Pathophysiology of diabetes Flashcards
(31 cards)
What is the healthy range of plasma glucose levels?
3.5 - 8 mmol/L
How does insulin change the behaviour of GLUT 4?
Insulin binds to tyrosine kinase receptors on the cell surface, which causes migration of GLUT 4 from the cytoplasm to the membrane, allowing glucose uptake
What are the 3 substrates of gluconeogenesis?
Lactate
Glycerol
Amino acids
In what way does insulin affect plasma glucose levels?
Decreases plasma glucose levels
In what way does glucagon affect plasma glucose levels?
Increases plasma glucose levels
Proinsulin is cleaved into what?
Insulin + C-peptides
How can the amount of endogenous insulin be measured?
Measuring the level of C-peptides
Which cells in the pancreas secrete insulin?
Beta cells
Which cells in the pancreas secrete glucagon?
Alpha cells
Which cells in the pancreas secrete somatostatin?
Delta cells
Does GLUT 2 have a high or low affinity for glucose?
Low
Describe how glucose triggers the release of insulin from beta cells.
Glucose enters the beta cells via GLUT 2.
Inside the cell, glucose is phosphorylated by glucokinase to form glucose-6-phosphate.
Glucose-6-phosphate is oxidised to form ATP.
ATP closes K+ channels, causing depolarisation of the cell.
Depolarisation triggers the opening of voltage-gated Ca2+ channels, allowing an influx of calcium into the cell.
Ca2+ influx stimulates fusion of insulin-containing vesicles with the membrane and exocytosis of insulin.
Insulin leaves the beta cells via what mechanism?
Exocytosis
What is the incretin effect?
The increased insulin secretion observed when glucose is taken orally rather than intravenously - due to incretin hormones
Is insulin catabolic or anabolic?
What does this mean?
Anabolic
It builds and stores energy, rather than breaking it down
What effect does insulin have on liver phosphorylase?
What effect does this have?
Inhibits liver phosphorylase
Promotes glucose storage in the liver
What effect does insulin have on glucokinase?
What effect does this have?
Activated glucokinase
Promotes glucose storage in the liver
What does insulin activate to promote glycogen synthesis?
Glycogen synthase
What effect does insulin have on fatty acid synthesis?
Increases fatty acid synthesis
What effect does insulin have on fat storage in adipose tissue?
Increases fat storage
What effect does insulin have on protein synthesis?
Promotes protein synthesis / inhibits protein breakdown
Which 2 processes does glucagon stimulate?
Gluconeogenesis
Glycogenolysis
How does glucagon increase free fatty acid production?
Activates adipose cell lipase
What is the effect of somatostatin on insulin secretion?
…on glucagon?
Inhibits both insulin + glucagon
