Energie

Question 1

what are the hormones regulating blood glucose and which one decreasesBG?

Answer 1

insulin
glucagon
epinephrine
cortisol
GH
TH
secretin
cholecystokinin
=> only insulin decreases BG

Question 2

What are the different types of cells of Islet of Langerhans and what do they secrete?

Answer 2

a-cells = glucagon
b-cells = insulin
D-cells = somatostatin
E-cells = grehlin (not in all)
F-cells  = pancreatic PP

Question 3

what are the effects of somatostatin?

Answer 3

inhibits glucagon, insulin, PP, increase or decrease neurons signal, inhibits D-cells (-ve feedback) and many GI hormones

Question 4

what stimulates insulin secretion?

Answer 4

• BG increase
• GI hormones increase
• parasympathetic stimulation
• blood AA increase

Question 5

what decreases insulin secretion?

Answer 5

sympathetic stimulation

epinephrine

Question 6

what are the steps of insulin release from B-cells?

Answer 6

1. glucose linked to GLUT2 = in cells
2. aerobic glycolysis => increases ratio of ATP/ADP
3. inhibits K+ channels = blocks K+ efflux
4. depolarization of the membrane
5. Opening of Ca channels = Ca++ enters b-cells
6. exocytosis of insulin in granules
7. Opening of K/Ca channels = repolarization
8. glucose metabolism = factors facilitate exocytosis and proinsulin synthesis
9. GLP-1 = cAMP = increases ion channels + exocytosis

Question 7

What is the neural anticipation of glucose metabolism?

Answer 7

a slight increase in glucagon to stimulate insulin secretion before glucose is ingested

Question 8

what are the glucose receptors and where are they situated?

Answer 8

GLUT2 = pancreas b-cells, liver, SI, kidney 
GLUT3 = brain, placenta, kidney
GLUT4 = muscle, heart, adipose tissues, others

Question 9

how does glucose uptake is regulated by insulin?

Answer 9

insulin = RTK pathway = exocytosis of glut4 receptors
insulin activates glucokinase = glucose into glu 6-p = maintains a low intracellular concentration of glucose = glucose enters

Question 10

What defects can cause insulin resistance?

Answer 10

• pre-receptor
  = autoantibodies against insulin
  = mutant insulin
• receptors
  = decreased # and affinity
• post-receptor
  = deficient signals
  = low glut4 expression

Question 11

What are the steps leading to T2DM in obese pts?

Answer 11

1. visceral fat from adipose tissues accumulation = increases FFAs in circulation
2. pro-inflammatory adipokines = inflammation
3. FAs into liver = converted into TGs
4. tgs utilized by muscles = increased fat into muscles and later myosteatosis
5. impaired glu uptake and utilization by mucles
6. increased glu in circulation
7. dyslipidemia + hyperglycemia
8. overstimulation of b-cells (hyperinsulinemia at beginning) and destruction
9. T2DM

Question 12

What are pancreatic polypeptides?

Answer 12

• produced by F-cells of Islet of Langerhans
• decrease appetite
• increased secretion after a meal (by vagus nerve and cholecystokinin)
• inhibit bile acid secretion from blocking gallbladder contraction
• inhibit digestive enzymes

Question 13

what do GI hormones regulate into the nervous system?

Answer 13

appetite and gut motility

Question 14

what do GI hormones regulate in pancreas?

Answer 14

insulin or glucagon stimulation

=> postprandial BG

Question 15

what is the vagus nerve?

Answer 15

the longest nerve of NS
motor and sensory
controls appetite, digestion and metabo
releases acetylcholine = insulin release