endocrine pancreas Flashcards
what is the endocrine portion of the pancreas made up of ?
islets of langerhans
what are the cell types in the islets of langerhans?
beta cells - insulin
alpha cells - glucagon
delta cells
what is the precursor of insulin ?
preproinsulin
cleaved into c peptide and into insulin
what gated receptor is associated with the entry of glucose into the cell ?
GLUT 2
what is the first enzyme for glycolysis ?
glucokinase
what is insulin release inhibited by?
epinephrine
due to alpha 2 receptor activation
which in turn in creases the plasma glucose levels
what type of transporter is GLUT-2 ?
bidirectional transporter
what enzyme facilitates the conversion of glucose into glucose 6 phosphate ?
glucokinase
what channels are associated with insulin release ?
voltage gated calcium channels open
what is activated once insulin is bound to insulin receptors ?
activation of tyrosine kinase domains
what is the cascade that happens upon binding of insulin to its receptor ?
tyrosine kinase activation
this leads to autophosphrylation
this leads to the activation of the PIK3 pathway
this allows for th expression of the GLUT 4 receptor
what is the function of the RAS/MAP kinase system ?
modify cell growth and gene expression
what are the insulin dependant organs ?
muscles and fats
what are the insulin independent organs ?
Brain and the RBC
use the GLUT-1
what are the effects of insulin ?
increases glycogen synthesis
inhibits glucogenesis
increases fatty acid synthesis
increases protein synthesis
what is a key side effect of insulin therapy ?
weight gain
what is hormone sensitive lipase inhibited by ?
insulin
what is hormone sensitive lipase activated by ?
glucagon and epinephrine
what is the effect of insulin on electrolytes ?
sodium retention
lowers potassium
what is the treatment for life threatening hyperkalemia ?
insulin plus glucose
what is the main stimulus for glucagon release ?
low glucose levels
how can we tell if insulin is endogenous or exogenous ?
measure c peptide levels
what does high insulin levels in the blood present as ?
presents as whipples triad
1) hypoglycemia
2) symptoms of hypoglycemia
3) worsens between meals
gets better with meals
how does glucagon increase blood glucose levels ?
by glucogenesis
what processes are increased by glucagon ?
glucogenesis
what are the processes increased by glucagon ?
glucogenesis
glycogenolysis
lipolysis
protein catabolism
how does insulin promote protein synthesis ?
allows for an anabolic state by decreasing ubiquitin mediated proteolysis
how does glucagon activate lipolysis ?
via hormone sensitive lipase
what type of protein receptor is associated with glucagon and what is the associated cascade of events ?
G protein recepto
activates adenyly cyclase
increases cAMP
activates protein kinase A PKA
where are glucagon receptors mainly found ?
mostly in the liver
what are the treatment option for a patient with hypoglycemia who is unconscious ?
IV dextrose
or intramuscular glucagon
what is the treatment for beta bloker overdose and what is the mechanism ?
glucagon
activated adenyl cyclase
raises cAMP
what is an insulinoma ?
pancreatic islet cell tumor
fasting hypoglycemia
insulin is high even when fasting
what are the symptoms of insulinoma ?
neurologic symptoms
sympathetic activation from low glucose
how is a diagnosis of insulinoma made ?
fasting insulin level is high
c peptide is elevated
proinsulin is high
what are the differentials of fasting hypoglycemia ?
exogenous insulin
oral hypoglycemics
insulinoma
what is the presentation of glucagonoma ?
glucose intolerance
presents like diabetes
what are the classic features of glucagonoma ?
necrolytic migratory erythema
genitlas buttocks and groin
what is the treatment for glucagonoma ?
somatostatin analog
what are the different MEN syndromes ?
MEN 1 - pituitary adenoma , parathyroid adenoma and pancreatic cancer
MEN 2A - parathyroid adenoma, pheochromocytoma, medullary thyroid carcinoma
MEN 2B - Marfanoid body habitus, mucosal neuroma, pheochromocytoma , medullary thyroid carcinoma
what are the gene mutations associated with each type of MEN ?
MEN 1 - MEn 1 gene mutation
MEN 2A and 2B both have RET gene mutation
what is the classic presentation associated with MEN 1 ?
patient with recurrent gastric ulcers complaining of flank pain
flank pain - calcium urolithiasis
zollinger ellison syndrome - gastrinoma
what is carney complex ?
a group of tumors
hyperpigmemtation around the mucosa
atrial myxoma
endocrine hyper secretion in the form of cushing or hyperthyroidism
influx of what type of electrolyte is associated with insulin release ?
calcium
