Mechanism of Breathing
Anatomy of breathing: In normal respiration the air is
taken in through the nostrils, with out any special effort, sound or
exaggerated movement of the nose or chest. In short it is done unconsciously.
We are not even aware of the air travelling through the nostrils, down the nasal
and oral parts of the pharynx, of it’s reaching the larynx and then the trachea
and the lungs. In general, most of us are unaware of how the breathing process
Mechanism of Breathing: How breathing process works?
INSPIRATION: The respiratory centre in the medulla and pons of the mid brain
through the nervous system make few impulses on the respiratory muscles
(diaphragm, intercostals muscles, Pectoralis major, Pectoralis minor, serratus
anterior and scalenii muscles) which makes them contract and when they contract
the rib cage being pulled out ward diaphragm move down ward and collar bone
move upward and along with that pleura moves with the valves of thorax, pulling
the lungs with it out ward in all direction and increasing their volume. The pressure
in the air passages and alveoli decreases thereby drawing air in to lungs in an
attempt to equalize the positive atmospheric pressure and the negative pressure
inside the thoracic cavity. When the muscles of inhalation have completed their
work, what makes the airflow out of the lungs? The answer requires careful
self-observation. If you observe thoroughly on any resting posture, you will
notice that the exhalation naturally follows the end of the inhalation.
Expiration: is usually a passive process. There are no muscles in
the lungs to make air flow out, yet it seems that the lungs contract
spontaneously. Why? The answer to this puzzle lies in the natural elasticity of
the lungs. Relaxation of the diaphragm and intercostals muscles result in
downward and inward movement of the ribcage and elastic recoil of lungs.
Pressure in the lungs now exceeds atmospheric pressure and air is expelled from
the respiratory tract.