Breathing Mechanics
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Respiratory
- Respiratory Overview
- Airway Anatomy
- Alveoli
- Breathing Mechanics
- Gas Exchange in Tissues
- Nervous Control of Breathing
- Respiratory Defense Systems
- Breathing/Respiration
- Governed by changing differential pressures in chest cavity and airway
- Inhalation
- 1. Diaphragm and intercostal muscles contract
- Diaphragm moves downward, rib cage elevates to expand thoracic cavity
- 2. Vacuum (negative pressure) in pleural cavity pulls lung
- Lungs are surrounded by thin, fluid-lined space called pleura, which contains the intrapleural space (pleural cavity)
- Negative pressure (vacuum) of intrapleural space pulls lung in contact with expanding thoracic wall
- 3. Lungs expand to fill space
- 4. Vacuum (negative pressure) pulls air into lungs
- Alveoli expand due to decrease in negative pressure and influx of air
- Gas exchange between capillaries and alveoli of lung
- 1. Diaphragm and intercostal muscles contract
- Exhalation
- This is a passive process, dictated by natural elasticity of tissue
- Forced expiration (ex: during exercise) involves abdominal muscles and distinct set of intercostal muscles to shrink chest cavity
- 1. Diaphragm relaxes and intercostal muscles relax
- Diaphragm moves up and rib cage moves down
- 2. Elastic recoil of alveoli pulls pleural cavity and thoracic cavity inwards
- 3. Lung volume shrinks
- 4. Increased pressure in lung pushes air out
- This is a passive process, dictated by natural elasticity of tissue
- Important Terms
- Tidal volume = volume of air that moves into lungs during each inspiration
- Some air doesn’t reach alveoli = stuck in respiratory dead space
- Respiratory rate = number of breaths per minute
- Tidal volume = volume of air that moves into lungs during each inspiration