Endocrinology 5 - Insulin Action

Question 1

Which receptor does insulin incorporate into the muscle and adipose tissue?

Answer 1

The GLUT 4 receptor, which enhances glucose uptake

Question 2

Which amino acids are inhibited by insulin?

Answer 2

Gluconeogenic amino acids, including alanine, argenine, isoleucine, and leucine.

Question 3

Describe the process that gluconeogenic amino acids cause in the cell.

Answer 3

• Enter the cell via transporters
• Amino acids are converted to proteins
• Pyruvate and lactate are needed to make glucose.

Question 4

Describe what happens to triglycerides in the blood following insulin action.

Answer 4

• Insulin increases lipoprotein lipase receptors
• Triglycerides enter the cell and are broken down to non-esterified fatty acids.
• Non esterified fatty acids react with glycerol-3-phosphate to make triglceride.
• Release of triglyceride from the cell is inhibited

Question 5

What is splanchnic circulation?

Answer 5

Circulation via the gut and the liver, so nutrients are processed before the reach the tissues.

Question 6

Describe the process of ketone body production.

Answer 6

• Non-esterified fatty acids enter the cell
• Converted to fatty acyl coA
• Converted to acetyl co A, acetoacetate and eventually acetone.
• This is inibited by insulin

Question 7

Describe what happens in the fasting state.

Answer 7

• Low insulin to glucagon ratio
• Proteolysis occurs (breakdown of muscle)
• Lipolysis occurs
• Hepatic glucose output increases
• The muscle uses lipid
• Ketogenesis increases - brain can use ketone bodies

Question 8

Describe the presentation of type 1 diabetes and why.

Answer 8

• There is absolute insulin deficiency due to lack of insulin production
• Patients are usually thin - in a state of fasting as glucose uptake cant occur
• Both ketone bodies and glucose will be in the urine, as the renal threshold is overtaken
• Constantly drinking, weeing lots.

Question 9

Where does insulin resistance occur?

Answer 9

• The liver, muscle and adipose tissue

- There is enough insulin to supress ketogenesis and proteolysis

Question 10

What are the two pathways insulin binding to its receptor causes?

Answer 10

• MAP kinase pathway which encourages growth and proliferation
• P13 kinase pathway which induces metabolic actions

Question 11

What happens to growth in insulin resistance?

Answer 11

• There is a lack of glucose uptake so insulin production from the pancreas increases
• This causes hyperinsulinaemia
• This results in increased growth stimulation, which causes polycystic ovaries, clotting, high blood pressure and heart disease.

Question 12

What are the results of insulin resistance?

Answer 12

• High triglycerides, low HDL
• High glucose levels
• Waist circumference increases
• Hypertension

Question 13

Describe the presentation of type 2 diabetes.

Answer 13

• Insulin resistance
• 60-80% obese
• Dyslipidaemia (abnormal distribution of lipids in the blood)
• Later insulin deficiency

Question 14

What modifications need to be taken upon diagnosis with type 2 diabetes?

Answer 14

Smoking cessation, increased activity, calorie control, and a healthy diet. Fibre should increase and sodium levels should decrease.

Question 15

Why do many patients with type 2 diabetes have increased waist measurement?

Answer 15

The cells around your stomach area are more metabolically active. When the layer of fat becomes thick, insulin resistance at the adipocytes occurs.

Question 16

What is the response to hypoglycaemia?

Answer 16

• The patient will eventually secrete their own glucagon.

- A relative can give them an intramuscular injection