Question

1. when air enters the alveolar sac, what exchange occurs? gas carbon dioxide protein 13. when you breathe in, the diaphragm does what? contracts relaxes spasm

Explanation:

In the alveolar sacs, oxygen from the air diffuses into the blood and carbon - dioxide diffuses out of the blood into the air, which is a gas exchange process. When breathing in (inhalation), the diaphragm contracts to increase the volume of the thoracic cavity, allowing air to enter the lungs.

Answer:

1. Gas
2. Contracts