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Mechanics of Breathing
May 27, 2024
Lecture on Breathing Mechanics
Introduction
Discussed breathing processes: Inhalation and exhalation
Importance of volume changes in breathing
Focus on the mechanics behind these changes
The Sternum and Rib Connection
Sternum (Breastbone):
Located in the center of the chest
Technical name: Sternum
Ribs attach to the sternum
Ribs:
Total: 24 ribs (12 pairs)
7 pairs directly attached to the sternum
Intercostal Muscles
Location:
Between the ribs
Function:
Enable expansion and contraction of the chest
Control:
Controlled by nerves
Contract when instructed by the brain
Importance:
Facilitate outward movement of the ribs during inhalation
The Diaphragm
Shape and Location:
Dome-shaped muscle
Forms the floor of the chest cavity
Function During Inhalation:
Contracts and moves downward, flattening
Leads to expansion of the lungs and chest cavity
Lung Expansion
Ribs move out
Diaphragm moves down
Alveoli (air sacs):
Expansion corresponds to increased lung volume
Approximately 500 million alveoli in the lungs
Alveoli surrounded by an elastic protein called elastin
Elastic Properties of Alveoli
Elastin:
Acts like a rubber band
Stretches during inhalation
Facilitates alveolar expansion
Inhalation versus Exhalation
Inhalation:
Muscles (Intercostal and Diaphragm) contract
Volume increases
Requires chemical energy (ATP)
Exhalation:
Muscles relax
Elastin helps alveoli return to original size
Volume decreases
Driven by elastic potential energy
Summary
Breathing involves intricate coordination of muscles and elasticity
Inhalation requires energy; exhalation relies on stored elastic energy
Ensures efficient air exchange and lung function
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