4.1.3

Explain how skeletal muscle contracts by the sliding filament theory.

An action potential causes the release of calcium ions form the sarcoplasmic reticulum. The calcium ions bind to troponin causing the troponin and tropomyosin to move and uncover binding sites on the actin for the myosin to attach to. The myosin head then attaches to the actin myofilament forming a cross bridge. With the release of a phosphate group, the power stroke takes place, sliding the actin towards the M line. The ADP molecule is then released. As a new ATP molecule attaches to the myosin head, the link between the actin and myosin weakens and the cross bridge detaches. As the ATP is split into ADP and a phosphate group, the myosin head is energized and again attaches to the actin, forming a cross bridge as the cycle repeats.

4.1.1

Label a diagram of a motor unit

3.3.11

Evaluate the relative contributions of the three energy systems during different types of exercise.

3.3.10

Discuss the characteristics of the three energy systems and their relative contributions during exercise.

Based on the information in the chart:

Evaluate each energy system and their roles during different types of exercise (endurance athlete, baseball player, sprinter), as well as the main nutrient(s) used and the byproducts produced

3.3.9

Describe the production of ATP from glucose and fatty acids by the aerobic system.

In the presence of oxygen, pyruvate is processed by the Krebs cycle, which liberates electrons that are passed through the electron transport chain producing energy (APT).

Fats are also broken down by beta-oxidation that liberates a greater number of electrons thus more ATP. In the presence of oxygen and in extreme cases protein is also utilized.

Acetyl-CoA

3.3.8

Explain the phenomena of oxygen deficit and oxygen debt.

Oxygen deficit – when oxygen need and oxygen supply do not match during the first moments of exercise.

Oxygen debt – (now better known as Excess Post-exercise Oxygen Consumption…. (EPOC)) – During recovery from exercise, oxygen consumption continues at a greater rate than needed at rest.

• O2 consumption remains elevated after exercise:

1. To rebuild ATP and Pcr stores in the cells
2. O₂ is “borrowed” from hemoglobin, especially myogloblin during initial stages of exercise and must be “repaid”

• Oxygen cost to help offset increase body temp following intense exercise