Oxygen from the air enters the bloodstream at what location?*1 pointcardiac notchpulmonary veinparanasal sinusesalveoli

Oxygen from the air enters the bloodstream in the alveoli. Here's a step-by-step explanation:

1. When we breathe in, air enters our body through our nose or mouth.
2. This air then travels down the trachea (windpipe) and into the bronchi, which are the main passageways into the lungs.
3. The bronchi branch off into smaller tubes called bronchioles, which end in tiny air sacs known as alveoli.
4. It is in these alveoli that oxygen from the air is transferred into the bloodstream. The walls of the alveoli are extremely thin and surrounded by tiny blood vessels called capillaries.
5. Oxygen passes through the walls of the alveoli and into the blood in the capillaries. At the same time, carbon dioxide, a waste product, passes from the blood into the alveoli and is then exhaled out of the body.