of Langerhans into the blood.
How do exocrine glands secrete substances?
Into a duct.
What is the exocrine function of the pancreas?
The synthesis and release of digestive enzymes.
Describe the placements of the exocrine cells.
The exocrine cells are in small groups surrounding each tiny tubules. Each group of cells is call acinus (plural acini)
How are the acini grouped?
They are grouped together into small lobules separated by connective tissue.
Where do the cells of the acini secrete the enzymes they synthesise?
Into the tubule at the centre of the group.
What do the tubules of the acini join up to form?
Intralobular ducts that eventually combine to form the pancreatic duct.
What does the pancreatic duct do?
Carries the fluid containing the enzymes into the first part of the small intestine (duodenum)
What enzymes does the fluid in the pancreatic duct contain?
Pancreatic amylase
Trypsinogen
Lipase
What does pancreatic amylase do?
It is a carbohydrase that converts amylose to maltose.
What is Trypsinogen?
It is an inactive protease which will be converted to the active form trypsin when it enters the duodenum.
What does lipase do?
Digests lipid molecules.
Why is hydrogen carbonate found in the pancreatic fluid?
Provides optimal pH for digestive enzymes
What do alpha cells secrete?
Glucagon
What do the islets of Langerhans contain?
Alpha and beta cells
What does insulin do?
The action of insulin by: attaching to receptors on the surfaces of target cells. controlling the uptake of glucose by regulating the inclusion of channel proteins in the surface membranes of target cells. activating enzymes involved in the conversion of glucose to glycogen.
What channels do the beta cells contain and why?
K(ATP) channels, as they are involved in insulin secretion
At rest what is the potential difference of a beta cell membrane?
-70mV
Which enzyme converts glucose into an immediate supply of ATP?
Hexokinase
