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OSSF 2 > Exam 3- The Endocrine Pancreas > Flashcards

Exam 3- The Endocrine Pancreas Flashcards

1
Q

what nerves innervate the pancreas?

A

sympathetic and parasympathetic nerves
synapse directly on pancreatic cells

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2
Q

what does the sympathetic nervous system stimulate in the pancreas?

A

glucagon release
inhibits insulin release

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3
Q

what are the functional units of the endocrine pancreas?

A

islets of langerhans

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4
Q

what mass of the pancreas does the endocrine pancreas make up and how much of the overall pancreatic blood flow does it receive?

A

2%
10%

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5
Q

what are the cell types in the islets of langerhans?

A

alpha cells
beta cells
delta cells
F cells

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6
Q

what do alpha cells secrete?

A

glucagon

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7
Q

what do delta cells secrete?

A

somatostatin

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8
Q

how do cells communicate in the islets of langerhans?

A

gap junctions
blood supply
innervation

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9
Q

what is unique about the blood supply of the islets of langerhans?

A

arteriole enters center, spreads out it network fenestrated capillaries, then converges into venules
carries insulin from beta cells to alpha and delta cells

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10
Q

what cells perform regulatory functions from inside the islets of langerhans?

A

delta cells send dendrite-like processes onto beta cells

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11
Q

what is the overall structure of insulin?

A

peptide hormone: A and B chains with connecting peptide
2 disulfide bonds between A and B chains, one more within A chain

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12
Q

what electrolyte is important for releasing insulin from the secretory granules?

A

calcium

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13
Q

what is released with insulin from the granules?

A

C-peptide in equal proportion

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14
Q

true/false: insulin activity is highly species specific

A

false

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15
Q

what is the first step of insulin synthesis?

A

translation of mRNA

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16
Q

what transporter is on beta cells that allows glucose into the cells?

A

GLUT2: facilitated diffusion

17
Q

what happens to glucose inside of the pancreatic beta cell?

A

phosporylated to glucose-6-phosphate by glucokinase

18
Q

what happens to glucose-6-phosphate inside the beta cell?

A

oxidized, producing ATP

19
Q

why is the production of ATP important for secreting insulin?

A

it closes ATP-sensitive K+ channels, decreasing conductance and leading to beta cell becoming depolarized

20
Q

what does depolarization of the beta cell lead to?

A

opening of voltage-gated Ca++ channels and increasing Ca++ concentration inside the cell

21
Q

what does increased Ca++ concentration inside the beta cell lead to?

A

Ca++ mediated exocytosis of insulin-containing granules

22
Q

is oral or intravenous glucose a stronger stimulator of insulin secretion?

A

oral glucose

23
Q

what hormones does oral glucose stimulate?

A

glucose dependent insulinotropic peptide (GIP) and glucagon-like peptide 1 (GLP-1)

24
Q

what is the structure of the insulin receptor?

A

tetramer with 2 alpha and 2 beta subunits

25
Q

what is the mechanism of action of the insulin receptor?

A

insulin binds to alpha subunits
conformational change in beta subunits: activated tyrosine kinase activity
phosphorylates other proteins and enzymes
insulin-receptor complex internalized and degraded or recycled

26
Q

does insulin bind to other places than the insulin receptor?

A

yes- in nucleus, golgi, and endoplasmic reticulum to influence gene transcription

27
Q

how does insulin decrease blood glucose?

A

increases GLUT4 transporters in cell membranes
promotes formation glycogen from glucose in muscle and liver
inhibits glycogenolysis
inhibits gluconeogenesis

28
Q

what does insulin do to blood fatty acid concentration?

A

lowers it: stimulates storage and inhibits lipolysis

29
Q

how does insulin affect blood amino acid concentration?

A

increased amino acid and protein uptake by tissues

30
Q

does insulin affect the hypothalamic satiety center?

A

yes- direct effect

31
Q

what is glucagon’s primary target?

A

liver

32
Q

what cells release glucagon?

A

alpha cells

33
Q

what is the direction of blood flow in the pancreas?

A

center to periphery
dense network fenestrated capillaries

34
Q

what percentage of the islet of langerhans do beta cells make up?

A

65%

35
Q

what do F cells secrete in the endocrine pancreas?

A

pancreatic polypeptide

36
Q

what nerves carry the sympathetic and parasympathetic innervation to the endocrine pancreas?

A

splanchnic nerves carry sympathetic (celiac ganglion)
vagus nerve carries parasympathetic

37
Q

between what cells are gap junctions in the endocrine pancreas?

A

beta cells and beta cells
alpha cells and beta cells

38
Q

what is the sequence of events for insulin synthesis?

A

translation of mRNA: preproinsulin
signal peptide cleaved: proinsulin
shuttled to endoplasmic reticulum
secretory granules in golgi
proteases cleave connected peptide

39
Q

what does exercise do to insulin secretion?

A

inhibits it: stimulates alpha-1 adrenergic receptors on beta cells: prevents hypoglycemia

OSSF 2 (19 decks)

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