Pranayama and Respiratory Functions
The lungs and the unit structure
alveolous are elastic in nature, which due to the action of respiratory
muscles and the diaphragm. In normal respiration, in inspiration the air
fills the alveoli and oxygen is taken up and carbon-di-oxide is expelled
out. But there is residual air containing CO2 in the alveoli. This
residual air dilutes the oxygen content of air we breathe in, in the
next cycle of respiration.
The exchange of gases (O2 and C02)
depends on :
Basically in Pranayama there are
four
steps:
1. Deep inspiration, known as Purak,
where fresh air is taken inside. 2. Holding of the breath, Kumbhak, 3.
Expiration of breath, Rechak, where the air from the lungs (alveoli) is
thrown out through the nose or mouth; it may produce sound variations,
4. After full expiration, holding of breath is called as Shunyak.
Their ration in time frequency is roughly
about 4:2:5:2.
In Purak, i.e. in deep
inspiration, the unit structure alveolus gets stretched so the more surface
area is made available for the absorption of O2 abd giving out of CO2.
In Kumbhak, i.e. holding og
breath after inspiration, the inspired air remains for longer duration of time
in alveoli so that more time is available for the exchange and diffusion of
gases.
In Rechak, i.e. long
expiration with
sound in throat, the air is expelled more effectively and while making
sound in the throat the respiratory muscles, accessory muscles of the
respiration, and diaphragm are put in extra action resulting in complete
expulsion of air from alveoli. Hence when fresh air is taken in, in the
next breath oxygen concentration in the alveoli is not diluted due to
residual gases.
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