Transcript Energy Production II - University of Massachusetts Amherst

Energy Production II
Protein
CHO
Fat
ATP
produced
Amino
Acids
Pyruvate
Fatty Acids
Acetyl-CoA
TCA Cycle and
Electron TS
ATP
produced
Carbohydrate
Muscle glycogen (250-300g).
Stored in muscle
and used
there, it is not
transported
in the blood.
2. Blood glucose (90 mg/100ml blood) =
5g = 1 tsp.
Not used much by most tissues except after
a meal, reserved for the brain and "special"
situations
At rest: 250 mg glucose/min = 20 min of
glucose in blood at any one time.
.
During long, hard exercise can use 2g blood
glucose/min = 2.5 min unless replaced
3. Liver glycogen (60-100g).
Breakdown of
glycogen plus gluconeogenesis
(new glucose formation from amino acids,
lactate), replaces blood glucose being used
to maintain normal blood glucose levels.
glycogen
pyruvate
glucose
MUSCLE
lactate + 2ATP
carbon dioxide +
water + 30-36 ATP
blood glucose
glucose
LIVER
glycogen
FAT
Most fatty acids used for exercise are
transported from adipose tissue to muscle.
Some fat stored is stored in muscle
(intramyocellular lipid or IMCL) and can be
mobilized for use.
1. Requires a lot of oxygen
A 16 carbon fatty acid requires 23 oxygen
molecules vs. 6 O2 for glucose
2. Need to transport from adipose tissue
makes fat use minimal early in exercise.
3. Cannot sustain high-intensity exercise.
4. Slow – fat must undergo beta oxidation in
order to generate acetyl CoA for TCA cycle.
Protein
Only 5-10% of energy derived from oxidation
of protein. Use of protein depends heavily on:
1. Energy balance (deficit = more PRO used)
2. CHO available (low = more PRO used)
Amino acids derived from body protein can be
used to produce:
a. energy, via entry into TCA cycle
b. glucose, via gluconeogenesis
No true storage of protein. Protein used in
excess of dietary intake causes loss of lean
body mass.
Consequences of extended reliance on a lot
of protein for energy (e.g. for weeks,
months)?
Protein
CHO
Fat
ATP
produced
Amino
Acids
Pyruvate
Fatty Acids
Acetyl-CoA
TCA Cycle and
Electron TS
ATP
produced
Summary
Goal of CHO, fat and protein breakdown is
to generate ATP, the body’s energy currency.
Non-oxidative metabolism occurs in the
cytosol of the cell, oxidative metabolism
occurs in the mitochondria.
Acetyl CoA is the common entry point of all 3
energy sources into the TCA cycle (oxidative
metabolism)=