When you breathe, your lungs take in ___ and remove ___.

Identify this system.

_______ is/are made mostly of water and makes up about 55% of the blood

The part of the respiratory system that humans use for talking is the...

The small blood vessels where exchange of O₂ and CO₂ occurs are called...

The part of the lungs where gas exchange occurs is/are called.

When you breathe in, the lungs _________ in order to _________ air pressure, so that air will flow in.

The flap of tissue that covers the larynx so that food goes down the esophagus to the stomach and not down to the lungs is called the...