Diabetes Flashcards
How is diabetes defined?
A metabolic disorder where there is elevated blood glucose due to:
- resistance to action of insulin and/or
- insufficient insulin secretion
What is the main glucose transporter?
GLUT4 - dependent on insulin
What is gluconeogenesis?
Production of glucose
What is glycogenolysis?
Breakdown of glycogen
What is the key anabolic hormone to get glucose into cells?
Insulin
What are the minor catabolic hormones involved in glucose homeostasis?
Catecholamines (NA, AD) GH Cortisol Free fatty acids Incretins
What are the 3 major cell types in the pancreas?
Alpha-cells - produce glucagon
Beta-cells - produce insulin
Theta-cells - produce somatostatin
What does somatostatin inhibit?
Insulin & glucagon
How is insulin secreted?
- Extracellular glucose is transported into b-cells via GLUT2
- Glucose is metabolised which increases ATP:ADP ratio
- This causes closure of ATP-dependent K+ channels, causing depolarisation
- Ca2+ channels open
- Exocytosis of insulin-containing vesicles
What are the 2 phases of insulin secretion?
- Existing granules released - rapid onset, lasts 10mins
2. Stored granules mobilised to be released - prolonged plateau
What are the actions of insulin?
- Promotes glycogen synthesis
- Promotes fusion of vesicles & transporter insertion into cell walls to facilitate glucose uptake
- Promotes protein synthesis & inhibits protein breakdown
- Promotes lipogenesis & inhibits lipolysis
- Promotes mitogenesis
Is glucagon secretion increased by?
Low blood glucose levels
What is glucagon suppressed by?
Insulin
What is the function of glucagon?
- Stimulates gluconeogenesis & glycogenolysis
- Increases hepatic fatty acid oxidation & ketone formation
- Stimulates lipolysis in adipocytes
What is the cause of type 1 diabetes?
Autoimmune destruction of beta-cells causing insulin deficiency
