What is the respiratory (or breathing) system?

The respiratory system includes the upper and lower respiratory tract. The upper respiratory tract consists of:

  • The nose and nasal cavity.
  • The throat (pharynx).
  • The voice box (larynx).

The lower respiratory tract consists of:

  • The windpipe (trachea).
  • Breathing tubes (bronchiand bronchioles).
  • Air sacs (alveoli).