Exercise 6: Cardiovascular Physiology: Activity 2: Examining the Effect of Vagus Nerve Stimulation Lab Report
Pre-lab Quiz Results
You scored 100% by answering 4 out of 4 questions correctly.
1. The effect of the parasympathetic nervous system on the heart is to
You correctly answered: a. decrease the heart rate.
2. The branch of the autonomic nervous system that dominates during exercise is
You correctly answered: b. the sympathetic branch.
3. Parasympathetic stimulation reaches the heart through
You correctly answered: d. vagus nerves, which are cranial nerves.
4. The usual pacemaker of the heart
You correctly answered: c. is the sinoatrial node.
Post-lab Quiz Results
You scored 100% by answering 4 out of 4 questions correctly.
1. Extreme vagus nerve stimulation affects the heart by
You correctly answered: a. stopping the heart completely.
2. Vagal escape probably involves
You correctly answered: c. sympathetic reflexes.
3. Research shows that, in the absence of neural and hormonal influences, the SA node generates action potentials at a
frequency of approximately 100 times per minute. However, the resting heart rate is approximately 70 beats per minute,
which suggests that
You correctly answered: b. the parasympathetic nervous system has more control over heart rate.
4. The SA (sinoatrial) node in the human heart is located
You correctly answered: c. in the right atrium
Review Sheet Results
1. Explain the effect that extreme vagus nerve stimulation had on the heart. How well did the results compare with your
prediction?
Your answer:
The heart rate decreases and stopped the heart temporarily. My prediction was on par.
2. Explain two ways that the heart can overcome excessive vagal stimulation.
Your answer:
The heart can overcome excessive vagal stimulation by using the sympathetic reflexes and the initiation of a rhythm by the
Purkinje Fibers.
3. Describe how the sympathetic and parasympathetic nervous systems work together to regulate heart rate.
Your answer:
Sympathetic increases heart rate. Parasympathetic decreases heart rate.
4. What do you think would happen to the heart rate if the vagus nerve was cut?
Your answer:
It would continually increase and never regulate.
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