Question 21 – Communication and homeostasis - Questions

In a physiological study on a small mammal, researchers investigated the autonomic nervous regulation of heart rate. Under baseline (normal) conditions, the animal's resting heart rate was measured to be $bpm130\text{ bpm}$ . The following experimental observations were recorded:

When the parasympathetic cardiac (vagus) nerve was surgically severed, the resting heart rate increased to $bpm210\text{ bpm}$ .
When the sympathetic cardiac nerves were surgically severed, the resting heart rate decreased to $bpm110\text{ bpm}$ .

Suggest two conclusions about the nervous control of resting heart rate in this mammal that can be drawn from these observations. Use quantitative evidence from the data to support your conclusions.

Identify:

The specific structure in the heart wall (the pacemaker) where these autonomic nerves terminate to modulate heart rate.
The neurotransmitter released by the postganglionic parasympathetic nerve terminals at this site.

When the parasympathetic cardiac (vagus) nerve was surgically severed, the resting heart rate increased to $bpm210\text{ bpm}$ .
When the sympathetic cardiac nerves were surgically severed, the resting heart rate decreased to $bpm110\text{ bpm}$ .

Identify:

The specific structure in the heart wall (the pacemaker) where these autonomic nerves terminate to modulate heart rate.
The neurotransmitter released by the postganglionic parasympathetic nerve terminals at this site.

Communication and homeostasis

Question 11

Communication and homeostasis

Question 11

Communication and homeostasis

Question 11

Communication and homeostasis Questions

Communication and homeostasis

Question 11

Communication and homeostasis Questions