Ans. Human beings have a significant ability to maintain and moderate the respiratory rhythm to suit the demands of the body tissue. This is done by the neural system. 
Respiration regulated by neural system in following ways/ manress
(i) A specialised centre present in the medulla region of the brain called respiratory rhythm centre is primarily responsible in regulating respiration process. Another centre present in the pons regionof the brain called pneumotaxic centre, can moderate the functions of the respiratory rhythm centre. Neural signal from this centre, can reduce the duration of inspiration and there by alter the respiratory rate.
(ii) A chemosensitive areais situated adjacent to the rhythm centre whichis highly sensitiveto carbondioxide and hydrogenions. Increase in these substances activates this centre, which in turn signals the rhythm centre to make necessary adjustments in the respiratory process by which these substances can be eliminated.

(iii) Receptors associated with aortic arch andcarotid artery also recognise changes in carbondioxide and H plus concentration and send necessary signals to the rhythm centre for remedial action because the role of oxygen in the regulation of respiratory rhythm is quite insignificants.