Glucose Homeostasis Flashcards
(33 cards)
What is the normal blood glucose concentration?
4-5mmol/L
At what blood glucose concentration does unconsciousness, coma or death can occur
When it falls below 2mmol/L
What does persistent hyperglycaemia lead to
Diabetes Mellitus
What are the hormones that act to increase glucose levels in plasma
- Glucagon
- Cortisol
- GH
- Catecholamines
What hormone(s) act to decrease blood glucose concentration?
Insulin

What type of diabetes is most prevalent? Describe the percentages
Type 2
What is the structure is the pancreas gland?
Retroperitoneal structure
Describe the micro anatomy of the pancreas exhaustively and outline functions
98% Excorine Acinar cells- secrete hormones into small intestine via duct
2% ;- islets of langerhans
What are the 3 type of cells in the Islets of Langerhans and what do they secrete?
Alpha- glucagon
Beta- insulin
delta- somatostatin
What are the type of junctions between islets of langerhan cells and what is their significance?
Gap junction - allow small molecules to pass between cells- paracrine communication
Tight junction- create small intercellular spaces.
What type of communication is between islets cells
Paracrine
What does insulin do?
Reduce blood glucose levels hence stimulate growth and development
What other hormones affect insulin secretion
Glucagon inhibit beta cells
Somatostatin inhibit beta cells

What is the effect of insulin?
Glycogenesis
Uptake of glucose via GLUT4
Glycolysis
Increase protein synthesis- amino acid transport increase
Lipolysis decreases
Lipogenesis increases
What’s the effect of glucagon in the body
Hepatic Glycogenolysis
Gluconeogenesis
Amino acid transfer into liver
Increased lipolysis
Hence glucose blood levels increase

Describe the intracellular process in beta cells which stimulates the release of insulin
Glucose enters beta cells via GLUT2
Glucose converted to G-6 phosophate via Glucokinase IV
ATP synthesised; inhibits k+ ion channels.
More K+ stay in beta cells.
K+ stimulates Ca2+ channels
Ca2+ influx and stimulates production and release of insulin from vesicles.
Describe the synthesis of insulin
Insulin is made from pro-insulin
C-peptide is cleaved off from pro-insulin
What key hormone is involved in the incretin effect?
Glucagon like peptide-1 (GLP)
Describe where and how GLP-1 is made
Gut hormone
Secreted in response to nutrients in gut
Made from L-cell; a transcription product of pro-glucagon gene.
What is the function of GLP-1?
STIMULATES INSULIN
Suppresses glucagon
Increases satiety
What causes the short half life of GLP-1 and what treatment can GLP-1 can be used for.?
Short half life- due to rapid degradation from the enzyme dipeptidyl peptidase- 4
(DPPG-4 inhibitor) is treatment used to increase GLP-1
Used in treatment of diabetes mellitus
Describe the insulin receptor and how it responds when insulin binds to it?
Insulin bind to EXTRACELLULAR DOMAIN of insulin receptor. I.e. binds to alpha subunit
This causes conformational change in Tyrosine kinase domains of beta subunits?
Describe incretin effect
In normal, When you eat plasma insulin goes up significantly and peaks 1hr after eating and decreases to reach normal levels.
when there’s a significant increase in insulin levels when given oral glucose as opposed to given IV glucose (this is due to GLP1 and GIP) .
people with type 2 diabetes don’t show this

Describe the first phase insulin release graph for type 2 diabetes and normal people
For type 2: after glucoses given; insulin increases but not very much an decrease gradually but not to the level of normal glucose tolerance





