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willow25 willow25
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11 years ago
Hi,
I am doing a post lab on frog physiology of the heart.

I need help with this question:

Do the rate and amplitude always change together? Why or why not?

I know generally speaking, they change together. However, I don't think this is always the case. I just don't understand why/how

any help would be appreciated!
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#1
Staff Member
Educator
11 years ago
No, during exercise induced tachycardia the amplitude (volume) and rate both go up because you need to rapidly move the blood throughout your body. However, when a trained person is at rest his heart rate is much slower BECAUSE his heart is stronger and can pump a greater volume with each beat. Also, if you're dehydrated, your blood volume will decrease and your heart will have to speed up to compensate. It's a very carefully balanced system.

Hope this helps.
Mastering in Nutritional Biology
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willow25 Author
wrote...
#2
11 years ago
Thank you for the information. I guess I should have explained that this is for a frog heart physiology lab. We had to put the frog heart through different tests; increasing temperature, adding ca2, k+, atropine, ach


Do any of these effect the rate and amplitude so that they do not increase or decrease together?
wrote...
#3
Staff Member
Educator
11 years ago
Atropine will increase heart rate.

The initial effect of potassium should be to decrease the heart rate.

Calcium should be positive inotropic (increasing the force of contraction) and positive chronotropic (increasing the heart rate).
Mastering in Nutritional Biology
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