During expiration, ________ pressure in the thoracic cavity causes air to leave the lungs.

Air passing along the respiratory tract is ________.

In the nose, the cilia beat upward carrying mucus and dust.

As air moves out during expiration, it cools and loses its moisture.

The human nose contains _____ nasal cavities.

The nasal cavities empty into the _________.

The moist membranes of the respiratory tract are protected by ________.

The ________ lead(s) from the nasopharynx to the middle ears.

The trachea lies behind or dorsal to the esophagus.

The esophagus opens only during ________.

The ________ is the voice box.

The ________ is held open by cartilaginous rings.

The bronchi lead into the right and left ________.

The bronchi branch into smaller passages called ________.