SS1. Energy metabolism & liver

Question 1

Explain how glucose is taken up by liver.

Answer 1

1) high blood glucose stimulates secretion of insulin from pancreas
2) pancreas promotes uptake glucose by liver & muscle to store it as glycogen.

Question 2

How is glucagon transformed back to glucose when its needed?

Answer 2

Insulin levels decline, triggers secretion of glucagon.
1) pyruvate converted to glucose using lactate, glycerol and AA as precursor.
2 AA are deaminated first, results in production af ammonia (metabolised to urea). deaminated AA can be used as C skeletons for gluconeogenesis.
3) Mitochondria, formation of oxaloacetate through carboxylation of pyruvate
4) oxaloacetate is decarboxylated & phosphorylated by phophoenolpyruvate carboxykinase. Produces phosphoenolpyruvate (start of formation of glucose 6P)
5) Final step: hydrolysis of Glucose-6P to glucose in lumen of ER.

Question 3

What are examples of plasma proteins? (2)

Answer 3

Albumin and globulins.

Question 4

What is and the function of albumin?

Answer 4

Plasma protein, transports lipids and steroid hormones.

Provides most of colloid osmotic pressure that determines the flow of H2O and solutes across walls of capillaries.

Question 5

What is and the function of globulins?

Answer 5

alpha and beta globulins.
Made in liver, transports lipids & fat-soluble vitamins in blood,
y-globilins are ABs produced by WBCs.
Clotting factors (fibrinogen, prothromin) synthesised in liver.