The Endocrine Pancreas Flashcards
What does SGLT1 do?
Glucose absorption from gut
What transporters are responsible for glucose reabsorption from the kidney?
SGLT1 and 2
Where are GLUT4 receptors found?
Muscle and adipose tissue
Which of the GLUT transporters are insulin dependant?
GLUT4
What does the affinity of a transporter relate to?
Rate at which glucose moves down the concentration gradient
What does a high/low transporter affinity mean?
Constant movement (high), changeable movement (low)
What are the islets of langerhans?
Clusters of endocrine cells surrounded by the exocrine pancreas
What do the alpha, beta and delta cells in the islets of langerhans secrete?
Alpha = glucagon Beta = insulin Delta = somatostatin
Why is C peptide useful?
Metabolically inert so a good marker for if there’s insulin or not
What vessels supply the pancreas?
Branches of the coeliac, superior mesenteric and splenic arteries
Where do the pancreatic veins drain into?
Portal system
What stimulates insulin secretion?
Plasma glucose, amino acids, glucagon, incretin hormones and PNS
What inhibits insulin secretion?
Somatostatin and alpha adrenergic
What inhibits glucagon secretion?
Plasma glucose and somatostatin
What stimulates glucagon secretion?
Amino acids, beta adrenergic and PNS
How can ACh cause an increase in intracellular [calcium]?
Phospholipase C pathway -> increase in insulin secretion
How can adenylate cyclase increase insulin secretion?
cAMP -> PKA which increase the effect of calcium on the granule exocytosis
What inhibits adenylate cyclase?
Adrenaline
What type of receptors are glucagon and insulin?
Glucagon = GPCR Insulin = tyrosine kinase
What happens when insulin binds to its receptor?
- Translocation of GLUT4 transporter to plasma membrane -> influx of glucose
- glycogen synthesis
- glycolysis
- fatty acid synthesis
- metabolic enzyme activity modulation (gene transcription regulation)
What is the insulin receptor made up of?
Tetrameric- 2 alpha subunits on surface and 2 beta which span the membrane and are bound to IRS proteins
What does IRS stand for?
Insulin receptor substrate
What is acetyl CoA carboxylase inhibited by?
PKA
What are most glucagon actions mediated by?
Adenylate cyclase or production of cAMP -> pKa
