accelerator and vagus nerve

So my book describes that: when we excercise the CO2 concentration builds up and action potentials are sent down the accelerator nerve, and when we stop exercising the activity of the accelerator nerve decreased. But what I don't understand is: why aren't action potential also sent down the vagus nerve to help reduce the heart rate to normal?

Reply 1

tazmaniac97

OP

12

Is it because a decrease in the activity in the accelerator nerve is enough to bring the heart rate back down :dontknow:

or something

Reply 2

reneetaylor

11

The heart rate IS reduced back to normal due to action potentials. Stretch receptors in the walls of the cartoid arteries send signals (action potentials) to the cardiovascular centre during vigorous exercise ( as they tend to swell during exercise.) The response to this is a decrease in heart rate.

Reply 3

tazmaniac97

OP

12

Original post by reneetaylor

The heart rate IS reduced back to normal due to action potentials. Stretch receptors in the walls of the cartoid arteries send signals (action potentials) to the cardiovascular centre during vigorous exercise ( as they tend to swell during exercise.) The response to this is a decrease in heart rate.

No but I meant why aren't action potentials sent down the vagus nerve DUE to a decrease in carbonic acid concentration detected by chemoreceptors?

Reply 4

reneetaylor

11

Original post by tazmaniac97

No but I meant why aren't action potentials sent down the vagus nerve DUE to a decrease in carbonic acid concentration detected by chemoreceptors?

They are. Why wouldn't they be? I'm lost, does it say so in the book?

Reply 5

tazmaniac97

OP

12

Original post by reneetaylor

They are. Why wouldn't they be? I'm lost, does it say so in the book?

It doesn't mention that the chemoreceptors detect the pH returning back to normal and then sending action potentials down the vagus nerve. It just says that the chemoreceptors detect a low pH of blood and then send action potentials down the accelerator nerve.

Reply 6

reneetaylor

11

Original post by tazmaniac97

It doesn't mention that the chemoreceptors detect the pH returning back to normal and then sending action potentials down the vagus nerve. It just says that the chemoreceptors detect a low pH of blood and then send action potentials down the accelerator nerve.

Okay, I'm reading the bullet point just above the diagram.

-Blood pressure is monitored by stretch receptors in walls of the carotid sinus. This is a small swelling in the carotid artery. If blood pressure rises to high, perhaps during vigorous exercise, the stretch receptors send signals to the cardiovascular centre, which responds by reducing the heart rate.

The signals are sent from the cardiovascular centre, which needs to obviously send signals down the vagus nerve, which reduces the heart rate.

I'm not talking about when you start exercising, I'm talking about when you're exercising vigorously and your blood pressure rises too high. Which obviously leads to a decrease in heart rate due to the chemoreceptors detecting a change in ph -blah blah haha. :smile:

In short when we stop exercising action potentials from the cardiovascular centre in the medulla oblongata are sent toward the vagus nerve to decrease heart rate, due to a number of factors.

If you have the OCR book, all of the points should be above the diagram (page 29)

accelerator and vagus nerve

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