Glucose Regulation Flashcards
Where are glucagon receptors mainly expressed?
- in liver and kidney
Which cell types have insulin receptors (that are focused on for this course)?
- liver, muscle and adipose
- plus insulin regulates self in pancreas
How is blood glucose under control? Why is it controlled?
- under extremely tight control
- because glucose main energy source for cells to use
How does insulin and how does glucagon affect blood glucose?
- insulin decreases blood glucose
- glucagon increases blood glucose
When do pancreatic hormones work together?
- to regulate blood glucose after meals and in between meals
What hormones are from the pancreatic islets? What are the other two important blood glucose regulation hormones?
- insulin, glucagon, somatostatin
- glucagon-like peptide-I and gastric inhibitory peptide (aka glucose-dependent insulinotropic peptide)
What are glucagon-like peptide-I and gastric inhibitory peptide? What is their function?
- both incretins
- proteins that amplify insulin effects and are secreted by cells of the small intestine
What cells does the pancreas contain?
- islets of langerhans
- B cells: insulin (center)
- A cells: glucagon (periphery)
- D cells: somatostatin (periphery)
How is insulin involved in paracrine feedback?
- activates beta cells (insulin producers) and inhibits alpha cells (glucagon producers)
How is glucagon involved in paracrine feedback?
- activates alpha cells, activates beta cells, activates delta cells
How is somatostatin involved in paracrine feedback?
- inhibits alpha cells, inhibits beta cells
Where is GLP-I made and why is this interesting?
- made in intestine
- same precursor as glucagon but very different function!
How is GLP-I involved in paracrine feedback?
- acts on pancreas as potent stimulator insulin transcription and release after meals
- decreases secretion glucagon
- acts on other tissues as well as pancreas
How is GIP involved in paracrine feedback?
- amplifies insulin effects
- secreted by cells of the small intestine
What is hypoglycemia? What are the symptoms?
- if blood suar levels drop too low
- potentially fatal
- loss of consciousness, brain damage, lethal coma
What is hyperglycemia? What are the symptoms?
- short term: appetite suppressed
- long-term: chronic health problems associated with diabetes mellitus (eye, kidney, heat disease, nerve damage)
What is diabetes mellitus? What are the two types?
- deficiency in secretion or action of insulin
- Type I: no insulin
- Type II: insulin resistant
How is type I diabetes mellitus treated?
- used to use pork and beef but more expensive and unsafe
- now human insulin made in host bacteria factory
Cell surface receptors control gene expression by which pathways?
- MAPK, PKC, PI3K
How does phosphorylation occur and what does it result in?
- occurs in a chain reaction
- activates transcription factors that bind DNA and activate or repress transcription of genes into proteins
What pathways stimulate insulin secretion?
- calcium at voltage-gated calcium channel (VGCC)
- GLP-1 acting on GPCR
What pathway stumulates insulin synthesis?
- insulin at redeptor tyrosine kinase plus glucose sensor that transports glucose into cell
How long does it take to synthesize insulin?
- takes >1hr
- insulin stored for immediate release in response to food
What is required to release insulin?
- calcium (from mitochondria and voltage gated calcium channel stimulated by glucose)
