Endocrine pancreas and adrenal gland

Question 1

endocrine islets are derived from what germ layer?

Answer 1

endoderm

Question 2

islets are slightly more numerous in what part of the pancreas?

Answer 2

tail

Question 3

islets are made up of what structural components?

Answer 3

reticular fibers
rich capillary network
autonomic nerve fibers

Question 4

what cell types make up the pancreas? which is most numerous?

Answer 4

beta (most numerous) 
alpha 
delta 
G 
PP (F) 
D1 
EC

Question 5

what do beta cells secrete?

Answer 5

insulin

Question 6

what do alpha cells secrete?

Answer 6

glucagon

Question 7

what do delta cells secrete?

Answer 7

somatostatin

Question 8

what do G cells secrete?

Answer 8

gastrin

Question 9

insulin is secreted by what pancreatic cell type?

Answer 9

beta

Question 10

glucagon is secreted by what pancreatic cell type?

Answer 10

alpha

Question 11

somatostatin is secreted by what pancreatic cell type?

Answer 11

delta

Question 12

gastrin is secreted by what pancreatic cell type?

Answer 12

G cells

Question 13

what do PP (F) cells secrete? what is its function?

Answer 13

pancreatic polypeptide

inhibits exocrine secretions of pancreas

Question 14

what do D1 cells secrete? what is the function?

Answer 14

vasoactive intestinal peptide (VIP)

increases motility and stimulates GI fluid secretion

Question 15

what do EC cells secrete? what is the function?

Answer 15

secretin, motilin, substance P, serotonin

• secretin: stimulates secretion from exocrine pancreas
• motilin: promotes gastric and intestinal motility
• substance P: neurotransmitter

Question 16

proinsulin is cleaved into what products?

Answer 16

insulin and protein C

Question 17

mechanism of insulin secretion

Answer 17

• 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

Question 18

gliclazide and glimepiride are what type of drugs? what is the MOA?

Answer 18

diabetes drugs

sulfonylurea receptor inhibitors - allow membrane depolarization due to inactivation of potassium channel - calcium can enter and insulin is released

Question 19

which GLUT transporter is insulin dependent? insulin independent? which is found on beta cells?

Answer 19

insulin dependent - GLUT-4
insulin independent - GLUT-1, 2, 3, 5

GLUT-2 receptors are found on beta cells

Question 20

how does DM relate to GLUT physiology? what is the result?

Answer 20

loss of GLUT-2 from beta cell membrane and a decrease in GLUT-2 mRNA

result - impairment of glucose stimulated secretion of insulin

Question 21

the outer cortex of the adrenal gland is derived from what germ layer? what about the inner medulla?

Answer 21

outer cortex - mesoderm

inner medulla - neural crest cells of neuroectoderm

Question 22

what is required for differentiation of precursor cells into chromaffin cells?

Answer 22

cortisol and nerve growth factor

Question 23

which three arteries supply the adrenal gland?

Answer 23

• superior suprarenal (from inferior phrenic)
• middle suprarenal (from aorta)
• inferior suprarenal (from renal)

Question 24

the suprarenal arteries is responsible for supplying blood to which areas of the adrenal gland?

Answer 24

• 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

Question 25

what are chromaffin cells?

Answer 25

modified postganglionic sympathetic neurons of the adrenal medulla

Question 26

the chromaffin cells are innervated by what fibers?

Answer 26

sympathetic preganglionic fibers from T8-L1 segmental levels of the spinal cord

Question 27

with excess ACTH and cortical hypertrophy, are all three zones contributing to the hypertrophy?

Answer 27

fasciculata and reticularis glomerulosa will NOT thicken

Question 28

chromaffin cells secrete which compounds?

Answer 28

EPI (primarily) | NE

Question 29

catecholamines are derived from what amino acid?

Answer 29

tyrosine

Question 30

catechomaline biosynthesis starting at DA

Answer 30

- 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

Question 31

which catecholamine biosynthesis enzyme is regulated by cortisol?

Answer 31

phenylethanolamine N-methyltransferase (PNMT)

Question 32

phenylethanolamine N-methyltransferase (PNMT) is regulated by what compound?

Answer 32

cortisol

Question 33

what is the organ of zuckerkandl?

Answer 33

site of ectopic adrenal medullary tissue located around abdominal aorta between bifurcation and IMA

Question 34

a tumor of the organ of zuckerkandl would be expectd to chiefly increase its output of what compound?

Answer 34

NE

Question 35

congenital adrenal hyperplasia

Answer 35

- 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