Heart rate is the number of beats per time. The difference between heart rate and pulse rate is the expansion of an artery caused by the ejection of blood from the left side of the heart. The doctors check the pulse to check the heart rate.

If the amount of carbon dioxide in your body increases and oxygen decreases, your body responses by breathing deeper and more frequent breathing out/exhaling carbon dioxide.

Oxygen debt is the additional oxygen that your body needs to take in after a harsh exercise to restore your body back to normal.

Both respiration and breathing means the same thing but there is one difference between the two words. Breathing is a process where you breathe in and out constantly. However, respiration is when the body breaks down the oxygen for the cells in the body. So in conclusion, breathing is a physical process and respiration is a chemical process.