How does transport of gases occur in the circulatory system?

Transport of gases in the circulatory system primarily occurs through the diffusion of oxygen (O2) from the alveoli in the lungs to the capillary blood. This process is driven by the concentration gradient; when air reaches the alveoli, the concentration of oxygen is higher in the alveoli than in the blood. As a result, oxygen diffuses across the alveolar membrane and into the bloodstream, where it can bind to hemoglobin in red blood cells for transport to various tissues and organs in the body.

This mechanism of gas exchange is fundamental to respiratory physiology and highlights the role of passive transport, where movement occurs naturally from areas of higher concentration to those of lower concentration without the need for energy. It is a critical step in the overall process of respiration and ensures that oxygen is readily available for cellular processes.