超急!! bio 1問

Inhalation:
External intercostal muscle contracts (internal: relaxs) → Elevation of the rib cage (1)
Diaphragmatic muscle contracts → Flattening of the diaphragm (2)
(1) + (2) → Volume of thoracic cavity ↑/ Pressure of thoracic cavity ↓ (becomes negative) → Air goes into the lungs

Exhalation:
Internal intercostal muscle contracts (external: relaxs) → Depression of the rib cage (1)
Diaphragmatic muscle relaxs→ Resumption of the dome shape (2)
(1) + (2) → Volume of thoracic cavity ↓/ Pressure of thoracic cavity ↑(becomes positive) → Air goes out of the lungs

上面寫既pressure係postive定係negative，係relative to atmospheric pressure~~

Inhalation (also known as inspiration) is the movement of air from the external environment, through the airways, into the alveoli during breathing.

Inhalation begins with the onset of contraction of the diaphragm, which results in expansion of the intrapleural space and an increase in negative pressure according to Boyle's Law. This negative pressure generates airflow because of the pressure difference between the atmosphere and alveolus. Air enters, inflating the lung through either the nose or the mouth into the pharynx (throat) and trachea before entering the alveoli.

Other muscles that can be involved in inhalation include:

External intercostal muscles
Scalene muscles
Sternocleidomastoid muscle
Trapezius muscle