(a) In normal breathing which of the following is an active process.
Inspiration or expiration ? Also tell why ?
(b) In normal human how many times normal breathing occurs at rest per minute ?

Explanation

(a) In normal breathing , inspiration is an active process as it is brought about by the diaphragm muscless and external intercostal muscles. Expirtion is normally a passive provess as it simply involves relaxation of the inspiratory muscles.
(b) At rest in a normal human breathing occurs about 14-18 times per minute.