Physioex 8.0 Exercise 6

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Electrical Stimulation
Activity 1: Direct Heart Stimulation

1. Did you see any change in the trace? No change in the trace 2. Why or why not? This is because it needs more simulation 3. Did you see any change in the trace? I did see a change in the trace 4. Why or why not? There is double stimulation

5. Describe the change you see in the trace. How does it differ from the baseline trace? The trace increased from the baseline trace 6. What effect do the repeated stimuli have on the heartbeat trace? Describe the trace. The heartbeat trace showed a flat line then jumped back to normal and then flat lined again it continue to follow this trace continuously. 7. What part of the trace shows the refractory period? The atrial contraction is the part of the trace that shows the refractory period 8. Does summation occur? No summation

9. Why is it important that summation not occur in heart muscle? Summation would increase the Heart muscle contractions which would lead to heart attack.

Activity 2: Vagus Nerve Stimulation

1. Describe the effect of the vagus nerve stimulation on the heartbeat. The vagus nerve stimulation caused the heartbeat to flatline and then restart and react normally 2. Soon after you applied the stimuli, did the heart rate increase or decrease? Soon after the stimulation is applied the heart rate decreased 3. Why? This is because the cardiac muscle cells depolarize 4. How do the sympathetic and parasympathetic nervous systems work together to regulate heart rate? Sympathetic neurons increase the heart rate while the parasympathetic neurons decrease the heart rate and the heart stimultaneously receives both neurons signals 5. Complete the following: As heart rate decreases, cardiac output _______ (assuming stroke volume remains the same). As heart rate increases, cardiac output ________ (assuming stroke volume remains the same). 6. What does this tell you about the parasympathetic...
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