Story of Insulin Flashcards
What happens to insulin level during fed and fasting states?
It increases during fed state and decreases during fasting state
glucagon increase during fasting state
Both insulin and glucagon levels decrease with time
What are the insulin counter-regulatory hormones?
Cortisol, epinephrine, norepinephrine, glucagon when glucose levels are low
Glucagon is not the only insulin counter-regulatory hormone
Which two tissues don’t need insulin to absorb glucose and will absorb available glucose at all times?
Brain and RBCs
What is the fate of fuels in the brain?
In the fed state, the brain uses glucose almost exclusively and burns most of it all the way to CO2 and water. Amino acids are taken up for protein synthesis and neurotransmitter synthesis. Fats can’t cross the blood brain barrier.
What is the fate of fuels in the RBCs?
At al times, the RBCs use glucose almost exclusively but since they don’t have mitochondria burn it only as far as pyruvate, then convert it to lactate (Cori cycle). There is no amino acid or fatty acid uptake in the RBCs. They can’t use either
What are the glucose transporters and which one is insulin-sensitive?
GLUT1,2,3,4
GLUT 4 is the transporter that is insulin-sensitive
Which glucose transporter has low affinity?
GLUT 2 - varies with concentration
Where is insulin produced?
pancreas beta cells in the islets of langerhans
Beta cells release insulin in repines to high glucose
Blood glucose is low in response to insulin release (glucose removed from the blood)
What occurs at adipose tissue when insulin is released in the blood?
It promotes the synthesis in the liver and VLDL formation
What does insulin promote in the muscle?
Promotes synthesis of proteins
What does insulin promote in the liver?
It promotes glycolysis (for conversion to fat)
What is second messenger system is used by insulin?
Trimeric G protein (Tyrosine Kinase Receptor) -> PIP3 -> PKB (Ser/Thr Kinase)
