How is respiration regulated?
Human beings have a significant ability to maintain and moderate the respiratory rhythm to suit the demands of the body tissues. This regulation is carried out by the neural system.
A specialised centre present in the medulla region of the brain called the respiratory rhythm centre is primarily responsible for this regulation. It maintains the basic rhythm of breathing according to the body's requirements.
Another centre present in the pons region of the brain called the pneumotaxic centre can moderate the functions of the respiratory rhythm centre. Neural signals from this centre can reduce the duration of inspiration and thereby alter the respiratory rate.
A chemosensitive area is situated adjacent to the rhythm centre which is highly sensitive to CO₂ and hydrogen ions. Increase in these substances can activate this centre, which in turn signals the rhythm centre to make necessary adjustments in the respiratory process by which these substances can be eliminated.
Receptors associated with aortic arch and carotid artery also recognise changes in CO₂ and H⁺ concentration and send necessary signals to the rhythm centre for remedial actions. The role of oxygen in the regulation of respiratory rhythm is quite insignificant.
Explanation
This answer covers all the key aspects of respiratory regulation from the NCERT textbook: (1) the primary role of respiratory rhythm centre in medulla, (2) the moderating role of pneumotaxic centre in pons, (3) the chemosensitive area's sensitivity to CO₂ and H⁺, and (4) the peripheral receptors in aortic arch and carotid artery. The answer correctly notes that oxygen plays an insignificant role in regulation, which is an important point students often miss.