the endocrine pancreas

Question 1

what occurs in type 1 diabetes to lead to insufficient insulin production?

Answer 1

-autoimmune destruction of beta cells

Question 2

what occurs in type 2 diabetes to lead to insufficient insulin production?

Answer 2

-insulin resistance and beta cell dysfunction

Question 3

what are some risk factors for T2DM?

Answer 3

• family history
• obesity
• pregnancy
• calorie dense diet
• sedentary lifestyle
• paternal and maternal metabolic health

Question 4

what are islets?

Answer 4

-clusters of about 1,000 endocrine cells

Question 5

what cells make up the pancreas?

Answer 5

• islets make up 1 to 2%

- remainder are mostly exocrine pancreas (which secretes digestive enzymes)

Question 6

what do alpha cells islets secrete?

Answer 6

glucagon

Question 7

what do beta cells islets secrete?

Answer 7

insulin

Question 8

what do delta cells islets secrete?

Answer 8

somatostatin

Question 9

what do PP cells islets secrete?

Answer 9

pancreatic polypeptide (PP)

Question 10

what do E cells islets secrete?

Answer 10

ghrelin

Question 11

what colours are insulin, glucagon and somatostatin under immunoflourence?

Answer 11

insulin=red
glucagon=green
somatostatin- blue

Question 12

what islets are most abundant?

Answer 12

Beta cells

Question 13

what glucose state do we want our body to be in?

Answer 13

normaglycaemia

Question 14

right after fasting/exercise (before hormones have an effect) what glucose state will the body normally be in?

Answer 14

hypoglycaemia

Question 15

right after feeding (before hormones have an effect) what glucose state will the body normally be in?

Answer 15

hyperglycaemia

Question 16

how is mature insulin synthesised from the nucleus of a pancreatic beta cell?

Answer 16

• mRNA is translated in the rough ER forming pre proinsulin
• pre proinsulin is transferred to the golgi apparatus where disulfide bridges are made between the alpha and beta chain forming proinsulin
• pro insulin is then cleaved into insulin and C peptide which are released into the plasma

Question 17

what intracellular mechanisms occur for producing insulin from when glucose enters the cell?

Answer 17

• glucose enters the cell by diffusion through GLUT 1/2
• glucose is then phosphorylated to glucokinase which can then be used in glycolysis
• glycolysis produces ATP which blocks the KATP channel
• this causes depolarisation and triggers the opening of the voltage gates Ca2+ channels
• influx of calcium triggers insulin vesicles to bind to pancreatic beta islet cell and secretion of insulin

Question 18

how would you describe the way (trend?pattern?) in which insulin is secreted?

Answer 18

biphasic

1st phase= big, quick spike in insulin to try stop hyperglycaemia

2nd phase= more controlled and usually more suited to what the person needs, this is usually a lower spike and longer

Question 19

what is an early marker for pre diabetes in terms of the phases of insulin release?

Answer 19

an early marker is the 1st phase is decreased first

Question 20

what occurs to the phases of insulin release in type 2 diabetes?

Answer 20

-normally both are decreased

Question 21

beta cells are still there when they are desensitized due to type 2 DM

True or False

Answer 21

True- they have just degranulated or dedifferentiated so no longer function

Question 22

what is the intracellular process that causes glucagon to be released in alpha cells?

Answer 22

• glucose levels drop
• glucose enters alpha cell through GLUT transporter
• glucose metabolism is low meaning there’s low levels of ATP
• due to low ATP KATP channel open only partially allowing potassium to leave the cell
• Voltage gated sodium channel allows sodium to enter the cell
• potassium leaving the cell and sodium entering the cell causes a change in the alpha cell membranes action potential
• change in action potential allows voltage gated calcium channel to open, letting calcium flow into the cell
• increase of calcium in the cell causes glucagon exocytosis

Question 23

what is the intracellular process in alpha cells to stop glucagon from getting released when there is high glucose levels in the blood?

Answer 23

• glucose enters through GLUT transporters
• glucose metabolism is high which causes lots of ATP to be produced
• ATP blocks the KATP channel, stopping potassium from leaving the cell
• blocking of KATP channel means theres not a change in membrane potential so the voltage gated sodium channel cant open
• due to glucose being greater the SGLT2 glucose transporters bring sodium ions into the cell in a non voltage manner (by diffusion)
• due to no change in action potential the calcium voltage channels remain shut meaning that calcium cannot flow in to the cell and glucagon can not be released

Question 24

what is gluconeogenesis?

Answer 24

formation of glucose from noncarbohydrate precursors such as lactate, amino acids and glycerol

Question 25

what is the relation between how much glucagon alpha cells secrete and blood glucose?

Answer 25

alpha cells secrete glucagon inversely proportional to blood glucose

Question 26

what organ does glucagon act on?

Answer 26

liver

Question 27

what effect foes somatostatin 14 (sst14) have on beta and alpha cell function?

Answer 27

it suppresses beta and alpha cell function