functions during inspiration/respiration

Question 1

diaphragm

Answer 1

in: diaphragm contacts, creates larger thoracic cavity and more space for lungs to expand.
out: no energy required, diaphragm relaxes= exhale

Question 2

external intercostals

Answer 2

in: causes rib cage to expand; increasing volume of thoracic cavity (decreasing pressure, lower pressure than atmospheric pressure= pressure gradient that drives air in)
out: relax

Question 3

internal intercostals

Answer 3

in: can assist in drawing ribs down during forced breathing
out: assist in forced exhalation: depressed volume in thoracic volume