Acute regulation of glucose

Question 1

after a meal what level can portal glucose increase to

Answer 1

20 mM

Question 2

what types of cells secrete glucagon and insulin

Answer 2

insulin B cells in the islets of lengerhams

glucagon alpha cells

Question 3

describe the structure of islets of langerhams between b and a cells

Answer 3

b cells mainly central and most abundant

a cells at the periphery

Question 4

what are the third type of cells in the islet of langerham

Answer 4

delta which produce somatostatin and a few f cells which produce pancreatic polypeptide

Question 5

how do b cells produce insulin

Answer 5

sense glucose and aa in the blood by using it to make ATP
entry of glucose via glut2 is insulin sensitive and low affinity
atp closes Katp channels depolarising the membrane
Ca influx and CICR induce exocytosis of insulin

Question 6

which method of ingesting glucose causes biggest change in insulin

Answer 6

oral rather than iv produces more insulin

Question 7

describe how the nervous system affects insulin production

Answer 7

PNS drives and SNS inhibits secretion

Question 8

how do incretins affect insulin

Answer 8

act via cAMP to increases exocytosis

Question 9

describe the packaging and release of insulin

Answer 9

preprohormone from cells and cleaved to pro hormone
internal disulphide bonds fold up
cleaved in golgi to make A and B chains which are linked
C chain used as biomarker

Question 10

describe the insulin receptor structure

Answer 10

a receptor tyrosine kinase - the receptor itself is an enzyme
the TK domains phosphorylate each other and nearby proteins in particular a family of insulin receptor substrates

Question 11

what are the two main pathways of insulin receptor signalling and what are they both mediated by

Answer 11

PI3K and PKB pohorylate proteins altering activity (and inserting GLUT4)

MAPK pathway alters gene expression

both mediated by insulin receptor substrates

Question 12

what are the effects of insulin on the liver

Answer 12

glycogen storage and VLDL production increase while gluconeogenesis and ketone body production are inhibited
there is no GLUT4 in the liver

Question 13

what are the effects of insulin on the muscle

Answer 13

GLUT4 inserted and favours use of glucose

glycogen, triglyceride and protein synthesis increase

Question 14

how does exercise affect insulin on the muscles

Answer 14

via adrenaline also induces GLLUT4 and synergises with insulin

Question 15

what are the effects of insulin on fat

Answer 15

GLUT 4 inserted and favours uptake of glucose
Triglyceride storage increased
export of FFA and glycerol is reduced
LPL exported to endothelium where is extracts FFA from VLDL

Question 16

what is glucagon release driven by inhibited by

Answer 16

amino acids and antagonised by glucose

Question 17

what are the effects of glucagon on the liver

Answer 17

glucagon is a GPCR receptor and linked to Gs
glycogen breakdown and gluconeogenesis increases
presence of G6Pase allows glucose export
fatty acids used as an energy source and for ketone body production

Question 18

what are the effects of glucagon on fat and muscle

Answer 18

high levels of glucagon causes lipolysis in adipocytes nd proteolysis releasing AA for gluconeogenesis in muscle

Question 19

when is it common to see high levels on glucagon in the blood

Answer 19

pathologically during ketoacidosis and sepsis and glucagon normally cleared by the liver

Question 20

what is the structure and function of somatostatin

Answer 20

peptide hormone - mostly 28aa in gut
released from D cells of stomach duodenum and pancreas
acts in paracrine - stimulated by lumen H+ and inhibited by ACh
acts on G cells to inhibit the release of gastrin
inhibits release of CCK and secretin as insulin and glucagon if it can get into the cells

Question 21

how does exercise affect blood glucose

Answer 21

adrenaline signals via cAMP to enhance glucose production in liver via cori cycle
glycogen breakdown in muscle and GLUT4 insertion via intrinsic AMPK
fatty acid release from adipocytes

Question 22

what is diabetes mellitus

Answer 22

failure of insulin action leads to high plasma glucose which is lost in urine taking water with it

Question 23

what are the symptoms of DM

Answer 23

polyuria
polydipsia
weight loss blurred vision
ketoacidosis in type 1

Question 24

what is DM type 1 causes and effects

Answer 24

primary defect in ability to produce enough insulin
autoimmune disease and B cells destroyed
excess glucagon leads to lipolysis and proteolysis and glluconeogenesis and ketogenesis in the liver

Question 25

what is DM type 2 cause and effect

Answer 25

primary defect is an impaired cellular response to insulin - receptor down regulation or reduced signalling
plasma insulin often high and strongly associated with obesity

Question 26

what are the characteristics between type 1 and type 2 DM

Answer 26

check photos

Question 27

what is the management of type 1 DM

Answer 27

always need insulin
balancing diet and insulin
risk of hypoglycaemia

Question 28

what is the management for type 2 DM

Answer 28

diet to reverse problem
drugs to enhance insulin secretion such as sulphonylureas/inretins
drugs to enhance insulin sensitivity - pioglitazone
drugs to inhibit gluconegenesis - metformin