LOWRI Flashcards
What do hepatocytes do in the liver?
buffer the potential hyperglycaemic effect of a carb load
How do hepatocytes do this? (1)
storing excess glucose by converting it to glycogen = glycogenesis
How do hepatocytes do this?
excess glucose —> glycogen
excess glucose —> fatty acids
fatty acids + glycerol = triglycerides
Glycogenolysis?
the biochemical breakdown of glycogen to glucose
Gluconeogenesis?
synthesis of new glucose from non-carb sources
Renal threshold for glucose?
11.1mmol/L
Renal function in relation to glucose: type of mechanism?
passive, but Na-dependent mechanism takes place in proximal tubule
Renal function in relation to glucose: what do the tubules do with glucose?
renal tubules absorb almost all glucose, filtered by the glomeruli, urinary glucose is normally undetectable
when does glycosuria occur?
when plasma levels exceed the renal threshold
The brain is dependent on glucose, but cells cannot…
store glucose, synthesis glucose, metabolise other substances (exception of ketones), extract glucose from extracellular fluid at low glucose concentrations
Reference ranges:
Plasma / serum glucose (fasting) = 3.5-5.5mmol/L
Plasma / serum glucose (random) = <10mmol/L
Urinary glucose = negative
Islet of Langerhans?
cells that we depend on to produce the relevant hormones to maintain glucose concentration
Beta cells?
production and release of insulin
comprises >60% of islet cells
Alpha cells?
production and release of glucagon
comprises around 30% of islet cells
how many delta cells, pancreatic polypeptide cells and ghrelin-secreting cells are islet cells?
comprises around 10% of islet cells
Role of insulin?
to lower the extracellular glucose levels
stimulates glycogenolysis
inhibits gluconeogenesis, fat breakdown and protein breakdown
Insulin in the liver?
3 points
decrease glycogenolysis
decrease gluconeogenesis
decrease ketogenesis
Insulin in the muscle?
2 points
increase glucose uptake
increase ketone metabolism
Insulin in the adipose tissue?
2 points
increase glucose uptake
decrease lipolysis
Glucagon?
when is it released?
simple polypeptide chain, counter regulatory hormone, secreted in response to hypoglycaemia, does the OPPOSITE to insulin
Effect of glucagon in liver:
opposite of insulin
increase glycogenolysis
increase gluconeogenesis
increase ketogenesis
Other counter regulatory hormones:
cortisol, adrenaline, growth hormone
Diabetes mellitus? (DM)
‘an absolute or relative insulin deficiency’
either not there at all or its being produced but doesn’t work
Type 1 DM?
no insulin available, complete lack, autoimmune destruction of beta cells
Type 2 DM?
insulin available but doesn’t do its job, relative insulin resistance, chronic disorder, genetic predisposition
