Glucose homeostasis Flashcards
Why is glucose importnat
Energy substrate
Important in CNS
Can lead to unconsciousness, coma and death
What are the normal levels of glucose concentration
4-5 mmol/L
What hormones help to increase blood glucose
Glucagon
Cortisol
GH
Catecholamines
Why is it a challenge for people living with diabetes in terms of hormones
Only insulin which can lead to hypoglycaemia
Which diabetes type is the most prevalent
Type 2
Type 1
Last maturity onset diabetes of the young
Anatomy of the pancreas
It is a retroperitonael structure
How much is the pacrease is made out of exocrine secretions
98%
What are the different type of islet of langerhans
What are pancreatic polypeptide producing cells
Communicate between gap junctions and tight junctions
Paracrine communications between islet cells
What does somatostatin do in terms of pancreatic hormones
Keep both of the hormones in balance
Negative feedback hormone
What other function does insulin have apart from lowering blood glucose
imporatn in fetal growth and development
Reactions to an increase in blood glucose
How does insulin regulate glucose
Build up of glycogen stores - glycognesis
Breakdown of glucose - glycolysis
Increase uptake of glucose to cell - mediated by GLUT4 (predominantely in skeletal muscles and adipocytes)
Amino acids transport increases - increase in protein synthesis
Increase in lipogenesi s- decrease in lipolysis
Reaction to reduction in blood glucose
Reaction to reduction in blood glucose
Increase lipolysis
Increase gluconeogenesis
Increase hepatic glycogenolysis
Increase amino acid transport into liver
Glucokinase
GLUT-2 is not insulin sensitive
High affinity for glucose, whenver glucose in bloodstream reflected in B cell
Glucose is converted by glucokinase (hexokinase IV), not subject to negative feedback
Glucose - 6 - phosphate gives a good idea of how much glucose
High ATP produced which closes K+ channels
Membrane depolarisation which opens calcium channel gates
Calcium influx promotes insulin release
How are insulin and C-peptide related
Insulin is stored in proinsulin
Undergoes proteolytic cleavage
Breakdown protein C peptide gives better indication of how much insulin someone is producing as insulin is relatively unstable
What is the incretin effect
Gut hormones inhance insulin secretion and reduction in glucagon
GLP - 1 (glucagon like peptide)
Rpaidly degraded
Secreted in response to nutrients in the gut
Increasing levels of satiety
Treatment for diabetes
First phase Insulin Reponse
Respones gets blunted
Beta cells work too much and cannot produce load
Picture of insulin receptor
Insulin binds to extracellular part
Induces a conformational change in the tyrosine kinase domain of B subunit
