The endocrine pancreas Flashcards
different islet endocrine cell types
alpha
beta
delta
pp
epsilon
what happens when blood glucose is low
beta cells turn off and insulin goes down, glucagon goes up
what happens when there is an increase in blood glucose
insulin goes up and glucagon goes down
when is the kATP channel open
at low glucose maintaining a hyperpolarised plasma membrane
when does the kATP channel close
at high glucose it depolarises the plasma membrane
what triggers insulin release
closure of kATP channel
role of sulfonylureas
bind the SUR1 subunit of the kATP channel, closing the channel and triggering insulin secretion irrespective of glucose concentrations
what else can beta cells sense other than glucose
amino acids
free fatty acids
does bet cell failure occur in both types of diabetes
yes
what does insulin drive
anabolic pathways in target tissue to promote storage of nutrients and lower blood glucose
islet defect in T2DM
impaired insulin secretion
dysregulated glucagon secretion
what do alpha cells secrete
glucagon
what does glucagon act on
the liver to promote hepatic glucose production , raising blood glucose
what does glucagonn contribute to
hyperglycaemia
what is somatostatin secreted in response to
nutrient or hormonal stimulation
what does somatostatin supress
beta and alpha cell function
what does glucagon do once released
informs body to break down triglycerides / glycogen into energy when blood glucose is low
effect of alpha cells
increase blood sugar levels
where are islet of langerhans
part of body and tail of pancreas
where does glucagon travel to
liver, adipose tissue and muscle
what does the liver convert glycogen to
glucose
what does somatostatin do
inhibits glucagon and insulin , fine tunes
how is insulin released
lucose enters beta cell via LGLUT2 transporter where it enters glycolysis and mitochondrial metabolism
Rise in ATP from glycolysis and mitochondrial metabolism
ATP binds to potassium ATP sensitive channel
Rise in ATP causes kATP to close
Closure causes depolarisation of cell membrane depolarisation causes calcium influx via voltage sensitive calcium channel- causing insulin secretion
how does glucose enter beta cell
through glut2 transporters
what specifically causes the insulin secretion
calcium influx via depolarisation of cell membrane via the katp channel to close
