1. While muscle cells respond in an all-or-none manner, the extent of force that they generate can be modified by a number of factors.

A. Describe the mechanisms whereby individual skeletal muscle cells can modify force development.

B. With these muscle cells working to generate force, a reliable energy source is necessary. Energy in the form of ATP is essential to the contractile process. Describe the cellular sources of energy for skeletal muscle fibers and how those energy sources play a role maintaining muscle activity at low- and high-intensities of activity.

C. With all of these different energy sources, are all muscle cells equal in how they utilize these resources? Describe any differences in anatomy/physiology that make these fibers unique.

D. Given the answers to the questions above, one major question still needs to be explored. If a muscle (like the bicep) is stimulated by the CNS to contract, and at best the fibers involved are showing unfused tetani, how do we have a smooth, muscle contraction? 

3. While sitting in class you realize that on some days your hand fatigues more quickly from taking notes in class, than on other days. Explain what (physiological) type of muscle(s) is active on these different occasions and why they would fatigue at different rates. Remember to cite your sources. 

4. All individuals, regardless of fitness level, require a resting cardiac output of approximately 5 L/min. Average Joe, a relatively inactive college student, has an average resting heart rate of 72 bpm, while super Simon, an elite marathon runner, has an average resting heart rate of 48 bpm. Calculate the stroke volume at rest for both Joe and Simon. 

5. Referring back to question 3, both Simon and Joe undergo an exercise stress test at their school's human performance lab. During the test, each individual's heart rate is monitored as they perform exercise to the point of exhaustion. At the peak power output before exhaustion, both Joe and Simon's maximum heart rate reaches 195 bpm. Calculate each individual's peak cardiac output, assuming that their stroke volumes are the same as at rest. What does this mean to the overall health of each individual? Remember to cite your sources. 

6. Ion channels within the conduction system of the heart determine the frequency of contractile cycles generated by the heart. Describe the autorhythmic properties of the heart, with particular emphasis on the ion channels involved in the pacemaker potentials. Remember to cite your sources. 

7. Cardiac output is in part determined by changes in stroke volume. Identify the 3 factors involved in the control of stroke volume. Remember to cite your sources.