Respiratory System Crossword

What is an extensive system of branching internal tubes with the respiratory surface found at their tips?
What are internal sacs lined with moist epithelium and found in most terrestrial vertebrates?
What are extensions, or outfoldings, of the body surface specialized for gas exchange?
What is the transfer of a substance from a fluid moving in one direction to another fluid moving in the opposite direction?
What sheet of muscle separates the thoracic cavity from the abdominal cavity?
Where are the paths for food and air found?
Where is air inhaled through? (voice box)
What are grapelike clusters of air sacs called?
What is the alternate inhalation and exhalation of air?
What is the maximum volume of air that we can inhale and exhale during forced breathing called?
What is an iron-containing pigment that turns red when bound with oxygen?
What are the places that control our breathing automatically?
What are the secretions that are required to keep the alveoli from sticking shut due to the surface tension of their moist surface called?
What is the windpipe called?
In the lung, the bronchus branches repeatedly into finer and finer tubes called?