Gluconeogenesis and Physiology

Question 1

Why does gluconeogenesis not occur in the fed state?

Answer 1

• High blood glucose causes insulin release and a drop in glucagon.
• Insulin increases fructose 2,6-bisphosphate and counteracts the effects of glucagon.

Question 2

What is the function of the Cori Cycle

Answer 2

Prevents lactic acidosis during exercise.

Question 3

Describe the Cori cycle

Answer 3

• Glycolysis in the muscle generates lactate (anaerobic).
• This travels via the blood to the liver.
• Gluconeogenesis in the liver is used to convert lactate into glucose.
• Glucose enters the blood and can be used by the muscles.

Question 4

Draw a diagram of the Glucose Alanine Cycle

Answer 4

Question 5

Describe the Glucose Alanine Cycle

Answer 5

• Important when muscles are broken down during fasting.
• Pyruvate is converted to alanine in the muscle and then back again in the liver.
• Pyruvate + glutamate<=> Alanine + 2-oxoglutarate
• Nitrogen from glutamate ends up in the excretory product urea.

Question 6

Describe the generation of Glucose from Glycerol

Answer 6

• Triglycerides are broken down the glycerol during lipolysis in adipose tissue.
• Occurs during fasting.
• Transported in the blood to the liver where it is converted to dihydroxy-acetone phosphate and eventually glucose.

Question 7

What Happens in a Sprint?

Answer 7

• Muscle cells produce lactate from glucose.
• Cardiac cells convert lactate to pyruvate.
• Gluconeogenesis in the liver keeps the muscle cells supplied with glucose.