Ventilation and work of breathing Flashcards
Which pleura covers the thoracic wall, which covers the lung?
Parietal pleura covers the thoracic wall
Visceral pleura covers the lungs
What is the function of the 2 pleura?
Allows the membranes to slide past each other but not pull apart as the pleural cleft is filled with pleural fluid.
Allows movement of the lungs to be independent of other organs
In which direction do the lung pull?
Inwards as a result of the elastic recoil
The ribcage springing open pulls the thoracic cage inward/outward?
Outwards
The lung and the ribcage pull in opposite directions so how do they stay together?
Pleural fluid in the pleural cavity keeps them from pulling apart
Why is pressure at the apex more negative then the base?
Gravity makes the apex more open
What muscles are involved in inhalation?
Diaphragm moves down
External intercostal muscle contract and move up
Ribcage moves up and out
Uses scalene muscles, pectoralis minor muscle, serratus anterior muscle.
Is quite breathing passive?
Yes
What muscles are active during forced breathing?
Internal intercostal muscles
rectus abdominus
What factors affect the work of breathing?
Airway resistance
Lung compliance
Surface tension
What is airway resistance dependent on?
The diameter of the airways. Smaller diameter = higher resistance
What is lung compliance?
How easily the lungs can be inflated and deflated
What does lung compliance depend on?
The elasticity of the lungs and the surface tension in the alveoli
What affect does surface tension have on the alveoli?
Alveoli with larger radius have a lower pressure. Gas will diffuse down the concentration gradient. Smaller alveoli will collapse
How do alveoli not collapse from surface tension?
Alveolar type 2 cells secrete surfactant. this stops air moving into the larger alveoli down the pressure gradient and stops the alveoli from collapsing (arms stop from closing completely)
