Digestive Endocrinology and Glucose Metabolism Flashcards
What do duct cells in the pancreas secrete?
What do acinar cells secrete in the pancreas?
What funtions are these a part of?
NaHCO2 solution
Digestive enzymes/pancreatic enzymes
Exocrine portion of the pancreas
Where is the location of the pancreas?
Location:
- retro-peritoneum*,
- 2nd lumbar vertebral level
Extends in an oblique, transverse position
What are the parts of the pancreas?
4
head
neck
body
tail
Embryology of pancreas:
Develops from the ventral and dorsal buds.
What does the ventral bud become?2
What does the dorsal bud become? 4
Ventral bud becomes the uncinate process and inferior head of pancreas
Dorsal bud becomes superior head, neck, body and tail
What happens when the ventral bud duct does not fuse with the dorsal bud duct?
Pancreas divisum when fails to fuse
Exocrine definition?
Endocrine definition?
Exocrine: secreting outwardly via a duct
Endocrine: secreting inwardly: applied to organs and structures whose function is to secrete into the blood or the lymph a hormone that has a specific effect on another organ or part
The head of the pancreas connects to the duodenum through what?
papilla/ampulla of vater
Islets of langerhan cells secrete hormones into where?
into the blood vessels
Alpha cells secrete what?
Beta cells secrete what?
Delta cells secrete what?
F cells (Gamma) secrete what?
– glucagon
– insulin
– somatostatin
– pancreatic polypeptide
What is the main action of alpha cells?
Release Glucagon; main action to produce an increase in blood glucose
Glucogon does what?
3
What do high levels activate?
- Breakdown of glycogen
- Stimulates gluconeogenesis (inhibits glycogenesis)
- Increases transport of AA into the liver and stimulates their conversion to glucose
High levels activate adipose cell lipase making fatty acids available for use as energy
Alpha cells release glucagon into what area of circulation?
This is in response to what?
Two things stimulate this. What are they?
portal circulation
low glucose levels in the blood
- high concentrations of AA
- strenuous exercise
Metabolic Effects of Glucagon:
Glucose levels?
Amino acid levels?
Ketoacids?
increase
decrease
increase
What causes stimulation of glucagon?
6
- Hypoglycemia
- Amino acids
- Gastrointestinal hormones
- Fasting
- Exercise
- Neural influences
What are the amino acids that stimulate glucagon?
2
What are the gastrointestinal hormones that stimulate glucagon?
2
What neural influences stimulate glucagon?
2
Arginine
Alanine
Cholecystokinin (CCK)
Gastrin
- Vagal activity-acetylcholine
- Sympathetic activity-
β-adrenergic stimulation
(norepinephrine, epinephrine)
What causes inhibition of the secretion of glucagon?
7
- Glucose
- Somatostatin
3, Insulin (direct effect)
- Gastrointestinal hormones
- Free fatty acids
- Ketoacids
- Neural influences
What gastrointestinal hormones inhibit glucagon?
2
Neural influences that inhibit secretion of glucagon? 1
- Secretin
- Glucagon-like peptide-1 (GLP-1)
- α-adrenergic stimulation
DPP-4 inhibitors cause lowering of blood glucose how?
2
- stimulates insulin release
2. inhibits glucagon release
Fuel Metabolism in Anabolic states:
Hormone changes? 2
Fuel Source?
Processes involved? 3
increased insulin
decrease glucagon
Diet
Glycogen synthesis
TG Synthesis
Protein synthesis
Fuel Metabolism in Catabolic States
Hormone changes? 2
Fuel Source?
Processes involved? 4
Decrease insulin
Increase glucagon
Storage deposits
Glycogenolysis
Lipolysis
Proteolysis
Ketogenesis
Metabolic Effects of Epinephrine:
Glucose?
Free fatty acids?
Ketoacids?
Increase in all
- Glucocorticoids and GH stimulate 1 and inhibit 1 what?
2. Insulin stimulates 1 and inhibits 1 what?
- Stimulate glucose produciton
- Inhibit Glucose consumption
- Inhibits glucose produciton
- Stimulates Glucose consumption (muscle and adipose tissue)
Glucagon and Epinephrine stimulate what?
Glucose produciton in the liver
How does insulin lower blood glucose?
6
- Promoting uptake of glucose by target cells
- Provides for glucose storage as glycogen
- Prevents fat & glycogen breakdown
- Inhibits gluconeogenesis and increases protein synthesis
- Promotes fat storage by increasing transport of glucose into fat cells
- Increases triglyceride synthesis
Beta cells produce what?
pro-insulin
What is proinsulin formed by?
How does proinsulin become active insulin?
an A-chain and B-chain separated by inactive C-peptide chain
C-peptide chain is cleaved by enzymes in the beta cells and packaged in secretory granules
2/3 of glucose is stored as what in the liver?
When is insulin released back into the blood?
glycogen
Released back into the blood to keep blood glucose at steady state after intake
WHat is the main regulator of insulin?
What does glucokinase do?
What does the result of glucokinase result in?
glucose
In pancreatic beta cell glucose transporters allow influx of glucose
Results in closure of K+ channels and opening of Ca+ channels allowing secretion of insulin by exocytosis
What causes the stimulaiton of insulin?
8
- Glucose
- Amino acids
- Free fatty acids
- Keto acids
- Glucagon (direct and indirect effects)
- Gastro-intestinal hormones
- Neural influences
- Sulfonylurea drugs
Stimulation of insulin secretion:
- Types of glucose? 2
- Types of AA? 4
- Types of gastrointestinal hormones?
- Types of neural influences?
- Mannose
Galactose - Arginine
Lysine
Leucine
Alanine - Glucagon-like peptide 1 (GLP-1)
Gastric inhibitory polypeptide (GIP) - Vagal activity (acetylcholine)
β-adrenergic stimulation
What causes the inhibition of insulin?
5
- Somatostatin
- Fasting
- Exercise
- Neural influences
- Leptin
What are the neural influences that inhibit the secretion of insulin?
Sympathetic activity-
α-adrenergic stimulation (norepinephrine, epinephrine)
Insulin affects on carbohydrates:
What do carbohydrates from a meal release?
What does this stimulate?
Carbohydrates from a meal release glucose
Stimulates secretion of insulin
The secretion of insulin cause what?
Once liver has stored all the glycogen it can, insulin promotes what?
The uptake and storage of glucose in all tissue
conversion of glucose to fatty acids
Metabolic Effects of Insulin: Glucose? Free fatty acid? Ketoacids? AA?
All decrease
Insulin increases what in the muscle?
5
- ↑ GLUT4 transporters
- ↑ Glycogen
- ↑ Glycolysis (glucose –> pyruvate)
- ↑ Protein synthesis, protein degradation
- ↑ Triglycerides (FA’s from circulation)