Insulin Action

Question 1

Give 3 effects of insulin.

Answer 1

It promotes glycogen synthesis in the liver and muscle. It inhibits glycogenolysis in the liver and muscles. It stimulates glucose uptake in the muscle and liver. It promotes fatty acid synthesis.

Question 2

When insulin binds to the receptor, the receptor becomes what?

Answer 2

Autophosphorylated.

Question 3

Insulin receptor catalyzes what?

Answer 3

Tyrosine phosphorylation of Insulin Receptor substrates (IRS).

Question 4

Give 2 effects of insulin resistance.

Answer 4

In muscle cells - reduces glucose uptake, reduces glycogen synthesis. In liver cells - it reduces storage of glycogen. In fat cells - reduces effects of insulin, results in lipolysis and increases fatty acid conc. in blood.

Question 5

What does Insulin Receptor Substrates (IRS) do?

Answer 5

Activate several signalling pathways.

Question 6

Insulin receptor is a tetramer, what does that mean?

Answer 6

Contains two extracellular ɑ subunits connected by disulfide bonds, two intracellular β subunits connected to each ɑ subunits.

Question 7

Give 3 ways of how obesity contribute to insulin resistance.

Answer 7

Chronic inflammation. Oxidative stress. Hyperinsulinaemia. Lipotoxicity.

Question 8

Name an anti-diabetic drug used to treat insulin resistance.

Answer 8

Thiazolidinediones, also known as glitazones, are a group of oral anti-diabetic drugs designed to treat patients with type 2 diabetes.

Question 9

Name 2 hormones affecting insulin resistance in obesity.

Answer 9

Leptin. Adiponectin.

Question 10

Name the changes in leptin for obese patients who become insulin resistant.

Answer 10

Leptin increases insulin sensitivity normally, but in obesity they become resistant.

Question 11

Name the changes in adiponectin for obese patients who become insulin resistant.

Answer 11

Adiponectin increases insulin sensitivity, but decreases in obesity.