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Mechanics of
Breathing
April 18, 2023
Mechanics of Breathing
April 18, 2023
Mechanics of Breathing
April 18, 2023
human rib cage human rib cage (breathing)
Mechanics of Breathingthoracic cavity: formed by: a) rib cage & intercostal musclesb) diaphragm• lined by pleural membranes
April 18, 2023
diaphragm
intercostal muscles bands of muscles
between ribs
thoracic cavity
trachea
Inhalationinhalation- involves:1. intercostal muscles contract• pull rib cage up & out2.diaphragm contracts (pulls down)• causing it to flatten out
April 18, 2023
diaphragm pulls down
intercostals pull up & out
InhalationCauses:• volume of chest cavity to ___________• therefore air pressure in chest __________ making
it __________ than atmospheric pressure• therefore air _____________ to equalize air
pressure
April 18, 2023
lowerrushes in
decreases
increase
April 18, 2023 7
Inhalation
Exhalation
April 18, 2023
exhalation- involves:1. intercostal muscles relax• rib cage returns to normal2.diaphragm relaxes• returns to normal
intercostals go back down& in
diaphragm goes back
up
ExhalationCauses:• volume of chest cavity to ___________• therefore air pressure in chest __________ making
it __________ than atmospheric pressure• therefore air _____________ to equalize air
pressure
April 18, 2023
higherrushes out
increases
decrease
April 18, 2023 10
Exhalation
Breathing Rate LabDo Breathing Rate Lab and hand in by the end of
class.
Mechanics of Breathing
April 18, 2023
External intercostal
musclesinvolved in normal
breathing
Internal intercostal
musclesinvolved when
forcefully exhalingex. blowing out a
candle
