An example of an energy substrate?
Palmitic acid
Which of these substrate stores in the body can provide the most overall kilocalories?
Triglycerides
Protein can serve as an energy substrate if…
It is first converted to glucose
Which of the following is responsible for lowering the activation energy of a chemical reaction?
Enzyme activity
An anaerobic glycoltyic system would be the primary source of ATP for which running event?
800 m (1/2 miles)
In the absence of oxygen, the final product of glycolysis is?
Lactic acid
For aerobic metabolism, free fatty acids must be converted to acetyl-CoA via…
B-oxidation
Taking into account both oxygen requirements and ATP yield, which substrate is more efficient? Fat or glucose?
Glucose
In which part of the cell does oxidative phosphorylation occur?
Mitochondria
An athlete with a high percentage of type II fibers would exhibit which characteristics?
Few mitochondria, lower oxidative enzymes
Men and individuals with a higher BMI have _____ brown adipose tissue than women and individuals with a lower BMI
Less
What are the 2 key forms of carbohydrate?
Glucose & glycogen
Key forms of fat?
FFA’s and triglycerides
Building blocks of protein?
Amino acid
What is the source of energy for almost all metabolic processes?
ATP
ATP-PCr System
- Anaerobic
- Transfers energy from PCr to ATP via ADP
- catalyzed by creatine kinase
- provides energy for explosive, short duration movements
Glycolytic System
- breakdown (oxidation) of glycose
- anaerobic
- produces lactic acid
- produces 2-3 ATP molecules
- provides energy for high-intensity events (20s - 2min)
Glycolysis
Aerobic oxidation of glucose/glycogen through glycolysis –> feeds the Krebs cycle
Krebs Cycle
- uses end products of glycolysis, fatty-acid oxidation
- produces ATP
- feeds electron transport chain
Electron Transport Chain
Transports hydrogen ions from glycolysis and the Krebs cycle to produce ATP in mitochondria
What is the energy yield from oxidation of carbohydrate?
32 ATP from glucose, 33 ATP from glycogen
B-oxidation produces…?
acetyl coenzyme-A from fatty acids
Lactate acid as a source of energy during exercise:
- used as fuel for the fiber in which it is produced
- transported MCT transporters and used elsewhere
- can be reconverted to pyruvate, then glucose through gluconeogenesis in the liver
Summary of Substrate Metabolism
- Carbohydrate stores (glycogen) are limited compared to fat stores
- Carb is the preferred fuel source during exercise because it can be metabolized anaerobically
- complete oxidation of carb requires less oxygen than complete oxidation of fat
- carb stores are more accessible than lipid stores
