Glucose homeostasis

Question 1

Rate limiting step in B cells

Answer 1

Glucokinase (hexokinase 4) main glucose sensor.

Question 2

Insulin release mechanism

Answer 2

Glucose enters via GLUT 2, glucokinase metabolises into g6p converted into ATP, blocks channels at cell membrane, leads to release of K+, stimulates CA2+ gated receptors, CA2+ enters cell.
Release of stored insulin and synthesis of new insulin.

Question 3

Insulin storage

Answer 3

Stored as proinsulin, undergoes proteolytic cleavage, releases C Peptide. And leftover is insulin made of 2 chains connected by disulphide bonds.
C peptide acts as marker

Question 4

Incretin effect

Answer 4

Oral consumption leads to a greater increase in plasma insulin levels than IV since the gut stimulation leads to more insulin secretion.

Question 5

GLP1

Answer 5

Secreted in response to nutrients in gut.
Produced from L - cell
Stimulates insulin, suppresses glucagon.
Increases satiety

Question 6

First phase insulin release FPIR

Answer 6

Normal ppl have insulin stores released immediately after a large meal. Not present in T2DM

Question 7

Insulin binding to Insulin receptor

Answer 7

Binds to extracellular A sub-unit domain. Causes conformational change in tyrosine kinase domains of B sub-units

Question 8

Ketogenesis

Answer 8

low blood glucose prevents entry of acetylCoA into krebs cycle
two acetylCoA - acetoacetylCoA
+ another acetylCoA forms HMGCoA breaks down to acetoacetate

Question 9

3 major ketone bodies

Answer 9

acetoacetate
acetone
B - hydroxybutyrate

Question 10

symptoms of ketoacidosis

Answer 10

presence of ketones in urine
smell of acetone on breath
coma
excessive thirst
increased rate of breathing