Mammalian fuel metabolism & integration and regulation

Question 1

Ketone body formation occurs in ______. Ketone body breakdown occurs in _____.

Answer 1

Ketone body formation occurs in the LIVER. Ketone body breakdown occurs in NON-LIVER structures.

Question 2

T/F

The liver is not metabolically flexible

Answer 2

False. The live is METABOLICALLY FLEXIBLE

Question 3

5 major fates of glucose-6-phosphate

Answer 3

1. Can be converted into glc in the liver and dumped into the blood when [blood glc] drops
2. Glc-6-P not immediately needed in the blood is stored as glycogen
3. May be burned for energy
4. Excess glc-6-p not required in blood is converted into acetyl-CoA and used to make fat
5. Can be oxidized in PPP to make NADPH to be used for reductive biosynthesis

Question 4

Which requires less [glucose] to reach a high Vo/Vmax?

Answer 4

Hexokinase (in the muscle)

Question 5

What happens to amino acids not required for synthesis of proteins or other compounds?

Answer 5

They are deaminated and degrated into Acetyl-CoA and Kreb’s intermediates. N goes into urea cycle.
Glucogenic amino acids can be used to make glucose

Question 6

Where does fat synthesis occur in humans?

Answer 6

in the liver

Question 7

What do adipocytes do when fuel is required in the body?

Answer 7

adipocytes hydrolyze fats with lipases into free fatty acids which are then transported via the blood to the heart and skeletal muscles

Question 8

epinephrine

Answer 8

• stimulates the activation of tryacylglycerol lipase

- results in an increased rate in glycogen breakdown in muscle

Question 9

Insulin

Answer 9

Counters the effect of epinephrine

Question 10

What tissue accounts for over 50% of O2 consumption in a resting human and over 90% during active exercise?

Answer 10

Skeletal muscle, ya nub

Question 11

What can skeletal muscle burn?

Answer 11

fatty acids, ketone bodies or glc

Question 12

Resting muscle

Answer 12

converts mostly fatty acids or ketone bodies into acetyl-CoA which goes into Kreb’s, then to oxidative phosphorylation to make ATP
-enough O2 to run aerobically

Question 13

Moderately active muscle

Answer 13

uses blood glucose as well as fatty acids or ketone bodies and runs aerobically

Question 14

Maximally active muscle

Answer 14

ATP demand is so great that blood cannot supply enough O2 for fully aerobic catabolism

• glycogen is broken down anaerobically to lactate
• glc formed from breakdown of glycogen is used to supply energy for contraction
• epinephrine will result in an increased rate in glycogen breakdown in muscle

Question 15

Accumulation of lactate will ________ the pH and ______ muscle efficiency

Answer 15

Accumulation of lactate will DECREASE the pH and REDUCE muscle efficiency