Endocrine pancreas and adrenal gland Flashcards
endocrine islets are derived from what germ layer?
endoderm
islets are slightly more numerous in what part of the pancreas?
tail
islets are made up of what structural components?
reticular fibers
rich capillary network
autonomic nerve fibers
what cell types make up the pancreas? which is most numerous?
beta (most numerous) alpha delta G PP (F) D1 EC
what do beta cells secrete?
insulin
what do alpha cells secrete?
glucagon
what do delta cells secrete?
somatostatin
what do G cells secrete?
gastrin
insulin is secreted by what pancreatic cell type?
beta
glucagon is secreted by what pancreatic cell type?
alpha
somatostatin is secreted by what pancreatic cell type?
delta
gastrin is secreted by what pancreatic cell type?
G cells
what do PP (F) cells secrete? what is its function?
pancreatic polypeptide
inhibits exocrine secretions of pancreas
what do D1 cells secrete? what is the function?
vasoactive intestinal peptide (VIP)
increases motility and stimulates GI fluid secretion
what do EC cells secrete? what is the function?
secretin, motilin, substance P, serotonin
- secretin: stimulates secretion from exocrine pancreas
- motilin: promotes gastric and intestinal motility
- substance P: neurotransmitter
proinsulin is cleaved into what products?
insulin and protein C
mechanism of insulin secretion
- proinsulin packaged into immature, clathrin coated vesicles by trans-Golgi face
- immature vesicles are slightly acidic and enzymatic cleavage of proinsulin is facilitated
- mature vesicles as clathrin coat is shed - these vesicles become acidic
gliclazide and glimepiride are what type of drugs? what is the MOA?
diabetes drugs
sulfonylurea receptor inhibitors - allow membrane depolarization due to inactivation of potassium channel - calcium can enter and insulin is released
which GLUT transporter is insulin dependent? insulin independent? which is found on beta cells?
insulin dependent - GLUT-4
insulin independent - GLUT-1, 2, 3, 5
GLUT-2 receptors are found on beta cells
how does DM relate to GLUT physiology? what is the result?
loss of GLUT-2 from beta cell membrane and a decrease in GLUT-2 mRNA
result - impairment of glucose stimulated secretion of insulin
the outer cortex of the adrenal gland is derived from what germ layer? what about the inner medulla?
outer cortex - mesoderm
inner medulla - neural crest cells of neuroectoderm
what is required for differentiation of precursor cells into chromaffin cells?
cortisol and nerve growth factor
which three arteries supply the adrenal gland?
- superior suprarenal (from inferior phrenic)
- middle suprarenal (from aorta)
- inferior suprarenal (from renal)
the suprarenal arteries is responsible for supplying blood to which areas of the adrenal gland?
- cortical arteries supply cortical parenchyma and form venous plexus which then supplies the medulla
- medullary arteries penetrate the cortex (do not supply it) and supply medullary parenchyma
what are chromaffin cells?
modified postganglionic sympathetic neurons of the adrenal medulla
the chromaffin cells are innervated by what fibers?
sympathetic preganglionic fibers from T8-L1 segmental levels of the spinal cord
with excess ACTH and cortical hypertrophy, are all three zones contributing to the hypertrophy?
fasciculata and reticularis
glomerulosa will NOT thicken
chromaffin cells secrete which compounds?
EPI (primarily)
NE
catecholamines are derived from what amino acid?
tyrosine
catechomaline biosynthesis starting at DA
- dopamine translocated into secretory granule
- dopamine beta-hydroxylase converts DA to NE
- NE transported out of secretory granule into cytoplasm
- phenylethanolamine N-methyltransferase (PNMT) converts NE to EPI
which catecholamine biosynthesis enzyme is regulated by cortisol?
phenylethanolamine N-methyltransferase (PNMT)
phenylethanolamine N-methyltransferase (PNMT) is regulated by what compound?
cortisol
what is the organ of zuckerkandl?
site of ectopic adrenal medullary tissue located around abdominal aorta between bifurcation and IMA
a tumor of the organ of zuckerkandl would be expectd to chiefly increase its output of what compound?
NE
congenital adrenal hyperplasia
- pathway to cortisol production is dysfunctional
- steroid production is shunted to androgens
low cortisol causes excessive ACTH production and influence - leads to hypertrophy of inner cortex (inner two zones) - more androgens
leads to ambiguous genitalia in a female
