1) __ is the force that moves air into the lungs.
2) When pressure on the inside of the lungs decreases, what happens?
3) How is air pressure inside the lungs decreased? Due to __ between the two layers of the __, the lungs follow with the __ and __.
4) Muscles involved in expanding the thoracic cavity include the __ and __.
5) As the lungs expand in size, __ keeps the __ from sticking to each other so they do not collapse when internal air pressure is low.
1) atmospheric pressure
2) higher pressure air flows in from the outside
3) by increasing the size of the thoracic cavity; surface tension/ pleura/ chest wall/ expand
4) diaphragm (contracts and lowered)/ external intercostal muscles (pull ribs up and out= increasing volume which decreases pressure)
5) surfactant/ alveoli