You can monitor your heart rate during exercise by buying a heart rate monitor that you wear on your wrist or on your arm which can easily display your real time heart rate.
Chemoreceptors identify a rise in carbon dioxide so heart rate and breathing rate is increased to increase oxygen around the body to the working muscles and to remove waste and decrease carbon...
Exertion on the body causes the need for blood to be circulated at a faster rate - thus the heart rate increases to make this happen. This can be a good thing.