The process of taking in oxygen and expelling carbon dioxide is called ____.
Answer: respiration

The main organs of the respiratory system include the __, __, and _____.
Answer: lungs, diaphragm, trachea

The purpose of the respiratory system is to ____.
Answer: supply the body with oxygen and remove carbon dioxide

The exchange of gases in the lungs occurs in tiny air sacs called __.
Answer: alveoli

How does oxygen from the air we breathe get into our bloodstream?
Answer: Oxygen diffuses across the walls of the alveoli and into tiny blood vessels called capillaries.