Exam 3: Pancreas Flashcards
What is the most common endocrine cell type?
Beta cells
What are islets of langerhans?
Islands of endocrine cells in a sea of exocrine tissue
What cells secrete insulin?
Beta cells
What cells secrete glucagon?
Alpha cells
What does Amylin do?
Act on the CNS to suppress appetite
What does somatostatin do?
Inhibit digestive function
What does pancreatic polypeptide do?
Reduces appetite and food intake
What does Ghrelin do?
Stimulates appetite
In insulin synthesis, pro insulin is cleaved into what?
Insulin and C-peptide
What is C peptide useful for?
It is a marker of insulin production and B-cell function
Describe how Glucose triggers insulin release?
-Glucose enters via GLUT2 facilitated diffusion. Glucose reacts with PO4 to form glucose 6 phosphate. G6P forms ATP, and ATP is going to close the K channel. More K in the cell depolarizes the cell, opening Ca channels. Calcium enters the cell and triggers insulin exocytosis.
What does GLUT 1 do?
Transports glucose across the BBB
What does GLUT2 do?
Transports glucose in kidney and intestine
What does GLUT 3 do?
Transports glucose in neurons
What does GLUT4 do?
Insulin dependent transporter in most other cells of the body (adipose and resting muscle cells)
What is type 1DM?
Insulin dependent, due to lack of insulin secretion.
- Autoimmune: T lymphocytes destroy B cells
- Idiopathic or environmental cause
What is type II DM?
Tissue resistance to insulin, often the result of lifestyle choices
How can Diabetes be diagnosed with fasting plasma glucose?
- Normal: <110
- Borderline: 110-125
- Confirmed DM: >126
How can DM be diagnosed with oral glucose tolerance test?
- Ingest 75mg of glucose within 5 minutes and measure glucose at 60 and 120 minutes.
- 1 hr: < 180 is normal
- 2hr: <140 is normal
How does chronic DM result in dehydration?
Chronic hyperglycemia, so more glucose in the urine. Glucose draws more water into the urine (osmotic diuretic) and excess fluid is lost
What happens to lipid in chronic DM?
Large scale mobilization of fatty acids from TG stores. Hepatic use of fatty acids results in ketosis, which can disrupt blood pH and result in metabolic acidosis.
Respiratory ventilation may increase in an attempt to vent CO2.
Severe acidosis may depress brain function, resulting in coma and death
What happens to proteins in chronic DM?
-Lack of insulin results in a shift toward more protein catabolism. Muscle atrophy and weight loss occurs. Excess blood amino acids shift toward greater gluconeogenesis in the liver, contributing to the existing hyperglycemia
How can insulin cause hypoglycemia?
- Insulin overdose
- Reactive hypoglycemia: an extreme response to glucose, B-cells release too much insulin
If insulin excess is due to medications, what should be done?
A sugary snack will recover normal blood glucose. However if it is reactive hypoglycemia, a sugar snack can be dangerous
What two things inhibit glucagon?
High glucose and somatostatin
What 3 things stimulate glucagon?
Low glucose, epinephrine, and vagal stimulation
What is incretin (GLP1)?
A product of glucagon synthesis, it is released from intestine in response to high glucose levels in the intestine. It increases insulin release from B-cells.
What is glucagons main function?
Targets the liver to stimulate hepatic glucose output to increased plasma glucose levels
What is somatostatin stimulated by?
High fat, carbs, and protein rich meals
What is the main function of somatostatin?
Inhibit release of insulin and glucagon by hyperpolarizing the B and Alpha cells
How does epi affect blood glucose?
Increased glycogenolysis and gluconeogenesis.
Decrease insulin secretion
Increase glucagon secretion
How does cortisol affect blood glucose?
- increased gluconeogenesis
- decreased glucose uptake in tissues other than the brain
- promotes glycogenolysis in the liver in early stage fasting, and glycogen synthesis in late stage fasting
How does growth hormone affect blood sugar?
- decreased glucose uptake by muscle
- increased glucose sparing
How does growth hormone affect fatty acids?
Increase lipolysis
How does growth hormone affect amino acids?
Increase uptake into cells, decreased blood amino acids
How does growth hormone affect muscle protein?
Increase protein synthesis, decrease protein degradation, increase DNA and RNA synthesis
Where does glucose detection occur in the CNS?
Arcuate nucleus
