Diabetes mellitus Flashcards
Which cells are GLUT-4 glucose co-transporter proteins present in?
Muscle cells
Adipocytes
Cardiomyocytes
How is GLUT-4 translocated?
Insulin regulated, binding onto the insulin binding domains associated with the beta chains, inducing conformation change of tyrosine kinase. Intracellular phosphorylation stimulates pathway for GLUT-4 synthesis and integration.
What stimulatory effect does insulin have on mycoytes?
Protein synthesis: Hyperglycaemic conditions, there is a sufficient availability of glucose to satisfy the ATP demand through glycolysis, and subsequent oxidative phosphorylation = requirement for AAs is reduced
Glucose uptake: GLUT-4 glucose transporters whiten vesicles are released integrating with the cell surface membrane, to facilitate the diffusion of glucose intracellular
Glycogenesis: Insulin activates hexokinase-4, involved in initial phosphorylation into glucose-6-phosphate. Also upiregulates glycogen synthase
What are the inhibitory effects of insulin in muscle cells?
Proteolysis is inhibited: Reduces activity of proteases and proteasomes
Indirectly inhibits gluconeogenesis
Inhibits activity of glucose-6-phosphate.
What effect does cortisol have on glucose during hypoglycaemia?
Stimulates proteolysis and gluconeogenesis
What effect does IGF-1 and growth hormones have on protein synthesis?
Enhances protein synthesis
Overview: What 4 pathways are unregulated by insulin in carbohydrate metabolism?
Glucose uptake via GLUT4
Glycogen synthesis
Glycolysis
Conversion of pyruvate into acetyl CoA
Overview: What two pathways are down regulated by insulin in carbohydrate metabolism?
Glycogenolysis
Gluconeogenesis
Overview: What 3 pathways are up regulated by insulin regarding lipid metabolism?
Lipogenesis
Triglyceride synthesis
Cholesterol synthesis
What 2 pathways are inhibited by insulin regarding lipid metabolism?
lipids oxidation
Triglyceride breakdown
How is alanine essential in gluconeogenesis?
Alanine is converted into pyruvate –> osaloacyyte –> phosphoenolpyruvate
What effect does glucagon have on gluconeogenesis?
Stimulates pryruvate and lactate uptake into hepatocytes, in addition to AAs.
What effect does insulin have on lipoprotein lipase?
Potentiates lipoprotein lipase activity
What is the structure of triglycerides?
Triglycerides consist of a glycerol backbone associated with three esterified fatty acid molecules.
Which particles are triglycerides packaged in?
Chylomicrons and VLDLs
What is the function of lipoprotein lipase?
Circulating triglycerides associated with chylomicrons are hydrolysed by the action lipoprotein lipase, presented on adipocyte cell surface membrane receptors into glycerol and NEFA
Where are lipoprotein lipase located?
On the cell surface membrane of adipocytes
What is the fate of glycerol and NEFA, released by the lipoprotein lipase?
Enter within the adipocytes cites, to undergo series of condensation and esterification reactions to form triglycerides which are stored in adipose tissue
What effect does insulin exert on intracellular lipase?
Inhibits the intracellular lipase (hydrolyses triglycerides to release fatty acid)