21.4 Chapter Human Structure and Function

Two phases of pulmonary ventilation

Inspiration, expiration

Inspiration

Period when air flows into lungs

Expiration

Period where gases exit the lungs

Boyle’s law

When constant temperature pressure of a gas varies inversely with its volume

Inspiration in Boyle’s law

Air rushes in and Volume is increased by enlarging dimensions, Means pressure decreases

Expiration in Boyle’s law

Air leaves, less space volume decreases, pressure increases

Mucles in resting inspiration

Diaphragm

Muscles in active inspiration

Diaphragm, external intercostals

Muscles in resting expiration

None, elastic recoil

Mucles in active expiration

Abdominals, internal intercostals

Atmospheric pressure

Pressure of air outside the body

Intrapulmonary pressure

Pressure of air in lungs, causes lungs to stick to the side of thoracic cavity