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Endocrine > Endocrine Pancreas (Lopez) > Flashcards

Endocrine Pancreas (Lopez) Flashcards

1
Q

major functions of the endocrine pancreas

A

regulate glucose, fatty acid, and amino acid metbaolism

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2
Q

islets of Langerhans are innervated by what?

A

adrenergic, cholinergic, and peptidergic neruons

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3
Q

what do B cells secrete of pancreas and location in islet

A

insulin and C peptide

located centrally

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4
Q

what do alpha cells of pancreas secrete and location in islet

A

glucagon

located on periphery

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5
Q

what do delta cells of the pancreas secrete and location in islet

A

somatostatin

located between alpha and beta cells

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6
Q

physical aspect of delta cells

A

neuronal appearance, send dendrite-like processes to B cells and alpha cells

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7
Q

what allows rapid communication between cells of islets

A

gap junctions

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8
Q

blood supply of islets: venous from ___ carries ___ to other 2 cells

A
  • venous blood from B cells (with insulin) goes to alpha and delta cells and baths them. can
  • blood flows first to capillaries in center of islet and picks up insulin then to periphery where is acts on alpha cells to inhibit glucagon secretion
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9
Q

beta cells negatively inhibit ___ cells to release __

A

a cells to release glucagon

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10
Q

alpha cells can positively stimulate ___ cells to secrete __ with __

A

stimulate B cells to secrete insulin with glucagon acting as positive stimulator
(regulates too much glucose being in blood from glucagon)

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11
Q

insulin synthesis

A

1) preprohormone made in ER with 4 peptides: signal sequence, A chain, B chain, C peptide
2) signal sequence cleaved and is now prohormone. Disulfide bridges from in ER (folded insulin)
3) packed into secretory vesicles in Golgi where proteases cleave off C peptide = insulin and C peptide in vesicles

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12
Q

what is used to test B cell function in type 1 diabetes mellitus patients receiving insulin injections

A

C peptide (measures endogenous insulin)

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13
Q

what receptor on the pancreatic B cell binds glucose

A

GLUT 2

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14
Q

process of insulin release

A

1) glucose binds GLUT 2 on B cell in pancreas
2) GK phosphorylates to give Glucose-6-P
3) oxidation to ATP
4) shuts off K+ ATPase
5) depolarization of the cell and opening of calcium channels
6) calcium rushes in and causes stored vesicles of insulin to be released along with C peptide

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15
Q

what drugs block the K+ ATPase on pancreatic B cell and this causes what? used for people with what

A
  • Sulfonylurea drugs (tolbutamide glyburide)
  • causes depolarization and release of insulin
  • help people with Type II DM
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16
Q

insulin secretion is done in how many phases? explain

A

2 phases

  • initial is release of preformed insulin within 5-6 minutes
  • later stage is release of newly synthesized insulin, 20-30 minutes
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17
Q

CCK and insulin. mechanism too

A

Gq, PLC—-> IP3—>Ca2+ = insulin release

—-> DAG—>PKC = insulin release

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18
Q

which molecule has the same function and mechanism of insulin release as CCK?

A

Ach

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19
Q

somatostatin mech on insulin

A

Gi which decreases cAMP and decreases insulin release

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20
Q

Glucagon and ____ mechanism on insulin

A

GLP-1,

Gs—> increased cAMP and PKA and INCREASED insulin release

21
Q

for insulin receptor tyrosine kinase autophos B subunits and itself and activates ___ which leasds to what

A

insulin receptor substrates (IRS) phos of enzymes

-either activates or inhibits these proteins to produce the metabolic actions of insulin

22
Q

insulin secretion and clearance

A

pancreas creates and releases lots of insulin which is then taken up by the liver and 80% is excreted.
-much less insulin in circulation than pancreas originally makes

23
Q

what transporter takes up glucose in the periphery and what uses this?

A

GLUT 4: liver, muscle, adipose tissue

24
Q

what cells do not use GLUT 4 for glucose uptake

A

NS, kidney tubules, intestinal mucosa, RBC, and B cells of pancreas

25
Q

insulin actions on the muscles

  • glucose uptake
  • glycogen syn
  • Hexokinase activity
  • gluconeogenesis
  • glycolysis
  • protein breakdown
  • protein synthesis
A

-increase glucose uptake w/ increased GLUT 4 transporter

  • increased glycogen synthesis
  • increased hexokinase which activates glycogen syn
-increased glycolysis: increased HK, PFK and PDH 
activity
-decreased gluconeoenesis
-increased protein synthesis
-decreased protein breakdown
26
Q

how does insulin inhibit gluconeogenesis in muscles

A

increase production of 2,6 bisphosphate which increases PFK activity and substrates directed away from formation of glucose

27
Q

insulin effects on triglyceride and FA metabolism in adipose tissue

  • HSL
  • lipoprotein lipase
  • triglyceride formation
  • triglyceride breakdown
  • FA uptake
  • FA release
  • glucose uptake
A
  • inhibits HSL (stops lipolysis)
  • increases lipoprotein lipase activity (breaksdown chylomicrons and triglycerides so they can be stored later as triglycerides in adipose tissue)
  • triglyceride formation increases
  • triglyceride breakdown decreases
  • FA uptake increases
  • FA release decreses
  • Glucose uptake increases
    • becomes a-glycerol-P + FA = triglyceride
28
Q

insulin decreases what in the blood

A

ketoacids (not enough FA available)
blood glucose
amino acids
FA

29
Q

what enzyme in the liver is inactivated by insulin to prevent glycogenolysis

A

liver phosphorylase

30
Q

insulin actions in the liver:

__ glycogen synthesis
___ glucose release and ___ gluconeogenesis
___ glucose-6-phosphatase
___ glycolysis
___ acetyl coA, ___ FA synthesis
___ triglyceride storage and export (VLDLs)
___ protein syn, ___ protein degradation

A

increase glycogen syn
decrease glucose release and decrease gluconeogen
decrease glucose-6 phosphatase
increase glycolysis
increase acetyl coA and FA synthesis (sent to adipose tissue in VLDLs)
increase TGs storage
increase protein syn, decrease protein degradation

31
Q

insulin actions in adipose tissue:

\_\_ GLUT 4
\_\_\_glycolysis
   \_\_\_a-glycerol phosphate
    \_\_\_ acetyl coA, and FA syn
\_\_\_ TGs
\_\_\_\_ HSL
\_\_\_ LPL
A 
increase GLUT 4
increase glycolysis
increase a-glycerol phosphate 
increase acetyl CoA and FA syn
increase TGs
decrease HSL
increase LPL
32
Q

insulin causes K+ to do what in the cells

A

be taken up by the cells and decrease K+ blood levels

-activates Na+/K+ ATPase

33
Q

what inhibits insulin secretion

A 
fasting
decreased blood glucose
exercise
somatostatin
a-adrenergic agonists (actiate Gi)
Diazoxide
34
Q

what stimulates insulin secretion

A 
increased glucose, aa, FA, and ketoacids
glucagon
cortisol
GIP
ACh
increased Blood K+
sulfonylurea drugs
Obesity
35
Q

diabetes mellitus type 1 __ conversion of FA to ketoacids and ___ ketoacid utilization by tissues

A

increases and decreases

36
Q

3 causes for obesity-induced insulin resistance

A

1) decreased GLUT-4 uptake of glucose in response to insulin release
2) decreased ability of insulin to repress hepatic glucose production
3) inability of insulin to repress HSL and increase LPL

37
Q

pathophysiology of DM type II

A

middle aged or older
increased hepatic glucose production
hyperglucagonemia (no insulin to down reg glucagon)
not as prone to ketoacidosis (some insulin appears to protect from development)

38
Q

why is hyperglucagonemia occuring in DM II

A

no insulin can get in the cells and down regulate glucagon release

39
Q

how can DM II occur in non obese patients

A

decrease in insulin release by pancreas

varying degrees of insulin resistance can also occur

40
Q

glucagon is a family of peptide that includes what

A

secretin and GIP

41
Q

what stimulates glucagon release

A 
decreased blood glucose **
increased aa (arginine and alanine)

Fasting
CCK
Ach
B-adrenergic agonists

free CAB

42
Q

what inhibits glucagon release

A

insulin
somatostatin
increased FA
increased ketoacid concentration

43
Q

glucagon increases what in the blood

A

FA, glucose, and ketoacids

44
Q

how does glucagon increase blood glucose (mech)

A

glucagon increases cAMP which activates PKA which decreases production of Fructose 2,6 BP—> increased gluconeogenesis

-also increases glucogenolysis and inhibtis glycogen formation from glucose

45
Q

glucagon __ lipolysis and inhibits ___ which shunts substrates toward gluconeogenesis

A

increases and inhibits FA syn

46
Q

what are produced from FA

A

ketoacids

47
Q

incretin hormones?
what does it do to insulin and gastric emptying
-glucagon secretion?
responds to what?

A

GLP, GIP

  • secreted in response to GI glucose and fat
  • stimulate insulin secretion
  • inhibit glucagon secretion
  • slow gastric emptying
48
Q

in insulin resistance: the ability of insulin to suppress ___ in adipose tissue and ___ secretion by alpha cells in the islet results in leads to __ in gluconeogenesis when defective

A

lipolysis, glucagon, increased gluconeogenesis

Endocrine (14 decks)

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