Question

The average breathing rate of human beings

A) 12-16 times per minute

B) 15-25 times per minute

C) 10-20 times per minute

D) None of the above

Answer 1

Hint: The process of breathing involves two stages: inspiration in which atmospheric air is taken in and expiration in which alveolar air is released outside. The average breathing rate of other mammals like a rabbit is 30-60 breaths per minute.

Complete answer:

Breathing occurs in humans by creating a pressure difference between the atmosphere and inside the lungs. During inhalation, the volume of the lungs increases thus allowing air to move from outside to inside the lungs. During exhalation, the volume of the lungs decreases thus forcing air to move from the lungs to the outside. This process of inspiration and expiration occurs 12-16 times per minute.

Therefore, The average breathing rate of human beings is 12-16 times per minute. So, the correct option is option (A).

Additional Information: 

Breathing is part of respiration which includes many more processes than just inhalation and exhalation of air. All the processes of respiration are mentioned as follows:

- First step includes breathing by which there is an exchange of gases with the environment.

- Second step involves the exchange of these gases across the alveolar membrane.

- Now the gases are transported through the blood.

- The exchange of gases takes place between the blood and tissue cells.

- Lastly, $O_2$ is utilized in the tissue for the catabolism of food resulting in the release of $CO_2$.

Note: 

- Any rate which is above or below the average rate of breathing is indicative of some illness related to the respiratory system.

- Spirometer is an instrument used for the clinical assessment of the functioning of the lungs as it measures the volume of air involved in breathing.

- The volume of air that is inhaled or exhaled during normal respiration is known as tidal volume and its value is 500 mL. This means a normal man inspires 6000-8000 mL of air in one minute.