Term
| What role does oxygen play in the process of aerobic metabolism? |
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Definition
| Since oxygen is required in aerobic metabolism, cellular respiration considerably increases demand on the respiratory system to deliver enough oxygen to generate enough ATP for sustained endurance activity. |
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Term
| Describe the by-products of energy production from ATP PCr, glycolysis and oxidation. |
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Definition
| ATP PCr's byprodut is a phosphate molecule (P), that is broken away from creatine and is added to ADP, forming ATP. Glycolysis' by-product is pyruvic acid, which gets converted to lactic acid. Oxidation's byproduct is water, which prevents acidification of the cell at the end of oxidative phosphorylation by combining hydrogen atoms with oxygen. |
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Term
| What is lactic acid and why is it important? |
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Definition
| Lactic acid is a substance produced by glycolysis that is removed from the cell through oxidation. It's important because it serves as a fuel source during exercise by being oxidized in type I muscle fibers with a high density of mitochondria, it can be transported from the muscle fiber it was produced in and sent elsewhere via the lactate shuttle, and can be sent to the liver to be converted back to pyruvic acid, and eventually back to glucose during the Cori cycle. That way, it can be reused in working muscles. |
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Term
| Discuss the interaction between the three energy systems with respect to the rate at which energy can be produced and the sustained capacity to produce that energy. |
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Definition
| The three energy systems always interact with each other during energy production, but the degree at which they work varies depending on the type of exercise that's being performed. For example, in a short sprint or a brief period of increased activity, the ATP-PCr system will be producing the most energy. If it's a long, endurance based activity however, oxydative system will be the primary system. The only time two systems are close to equal are when they're transitioning from one dominant system to another. |
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Term
| How do type I muscle fibers differ from type II fibers in their respective oxidative capacities? What accounts for those differences? |
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Definition
| Muscle Fiber I fibers have more mitochondria and a higher concentration of oxidative enzymes compared to type II fibers. Known as the fast-twitch fibers, fiber II fibers are better suited for glycolytic energy production since they need it faster. This results in type I muscles having a higher oxidative capacity, allowing them to access more energy over a prolonged period of time. Even then, endurance training can improve type II fibers as well by producing more mitochondria and developing muscles throughout the body. |
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