Metabolism 2

Question 1

What is lipolysis

where does glycerol go
where goes triglyceride go

how long is the carbone chain

Answer 1

release of the attached FFA from glycerol

glycerol goes straight into glycolysis

FFA, albumin takes into beta oxidation

then into Krebs cycle, and finally ETC

18 carbon chain, 16 cycles

glycerol = 16

beta oxidation=360

total of 376 ATP

Question 2

ATP/O2 ratios for glucose and fats

what needs more oxygen

Answer 2

32ATP / 12 O2 = 2.67 for glucose

120 ATP / 52 O2 = 2.31 P/O ratio for fat

More oxygen is needed to get the same amount of ATP
from lipids compared to carbohydrates!

Question 3

RER ratios

kcal/O2 glucose and fats

Answer 3

RER = VJCO2 / VJO2
* If RER = 1.0, carbohydrate is the fuel
* If RER = 0.71, lipid is the fuel
* If 1.0 > RER > 0.71, the fuel is a mix of carbohydrate and lipid

5.05 kcal / L O2 glucose

4.69 kcal / L O2

Question 4

Keenan’s VO2 is 4.0 L O2/min and assume he is burning
100% carbohydrates.
What would his VO 2 be if his body switched to burning
100% lipid?

Answer 4

4 x 5.05 kcal

20.2 kcal

20.2/4.69

4.3 L / min

Question 5

what influences fuel selection

when are proteins used

Answer 5

• Exercise intensity
• Exercise duration
• Substrate availability
• Diet
• Sex
• Training status

Amino acids provide relacvely lidle ATP in well- nourished individuals
* Total body RER is a reasonable escmate of nonprotein
RER during exercise
* Correccon for amino acid oxidacon is typically not used even when available

Question 6

Fuel used during high INTENSITY

fuel used during low INTENSITY

results of the test

Answer 6

More fat burned at lower intensities

more glucose burned at higher intensities

• Lipolysis was maximal at the lowest exercise intensity
• FFA mobilization decreased as exercise intensity
  increased
• During 2 hr of exercise at 65% VO2max, plasma FFA
  oxidation progressively increased over time
• In recovery from high-intensity exercise, plasma [FFA]
  increased, indicating FFA mobilization from adipose
  tissue to replenish muscle-stored triglycerides

Question 7

Pros and cons of carbs at fats

Answer 7

LIPIDS
Pros:
* Greater energy yield/unit weight (9.1 kcal/g vs. 4.2 kcal/g)
* Greater amount stored in body
Cons:
* Takes more time
* Unsustainable at higher intensities

CARBS
Pros:
* Greater energy yield/O2 (~7.7% more)
* Can be used anaerobically
Cons:
*Use up quicker and less readily available – need to replete

Question 8

what do cells rely on

what happens even if you have a lot of fat at high intensities

Answer 8

more on the available structure
carb loading increases carb oxidation

at high intensities, fat burning is low, no matter what