How does the surrounding temperature affect the heart rate of a cold-blooded animal

I really have no idea, unless it causes the heart rate to increase as the temperature gets warmer?

Also, how does this impact the physiological activities of the animal?

Even a short answer is fine, I can probably figure it out from there

Thanks in advance.

Cold-blooded organisms don't necessarily have cold blood. They simply can't regulate their body temperature to maintain a constant internal temperature.

As the organism cools, their entire metabolism slows down. Lower metabolism means that they don't need a higher heart rate, so the heart rate slows down.

As the creature warms up in the sun, the metabolism increases, thus it needs greater circulation throughout its body, so the heart rate increases.

Hope this helps.