The endocrine pancreas

Question 1

what is the difference between anabolic and catabolic pathways?

Answer 1

anabolic pathways build up and store energy for when required
catabolic pathways breakdown and release energy required for work

Question 2

what is the name of the process by which glucose is synthesised from glycogen?

Answer 2

glycogenolysis

Question 3

what is the name of the process by which glucose is synthesised from amino acids?

Answer 3

gluconeogenesis

Question 4

what is the normal range of blood glucose?

Answer 4

4.2 - 6.3mM

Question 5

what is the blood glucose level of someone hypoglycaemic?

Answer 5

< 3mM

Question 6

what hormones does each f the 4 pancreatic cells produce?

Answer 6

A cells = glucagon
B cells = insulin
delta cells = somatostatin
F cells = pancreatic polypeptide

Question 7

when proinsulin is cleaved it gives insulin and what other molecule?

Answer 7

C-peptide

Question 8

what is the main stimulus of insulin secretion?

Answer 8

glucose

AA’s also stimulate insulin release but glucose is the main one

Question 9

how does an increase in glucose cause insulin secretion?

Answer 9

when glucose levels rise, it enters the cell via GLUT transporters
this increases ATP within the cell which causes the Katp channel to close
closing the K channel = rise in K in the cell causing depolarisation
depolarisation triggers opening of voltage gated Ca channels
influx of Ca triggers insulin vesicles exocytosis into the circulation

Question 10

what type of glucose transporter is insulin dependant and where is this found?

Answer 10

GLUT 4 in muscle and fat tissue

Question 11

where is GLUT 1, GLUT 2 and GLUT 3 transporters found?

Answer 11

GLUT 1 & 3 = many tissues i.e. brain, kidney, RBC’s

GLUT 2 = B cells of pancreas and liver

Question 12

via what transporter does glucose enter the liver and why is this significant?

Answer 12

GLUT 2
glucose enters the liver independent of insulin status
glucose moves down a concentration gradient into the liver
(however insulin is required for transport into hepatocytes)

Question 13

what enzyme does insulin trigger which lowers blood glucose concentration?

Answer 13

hexokinase

Question 14

what hormone inhibits insulin release and how?

Answer 14

somatostatin (GHIH)
somatostatin decreases GI motility therefore release of glucose into blood stream and so glucose levels aren’t detected as quick

Question 15

why is the release of insulin in response to glucose via oral administration greater the that of IV administration?

Answer 15

with oral administration, vagal activity also stimulates the release of other GI hormones which stimulate insulin secretion

Question 16

what hormones form the glucose counter-regulatory control system?

Answer 16

glucagon
epinephrine
cortisol
growth hormone

Question 17

what type of receptors are glucagon receptors?

Answer 17

G-rpotein coupled receptors

Question 18

what is the actions of glucagon?

Answer 18

glucagon phosphorylates;
increase glyconeolysis
increase gluconeogenesis
formation of ketones from free fatty acids

Question 19

after a high protein meal with little carbohydrate, how does our blood glucose maintain within normal range?

Answer 19

amino acids trigger the release of both insulin and glucagon

because since amino acids trigger the release of insulin, since the meal has little sugar this would result in hypoglycaemia. but since it also stimulates glucagon, it can trigger gluconeogenesis

Question 20

does somatostatin inhibit or promote glucagon release?

Answer 20

inhibit

Question 21

does vagal activity increase or decrease insulin release?

Answer 21

increase

Question 22

during exercise, how does glucose entry into skeletal muscle increase?

Answer 22

entry into the skeletal muscle during exercise is insulin independent
GLUT 4 transporters migrate (even though in non exercising tissue they are insulin dependant)

Question 23

what is used as an energy source in order to spare the breakdown of protein?

Answer 23

conversion of free fatty acids to ketones

Question 24

how does type 1 diabetes result in ketoacidosis?

Answer 24

they are unable to produce insulin
the uptake of glucose is insulin dependant, therefore glucagon causes gluconeogenesis converting FFA’s into ketones
this is because there is low glucose concentration within the cell
(the body thinks it has low glucose, but it is actually really high in the plasma)
ketone absorption is also insulin dependant therefore there is a build up of ketones within the plasma resulting in acidosis