Energy Production II

Protein CHO Fat PyruvateAmino Acids Fatty Acids Acetyl-CoA TCA Cycle and Electron TS ATP produced

Carbohydrate Muscle glycogen ( g). 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 lactate + 2ATP glucose carbon dioxide + water ATP blood glucose glucose glycogen MUSCLE LIVER

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 O 2 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 PyruvateAmino Acids 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)=