Neuronal communication

Question 12

A physiological study investigated the nervous regulation of heart rate in a mammal. Under normal conditions, the resting heart rate is $bpm75\text{ bpm}$ . The following experimental observations were recorded:

When the parasympathetic cardiac (vagus) nerve is severed, the resting heart rate increases to $bpm115\text{ bpm}$ .
When the sympathetic cardiac nerves are severed, the resting heart rate decreases to $bpm65\text{ bpm}$ .

a.

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.

[4]

b.

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.

[2]

Neuronal communication

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Question 12

A physiological study investigated the nervous regulation of heart rate in a mammal. Under normal conditions, the resting heart rate is $bpm75\text{ bpm}$ . The following experimental observations were recorded:

When the parasympathetic cardiac (vagus) nerve is severed, the resting heart rate increases to $bpm115\text{ bpm}$ .
When the sympathetic cardiac nerves are severed, the resting heart rate decreases to $bpm65\text{ bpm}$ .

a.

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.

[4]

b.

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.

[2]

Neuronal communication

Question 12

Neuronal communication Questions

Neuronal communication

Question 12

Neuronal communication Questions