13.1 : 呼吸

Respiration is a sequence of events that allows the exchange of gases between the atmosphere and the body.

During respiration, the body releases chemical energy from food molecules through oxidation.

During oxidation, carbon and hydrogen combine with oxygen, releasing energy, carbon dioxide, and water.

Oxygen is essential for metabolism on a cellular level, while carbon dioxide helps achieve appropriate pH levels.

The respiratory system eliminates carbon dioxide from the circulating blood and rapidly absorbs oxygen from the atmosphere per the body's needs, even during an extreme workout. 

This system begins when air enters the nose and mouth and continues via the respiratory airways and the lungs.

The process of respiration involves pulmonary ventilation, diffusion, and perfusion.

Pulmonary ventilation, commonly called breathing, is an air exchange into and out of the lungs.

Diffusion refers to the natural process of gases moving spontaneously between the alveoli in the lungs and the red blood cells.

Finally, perfusion refers to the red blood cells flow to and from the alveolar capillaries.