Question

Abhirami runs to her class rooms as the school ball rang. What will be the probable rate of breathing in her lungs due to this vigorous act?

• A. 15 to 18 times per minute
• B. 16 to 20 times per minute
• C. 18 to 25 times per minute
• D. 20 to 25 times per minute

Answer 1

The correct option is D 20 to 25 times per minute

As exercise intensifies and the body’s need for fresh oxygen increases, the ventilation rate responds accordingly. The metabolic byproducts of exercise build up as a result of cellular respiration, and the amount of carbon dioxide (CO${}_2$) in the system also increases to act as a buffer against these acidic byproducts. As the concentration of CO${}_2$ increases, the body responds by breathing deeper and more frequently to dispel the CO${}_2$. Working muscles also require fresh oxygen. The rate of respiration also increases to facilitate the delivery of oxygen to the bloodstream, where it is then transported to the working muscles. The rate at which cellular respiration takes place (and hence oxygen is consumed) varies with the general state of activity of the body. Vigorous exercise may increase by 20 to 25 times the demands of the tissues for oxygen. This increased demand is met by increasing the rate and depth of breathing.

Therefore, the correct answer is option D.