Cardiovascular System: What activities change heart rate? 

Heart Rate in Humans and Dogs

Circulatory System is also known as the Cardiovascular System

Root Words:  Cardio - Heart.   and      Vascular - Blood Vessels

How to measure? Once you've found the pulse, use a timer and count the beats for 30 seconds. Multiply that number by 2.  The is the BPM or Beats Per Minute

https://kidshealth.org/en/parents/take-pulse.html

How quickly does heart muscle beat in our pets? https://www.cuteness.com/article/check-heart-rate 

How does Blood move through the heart? https://www.pbs.org/wgbh/nova/heart/heartmap.html 

My favorite heart diagram: https://www.texasheart.org/heart-health/heart-information-center/topics/heart-anatomy/ 

These are some Fun Facts: https://cvm.ncsu.edu/10-amazing-animal-heart-facts/