Flashcards in Endocrine Pancreas: Insulin and Glucagon Deck (32)
The Islets of Langerhans in the pancreas contain what cell types
Alpha, Beta, Delta, F cells
Alpha cells in the islets do what?
Beta cells in the islets do what?
Delta cells in the islets do what?
F cells in the islets produce what?
Where do the alpha cells tend to be located within the islet?
The outside of the cell
Where do the beta cells tend to be located within the islet?
The inside of the cell. Delta cells tend to be in between
What does somatostatin do in the pancreas?
We know that somatostatin is an inhibitory hormone. It inhibits insulin and glucagon production in the pancreas. Works in a paracrine fashione
Proinsulin --> insulin + C peptide
B cells make highly electron dense granules
Know that insulin and C- peptide are both packaged into granules and that they are both dumped out in equal molar amounts
This can sometimes be important clinically. For example, if you have a pt who is insulin dependent but may have some residual B cell function and you want to know how much...you can measure C-Peptide level
Major stimuli for insulin secretion?
Increase in Plasma glucose
Increase in plasma amino acids
Increase in GI hormones
Increase in Parasympathetic NS (Ach)---Better absorption (insulin) when you aren't stressed
Decrease in sympathetic
Major stimuli for glucagon relase
Decrease in plasma glucose
Increase in plasma amino acids- (If you eat a steak with no bread, so high protein with no carbs, your amino acid levels will rise which will stimulate insulin release and your glucose will plummet. The release of GLucagon prevents sudden hypoglycemia
Do you see changes in peripheral glucagon levels after a big meal?
NO!!! It mostly goes to the liver.
Insulin release occurs in what pattern?
Insulin half life?
about 5 minutes
Glucagon half life?
Most of insulin degradation occurs where?
Kidney and liver
Glucagon degradation occurs where
most occurs in the liver
KNOW! Both hormones, insulin and glucagon, first go to the liver. Large amounts of each are extracted by the liver and exert their actions there. Much of these secreted hormones is also degraded by the liver so it never gets out to the rest of the body
Whereas Glucagon's major target tissue far and away is the liver, the major target tissues for insulin are:
Muscle, Liver, Adipose (three largest tissue sin the body)
KNOW: What tissues does insulin not stimulte glucose uptake
Red Blood Cells
What is the main role of glucagon
Promotes glucose release from the liver- to maintain normal plasma glucose conc
Hepatic actions of glucagon are?
Increase in amino acid uptake
Increase in gluconeogenesis
Increase in ketoneogenesis
Glucagon and catecholamines need prior action of what to function optimally in the liver?
What are some important enzymes altered by Glucagon?
-Inc in phosphorylase activity
- decrease in glycogen synthetase activity
Insulin is the most potent storage hormone
Major role of insulin>
Promotes the synthesis of each of the three main nutrient storage forms: Protein, carbs, fats
Look at the major actions of insulin