Starvation

Question 1

What happens to glucose during a food deficit?

Answer 1

Glucose decreases

Question 2

What effects does low glucose have?

Answer 2

Decreased insulin production
Increased glucagon and noradrenaline production
Increased cortisol production (during early starvation)

Question 3

What affect does increased glucagon have on glycogenesis and glycogenolysis?

Answer 3

Activates glycogen phosphorylase - activates glycogenolysis

Inhibits glycogen synthase - inhibits glycogenesis

Question 4

How long do liver glycogen stores last?

Answer 4

12 hours

Question 5

How is blood glucose maintained after 12 hours?

Answer 5

Gluconeogenesis
AA in the muscle are transaminate to alanine.
Alanine is transported to the liver
Transaminated back to pyruvate using alpha-keto-glutarate.
Pyruvate froms glucose in gluconeogenesis

Question 6

What is the effect of glucagon on glycolysis?

Answer 6

Inhibits pyruvate kinase so inhibits

Question 7

What is the effect of glucagon on gluconeogensis?

Answer 7

Stimulate fructose-1,6bisphosphatase which is key enzyme in gluconeogenesis

Question 8

What is the effect of high acetyl CoA due to fatty acid breakdown?

Answer 8

It inhibits pyruvate carboxylase so stops pyruvate -> acetyl CoA
Activates pyruvate carboxylase which directs pyruvate to gluconeogenesis

Question 9

Why are there protein losses associated with fasting?

Answer 9

Proteins converted to alanine to fuel gluconeogenesis which decreases protein synthesis.
Increased production of urea - loss of nitrogen

Question 10

Why is lipogenesis increased?

Answer 10

Decreased insulin activates hormone sensitive lipase

Question 11

What is the fate of glycerol from lipolysis?

Answer 11

Enters gluconeogenesis to from glucose

Question 12

What is the fate of fatty acids from lipolysis?

Answer 12

Oxidised in beta oxidation to form acetyl CoA

Question 13

What is the fate of acetyl CoA?

Answer 13

TCA cycle.

Excess is used in ketogenesis

Question 14

What are ketone bodies used for?

Answer 14

Energy for the brain

Question 15

After 16 days of fasting what occurs in the brain for the use of ketone bodies?

Answer 15

Enzyme induction occurs to produce the enzymes needed to utilise ketone bodies for energy

Question 16

What are the effects of adaption?

Answer 16

Brain utilises ketone bodies for energy. Requirement for glucose decreases, rate of gluconeogenesis decreases. Less protein loss and nitrogen loss in the urine

Question 17

What happens to hormone levels during trauma?

Answer 17

Increased glucagon and adrenaline causing hyperglycaemia

Question 18

How does hyperglycaemia occur during trauma?

Answer 18

Insulin resistance - so glucose cannot re-enter cells
Increased gluconeogenesis due to increased glucagon.
Demand for glucose does not increase so it is not used up

Question 19

What happens in relation to the cori cycle during trauma?

Answer 19

Increased activity
Pyruvate converted to lactate
Transported to the liver
Lactate to pyruvate which is used in gluconeogenesis.
Glucose can not enter cells because of insulin resistance

Question 20

Why is there a marked protein loss during trauma?

Answer 20

Increased amount of glutamine used as fuel fro the immune system. Less available for protein synthesis