How does oxygen travel from person lungs to tissues and organ?

Oxygen travels from the lungs into the bloodstream and subsequently to tissues and organs through the process of gas exchange and systemic circulation. The steps can be summarized as follows:

1. Breathing (Inhalation):

- When you inhale, air is taken into the lungs through your nose or mouth.

- Inside the lungs, oxygen from inhaled air diffuses across the thin walls of alveoli (tiny air sacs in the lungs) into the surrounding capillaries.

2. Pulmonary Circulation:

- The oxygen-carrying capillaries collect into pulmonary veins.

- Pulmonary veins carry oxygenated blood back to the heart (specifically, the left atrium).

- From the left atrium, oxygenated blood then moves to the left ventricle.

3. Cardiac Output:

- During systole (when the heart contracts), the left ventricle pumps the oxygenated blood into the aorta, the main artery of the body.

4. Systemic Circulation:

- The oxygenated blood exits the heart through the aorta and travels through arteries, which branch into smaller arterioles.

- The oxygen-carrying blood vessels branch further, becoming even smaller vessels known as capillaries that permeate tissues and organs throughout the body.

5. Capillary Exchange:

- In capillaries, oxygen diffuses out of the blood and into the surrounding body tissues, where it is used for cellular respiration by cells.

- At the same time, carbon dioxide (a waste product of cellular respiration) diffuses from the tissues into the capillaries.

6. Return of Deoxygenated Blood:

- Deoxygenated blood (carrying carbon dioxide) is collected in capillaries and then in venules, forming veins.

- The deoxygenated blood flows through larger veins, eventually returning to the heart (right atrium).

- From the right atrium, the deoxygenated blood passes into the right ventricle, setting in motion the pulmonary circulation cycle again.

This cycle of gas exchange in the lungs, circulation through the heart and blood vessels, and diffusion at the capillary level ensures a continuous supply of oxygen to tissues and organs, while simultaneously removing carbon dioxide for exhalation.