The hollow space inside of the digestive tract is the ________.

Much of the mucus in the mouth comes from the _____________ salivary gland under the tongue.

The __________ serves as a center for receiving and integrating sensory input and sending nerve impulses to another respiratory center to make necessary changes in the breathing pattern.

Platelets are produced from cells called ______.

The exchange of oxygen and carbon dioxide between air in pulmonary alveoli and blood in capillaries occurs by ______.

Quiet expiration requires the ______.

The inhaled air enters each lung lobe through a ______.

The respiratory centers are located in the ______.

___________ play an important role in regulating the airflow through the air passageways.

When _____________, blood pressure within the ventricles increases, which causes the AV valves to close and the semilunar valves to open.