One scientist established a technique that could map the pathways of oxygen movement in human body. When he traced the movement of oxygen molecules, he found two facts in normal healthy people: (1). Some oxygen molecule (O2 ) was inhaled into the lung, but never make up its way to reach the heart; (2). Some oxygen molecules (O2) could pass through the heart more than ten times after entering the blood.
a. Explain how and why (1) happened
b. Explain why and how (2) happened