PhysioEx 6 Activity 2

Describe how the sympathetic and parasympathetic nervous systems work together to regulate heart rate.

Parasympathetic helps decrease the heart rate by the vagus nerve. Even though this can decrease the heart rate the sympathetic division also has a neuron that attaches to the heart where it can be able to increase the heart rate. So in intense situations, the sympathetic system works to increase the heart rate but in relaxing times our heart stays normal or decreases from the parasympathetic division.

The usual pacemaker of the heart is..

is the sinoatrial node

Extreme vagus nerve stimulation affects the heart by...

stopping the heart completely.

Vagal escape probably involves...

sympathetic reflexes

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...

the parasympathetic nervous system has more control over heart rate.

he branch of the autonomic nervous system that dominates during exercise is...

the sympathetic branch.

The response that resumed the heartbeat after the vagus nerve stimulation is called...

vagal escape.

Parasympathetic stimulation reaches the heart through...

vagus nerves, which are cranial nerves

What do you think would happen to the heart rate if the vagus nerve was cut?

If the vagus nerve was cut then the sympathetic division will take over and will increase the heart rate.

Explain the effect that extreme vagus nerve stimulation had on the heart. How well did the results compare with your prediction?

The extreme vagus nerve caused the heart to decrease its rate and eventually caused it to stop as the vagus nerve kept stimulating signals to it. This is due to the vagus nerve being a part of the parasympathetic division. My prediction was correct.

Explain two ways that the heart can overcome excessive vagal stimulation.

The heart can overcome excessive vagal stimulation by vagal escape and sympathetic reflexes.

What do you think will happen if you apply multiple stimuli to the heart by indirectly stimulating the vagus nerve?

The heart rate will decrease and the heart will stop.

The effect of the parasympathetic nervous system on the heart is to..

decrease the heart rate.

The SA (sinoatrial) node in the human heart is located...

in the right atrium.

The vagus nerve carries...

signals that decrease the heart rate