Chapter 4: Breathing

Question 1

Inhalation

Answer 1

1: Diaphragm contracts(moves downwards)
2: Intercostal muscles contract=ribcage lifts
3: Thoracic cavity volume - increase
•Thoracic cavity air pressure - decrease (air pressure is less than atmospheric pressure)
4: Air containing oxygen goes down air passages into lungs

Question 2

Exhalation

Answer 2

1: Diaphragm relaxes(moves up to normal position)
2: Intercostal muscles relax=ribcage moves down
3: Thoracic cavity volume - decreses
• Thoracic cavity air pressure - increases ( pressure becomes higher then atmospheric pressure.)
4: Air containing CO2 is forced out of the lungs