Question

how are the alveoli desinged to maximise the exchange or gases ...
purple BTS !!​

Answer 1

Alveoli :

• These are balloon like structure located inside the lungs.

• A large number of alveoli increases the surface area for the exchange of gases.

• Human alveolar sir face when spread can cover area of 80 metre square.

Mechanism :

1. Air is taken in into the body through nostrils where it is filtered by hairs and mucus.
2. The air then passes down through trachea.
3. Chest cavity becomes larger due to flattened diaphragm and lifted ribs.
4. Air is sucked in into the lungs and fills the alveoli.
5. Oxygen is taken by blood from alveoli to blood vessels.
6. Blood releases carbon dioxide into alveoli that it brings from the whole body.
7. Haemoglobin in blood takes up oxygen and carries its to tissues which are deficient in oxygen.
8. Oxygen is then transported to all the cells in the body by respiratory pigment and due to diffusion pressure.
9. Carbon dioxide is transported in dissolved form in blood.
10. From blood, carbon dioxide passes to the alveoli.
11. Chest cavity is compressed due to relaxation of ribs and diaphragm.
12. Air is forced out of lungs to atmosphere.