glucose regulation

Question 1

what is the optimal range of which blood glucose must be kept at?

Answer 1

• between meals –> 4/6 mol/L

- post meals –> 10mmol/L

Question 2

what are the roles of the 3 major cell types found in the islets of langerhans?

Answer 2

• alpha cells–> glucagon
• beta cell–> insulin
• delta cells -> SST

centred are beta cells surrounded by alpha cells (richly vascularised) –> regulation of glucagon secretion via Insulin

Question 3

explain the processing of insulin

Answer 3

• preproinsulin–> proinsulin–> insulin + C-peptide + Zn atom + proinsulin
  contained within secretory granules awaiting stimulation via high glucose levels
• endopeptidases cleave cleave signal peptide (pre)
• endopeptidases remove C chain

Question 4

explain the process of insulin secretion

Answer 4

• vesicles released in response to high BG
• glucose sensors of B cells–> GLUT2 FD of glucose
• glucose–> g6p via glucokinase
• increased levels of ATP
• K channels opened when bound to ADP (K efflux)–> hyperpol
• ATP displaces ADP–> channel closure
• cell depolarised
• -50mV opening of VGCA
• ca influx causes secretion of vesicles via exocytosis

Question 5

summarise some facts about glucagon

Answer 5

• antagonistic Action to insulin
• alpha cells
• response to low BGL
• cleaved from pro-glucagon
• binds to GPCR
• elevates cAMP
• stimulates gluconeogenesis

Question 6

actions of glucagon include?

Answer 6

• promotion of gluconeogenesis
• promotion of glycogenolysis
• increased ketogenesis and lipolysis
• inhibits lipogenesis
• formation. of ketone bodies from FA oxidation (ketogenesis and lipolysis)

from substrates –> Long chain FA and AA (leu, lys)

Question 7

SST inhibits what?

Answer 7

• peptide hormone secretion
• glucagon
• insulin

Question 8

what is glucagon like peptide 1?

Answer 8

• synthesised from glucagon gene
• different processing than glucagon
• member of incretins
• promotes insulin-like action
• prepares to start releasing insulin
• role in reducing bolus motility and tells us were full

Question 9

what does DPP4 do?

Answer 9

• is an enzyme
• degrades GLP via disrupting processing
• reduces levels

Question 10

why is liraglutide beneficial?

Answer 10

• synthetic drug
• GLP like actions
• resistant to breakdown via DPP4
• anti-obesity therapy
• promotes insulin release and production

Question 11

why use SGLT2 inhibitors ?

Answer 11

• inhibition of co-transporters (anti porters) found in PCT of kidneys
• utilises NA gradient generated via BLM Na/K atpases
• allows XS glucose to be trapped within PCT–> urine
• osmotically active–> polyuria
• reduced glucose absorption

Question 12

define insulin resistance

Answer 12

An impaired biological response to insulin
– Resistance to insulin-stimulated glucose uptake – Increased lipolysis/FFAs
An impairment of normal glucose uptake by muscle and/or restraint in glucose production in the liver

• precedes type 2 D