What is one change in the blood as it flows through respiratory system?

The main change in the blood as it flows through the respiratory system is the exchange of oxygen and carbon dioxide between the blood and the air in the lungs.

- In the lungs, the blood travels through tiny blood vessels called capillaries, which are located in the walls of the alveoli (air sacs). The walls of the alveoli are very thin, allowing for the exchange of gases.

- As the blood flows through the capillaries, oxygen from the air diffuses into the blood, while carbon dioxide diffuses out of the blood and into the air. This process is facilitated by the difference in partial pressure of gases between the alveoli and the blood.

- The oxygen-rich blood then leaves the lungs and is pumped by the heart to the rest of the body, providing the cells with the oxygen they need to function.