Insulin and diabetes

Question 1

islets make up how much of what

Answer 1

2% mass of pancrease

Question 2

size of islets

Answer 2

~100 micro meters

Question 3

what innervation do islets receive

Answer 3

sympathetic - adrenergic

parasympatheic - cholinergic

Question 4

types of islet cells

Answer 4

• beta cells secrete insulin (60-80%)
• alpha cells secrete glucagon
• delta cells secrete somatostatin
• PP cells secrete pancreatic polypeptides

Question 5

where is glucagon secreted from

Answer 5

alpha cells of islets

Question 6

where is somatostatin secreted from

Answer 6

delta cells of islets

Question 7

where are beta cells expressed

Answer 7

core of islet

Question 8

where are alpha cells expressed

Answer 8

outside of islet / periphery

Question 9

somatostatin inhibits

Answer 9

insulin & glucagon

Question 10

insulin inhibits

Answer 10

glucagon & somatostatin

Question 11

glucagon stimulates

Answer 11

insulin and somatostatin release

Question 12

summary of insulin biosynthesis

Answer 12

nucleus: preproinsulin mRNA is transcribed
ER: preproinsulin mRNA is translated then rapidly cleaved to proinsulin
Golgi: proinulsin packaged to secretory granules
Secretory granules: proinsulin converted to insulin and c-peptide by peptidases

Question 13

proinuslin structure

Answer 13

• short a chain 21 aa
• longer b chain 30 aa
• c-peptide
  connected wih 2 disulphide bonds

Question 14

how does insulin circulate

Answer 14

mature insulin has low solubilty and forms crystals with Zn2+.
secretory granules fuse with plasma membrane and insulin then circulates blood as a monomer

Question 15

what is the precursor peptide of insulin

Answer 15

proinsulin; inactive

Question 16

basal level of insulin

Answer 16

0.4 microgram/ml in the unfed state

7mM

Question 17

half life of circulating insulin

Answer 17

~5 minutes

Question 18

where is insulin degraded

Answer 18

mostly in the liver

Question 19

autoimmune destrcution of iselt beta cells causes

Answer 19

T1DM

Question 20

what do islets show in T1DM

Answer 20

lymphocyte filatration AKA insulitus

Question 21

treatments for T1DM

Answer 21

Insulin administration,

human islet transplantation

Question 22

% of diabates cases that are T1DM

Answer 22

10%

Question 23

% of diabetes cases that are T2DM

Answer 23

90%

Question 24

pathology of T2DM

Answer 24

• insulin resistance in peripheral tissues

- beta cell dysfunction causing impaired insulin secretion

Question 25

uncommon form of diabetes

Answer 25

maturity onsent diabetes of the young - 1-2%

Question 26

common features of MODY

Answer 26

not overweight and not insulin resistance

Question 27

causes of MODY

Answer 27

single gene mutations of:
- glucokinase
- transcription factors
mutations cause beta cells defectd leading to insufficient insulin secretion and or synthesis

Question 28

treatment of MODY

Answer 28

Sulphonylureas