What happens when blood enters the lungs?

When blood enters the lungs, a crucial process called gas exchange takes place within the tiny air sacs known as alveoli. Here's what happens during this process:

1. Deoxygenated Blood Arrival: Blood containing low levels of oxygen (deoxygenated blood) is pumped from the heart into the lungs through the pulmonary arteries.

2. Oxygen Uptake: Inside the alveoli, the capillaries (tiny blood vessels) surrounding the alveoli have very thin walls, allowing for efficient diffusion of gases. Oxygen from the inhaled air in the alveoli moves across these capillary walls and enters the bloodstream.

3. Carbon Dioxide Release: Simultaneously, carbon dioxide (a waste product of cellular respiration) moves out of the capillaries and into the alveoli. During this process, the deoxygenated blood becomes oxygenated and releases carbon dioxide.

4. Oxygenated Blood Return: The now oxygenated blood leaves the lungs through the pulmonary veins and returns to the heart. The heart then pumps this oxygen-rich blood to various tissues and organs in the body, providing them with the necessary oxygen for cellular metabolism.

The exchange of oxygen and carbon dioxide between the alveoli and the capillaries in the lungs ensures that the body gets a fresh supply of oxygen and releases waste carbon dioxide during each breath. This vital process maintains the proper balance of gases in the bloodstream and is essential for sustaining life.