the mechanism of breathing Flashcards
what is inspiration (inhalation)?
when the air pressure of the atmosphere is greater than that of the lungs, and air is forced into the lungs.
what is expiration (exhalation)?
when the air pressure of the lungs is greater than that of the atmosphere, and air is forced out of the lungs.
what kind of process is inspiration?
an active process - it uses energy
describe the stages of inspiration/breathing in
the external intercostal muscles contract, the internal intercostal muscles relax.
the ribs are pulled upwards and outwards, increasing the volume of the thorax.
diaphragm muscles contract (it flattens), further increasing the volume of the thorax.
the increased volume of the thorax = reduced pressure in the lungs
atmospheric pressure > pulmonary pressure - air is forced into lungs
describe the stages of expiration/breathing out
the internal intercostal muscles contract, the external intercostal muscles relax.
the ribs are pulled downwards and inwards, decreasing the volume of the thorax.
diaphragm muscles relax, further decreasing the volume of the thorax.
the decreased volume of the thorax = increased pressure in the lungs
atmospheric pressure < pulmonary pressure - air is forced into lungs
what kind of process is expiration?
largely passive process - does not require much energy
what is pulmonary ventilation rate?
the total volume of air that is moved into the lungs in 1 minute
what is tidal volume?
the volume of air normally taken in when the body is at rest - usually around 0.5 dm^3
what is breathing rate?
number of breaths taken in one minute
pulmonary ventilation rate formula
tidal volume (dm^3) x breathing rate (per min)
