Human metabolism lecture 4

Question 1

Energy storage

Answer 1

• TAG = most efficient way but need mechanisms for transport
• Also glycogen, can make and degrade glycogen simultaneously

Question 2

Tissues w/o mitochondria

Answer 2

• Glycolysis = entirely cytoplasmic
• RBC entirely dependent on glucose as E source
• Cori cycle (liver converts lactic acid back to glucose)

Question 3

Starvation in tissue w/ mitochondria

Answer 3

• Range of fuels
• Limited availability of body carb (only small amount of glycogen)
• Best = fat

Question 4

Inhibition of glucose utilisation

Answer 4

• Body glycogen used 24-48hr of starvation
• FA replace glucose in muscle, ketone in brain
• Blood brain barrier = impermeable to FA

Question 5

PDH

Answer 5

• When active, pyruvate is committed to complete oxidation
• Needs to be inhibited
• PDH kinase phosph + inhibits PDH

Question 6

PFK

Answer 6

• FA/ketone body ox ↑ which ↑ [citrate], inhibits PFK

- GLUT4 inhibited

Question 7

Ketone bodies as signals

Answer 7

• Antilipolytic
• Ketone bodies limit own precursor
• Inhibit supply of glycerol

Question 8

Body protein in starvation

Answer 8

• Indication = N excretion
• As starvation proceeds, ↑ ammonia, ↓ urea excreted
• Alanine + glutamine = most important aa
• Sources of pyruvate for alanine (glucose, C skeletons, muscle glycogen)
• Sources of pyruvate for glutamate (C skeleton form other aa)