In animals, gaseous exchange takes place in the alveoli in the lungs. Generally, animals breath-out (exhale) carbon dioxide and breath-in (inhale) oxygen. Thus, carbon moves from the blood in the form of carbon dioxide into the alveoli in the lungs while the oxygen inhaled moves from the alveoli in the lungs to the blood where it is transported round the body as oxyhaemoglobin.
During respiration, humans take in air which contains oxygen and the oxygen gas then moves from the lungs into the blood . The blood helps to distribute the oxygen to other parts of the body for their proper functioning.
When we breathe out, we give out carbon dioxide as a result of the carbon which is taken up from the blood into the lungs and subsequently given out to be used by plants for their photosynthetic processes.
I think it’s because when you do it on purpose you don’t bit hard. Accentidal will hurt more cause you by into it hard. There’s certain parts that are more sensitive Hope that helped
