glucose homeostasis Flashcards
what are the pancreas exocrine and endocrine structures and what percent do they take up
exocrine acinar cells- 98%
endocrine islet of langerhans- 2%
what do alpha cells produce
what do beta cells produce
what do delta cells produce
glucagon
insulin
somatostatin
what are gap junctions
what are tight junctions
what kind of communication between cells
junction between cells directly touching, allow small molecules to pass directly between them
small intercellular spaces
paracrine
what do the three pancreatic hormones do
insulin: increases growth and development
decreases blood glucose
glucagon: increases blood glucose
somatostatin: inhibits insulin and glucagon release
what stimulates beta cell release of insulin after increasing blood glucose ?
some amino acids, GI hormones, PNS activity stimulate B cells to release insulin
what are the effects of insulin
on proteins: increase protein synthesis
increase amino acid transport
On glucose: increase glycogenesis-> increase glycogen stores
increase glucose breakdown -> increase glycolysis
increase glucose uptake via Glut 4 proteins
On lipids: increase lipogenesis
decrease lipolysis
decreases blood glucose on the whole
what stimulates alpha cells to produce glucagon after blood glucose has decreased
Some amino acids, GI hormones, SNS and PNS
effects of glucagon
increase lipolysis-> increase gluconeogenesis
increase amino acid transport ->increase gluconeogenesis
increase hepatic glycogenlysis
increase blood glucose
How do beta cells know when to secrete insulin
they have a glut 2 transporter
glut 2 is not insulin sensitive-> very high affinity to glucose
glucose passes through cell membrane in the same prop it is in in the blood
glucose made into glucose 6 phosphate by glucokinase
glucokinases has no negative feedback reaction- so continuous conversion
ATP produced via glycolysis
closes the potassium channels- potassium remains intracellular
causes membrane depolarisation
causes calcium ion channels to open- influx of calcium
leads to release of stored insulin
what is used as a measure of insulin in the blood and why
C-peptide
as insulin is made from cleaving pro insulin to form insulin and c peptide
what is glucagon like peptide 1
what is it secreted in response to
how is it made
what does it do
a gut hormone
nutrients in the gut
Transcription product of pro-glucagon gene, mostly from L-cell
suppress glucagon
stimulate insulin
increase feeling of satiety
why does GLP-1 have a short half life?
what is GLP-1 a transcription product of?
what is it a treatment for?
Short half-life due to rapid degradation from enzyme dipeptidyl peptidase-4 (DPPG-4 inhibitor)
Transcription product of pro-glucagon gene, mostly from L-cell
diabetes
where does insulin bind to on its receptor
what does it cause a conformational change in
Insulin binds to the extracellular domain of the insulin receptor
Once insulin binds to the a-subunit, there is a conformational change in the tyrosine kinase domains of the b-subunits
