How does Earth and people breath?

Answer 1

Earth is a planet and has no respiratory system. It does not breathe.

Between 15 and 25 times per minute, humans breathe by contracting and expanding the diaphragm and intercostal muscles in their chests. This pulls the lungs into likewise expansion and contraction, which pulls in air (called inhaling). The air passes through the bronchial tubes and into the alveoli (little pockets that make up lungs).

Here, oxygen is heavily concentrated and is diffused (passed) into the pulmonary capillary. This is where oxygen enters the bloodstream and is transported to the rest of the body.

Exhaling, or breathing air out, entails the spent oxygen (now carbon dioxide) being diffused into the alveoli from the pulmonary capillary as the blood passes through to pick up oxygen. The process is an exchange of sorts and happens millions of times per second.

Now repeat. This is the breathing cycle.