Introduction to Diabetes Mellitus: Insulin Action Flashcards
How does insulin affect Glucose, protein and lipid?
- Glucose: decrease hepatic glucose output
- Protein: decreased proteolysis
- Lipid: decrease lipolysis, and decrease ketogenesis
In which tissues is Glut-4 usually found?
Most glucose uptake is via Glut-4
It is particularly abundant in MUSCLE and ADIPOSE tissue
How is Glut-4 different to Glut-2?
Glut-4 is insulin responsive whereas Glut-2 isn’t
how does GLUT-4 work
Insulin stimulates Glucose transporter 4.
It has hydrophobic elements on the outside embedded in the membrane and a hydrophilic core which allows glucose into the cell.
It sits in vesicles within the cytoplasm. Insulin recruits them to the membrane causing glucose uptake.
How does insulin affect proteolysis?
Inhibits proteolysis
- amino acids can be oxidised in the muscle cell and insulin prevents this oxidation.
- insulin increases the re-synthesis of proteins from amino acids.
How does cortisol affect proteolysis?
Promotes proteolysis (cortisol is a stress hormone that is concerned about increasing blood glucose)
What effect does glucagon have on uptake of amino acids by the liver?
Increases uptake of amino acids by the liver and protein synthesis is stimulated by insulin.
What do gluconeogenesis and glycogenolysis in the liver contribute towards?
What increases gluconeogenesis?
What inhibits gluconeogenesis?
Glucose produced enters circulation as Hepatic Glucose Output
Insulin inhibits gluconeogenesis.
Somatotrophin, cortisol, catecholamines and glucagon increase gluconeogenesis.
How do triglycerides enter adipocytes?
Triglycerides must be broken down by LIPOPROTEIN LIPASE before they can enter the adipocyte.Insulin stimulates Lipoprotein Lipase.
TAGs are broken down by lipoprotein lipase to:
Glycerol and
Non-Esterified Fatty Acids (NEFA) which are absorbed by the adipocyte
How is glucose converted to triglycerides?
Glucose can be converted to NEFA
Glucose can also be chopped in half to produce glycerol
They can then be stuck together to a fatty acid to make triglycerides
How are the effects of insulin in the blood different to insulin in adipocytes?
Blood - insulin promotes the breakdown of triglycerides (so that they can enter the adipocytes)
Adipocytes - insulin promotes the formation of triglycerides so that they can be stored
what does the adipocyte in the gut show.
What is an indicator for ischaemic heart disease
- the adipocyte is different in activity and endocrine regulation.
- the omental fat/waist circumference is a simple indicator of someones risk of ischaemic heart disease.
What are the two ways in which glycerol can be used by the liver?
Glycerol can be used to make TRIGLYCERIDES for storage
Glycerol can be used to make GLUCOSE by adding 2 glycerols, that supports hepatic glucose output
What are the three main ketone bodies?
- Acetone
- Acetoacetate
- 3-hydroxybutyrate
What are the effects of insulin and glucagon on fatty acid metabolism?
Insulin inhibits the conversion of fatty acyl coA to ketone bodies
Glucagon promotes the conversion of fatty acyl coA to ketone bodies