Diaphragm is the most important inspiratory muscle, supplied by C3-5 (phrenic nerves). Abdo content move down and forwards
Increased in chest cavity.External intercostal muscle aids in moving ribs up and forward
Accessory muscles of inspiration does not really do much in normal inspiration. Involved mostly in forced inspiration. (exercise), Scalene muscles to elevate 2 ribs.
Sternomastoids to raise sternum
And the minor role is the alas nasi (flaring of nasal muscles)
Small muscles of neck and head.
IT is a passive. The lungs go back to normal.
Active expiration is found from exercise and it is aided by the abdominal wall muscles which is the most important muscle.
The rectus abdominus, external and internal oblique and trnasverse muscles.
Pushes diaphragm upwards.
Internal intercostals: Opposite action to the external intercostals
Neck and back muscles.
2 Elastic Properties of Lung
Elasticity: Tendency to return to resting volume after distension.
Partly due to the arragnement of tissue fibres of elastin and collagen.
2.1 Surface Tension
Measure of the force acting to pull a liquid's surface molecules together at air-liquid interface.
Accounts for 1/2 recoil of the lungsFollows Laplace Law.
2.2 Mechanics of Breathing
Air deflation and inflation and pressure curve.
maintains lung compliance and the low surface tension
Secreted by Type II alveolar cells.,
Rapid turnover, depleted in regions with no blood flow.
SOme part are hydrophobic and hydrophillic, the repulsive force interfeure with hydrogen bonding between adjacent molecules of water.
Therefore it lower surface tension and increased compliance, it stabilizes alveoli and keep alveoli dry.
Alveolar are interconnected to each other, hence contribute to stability
3 Elastic properties of the Chest Wall
4 Airway Resistance
5 Pressure and gas flow during the respiratory cycle