It is the functional unit of lungs:
Correct answer: A. Air sacs
- A. Air sacs
- B. Bronchioles
- C. Alveoli
- D. Bronchi
Explanation
The functional unit of the lungs is called the "alveolus" (plural: alveoli). Alveoli are tiny, air-filled sacs located at the ends of the respiratory bronchioles in the lungs. These sacs are where the exchange of oxygen and carbon dioxide takes place between the air in the lungs and the blood in the surrounding capillaries. This exchange of gases is essential for respiration, where oxygen is taken up by the bloodstream and carbon dioxide, a waste product, is released from the bloodstream into the lungs to be exhaled. The large surface area and thin walls of the alveoli facilitate efficient gas exchange.
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About Respiration
The human respiratory system includes the air passages, lungs, alveoli and breathing muscles, while gaseous exchange explains how oxygen enters blood and carbon dioxide leaves it by diffusion. The effects of smoking include damage to cilia and alveoli, reduced gas exchange, chronic bronchitis, emphysema and increased risk of lung cancer.
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