Question

The average lung capacity is
A. 7 litres
B. 6 litres
C. 9 litres
D. 5 litres

Answer 1

Hint: The lungs are the paired structures that are seen in the thoracic cavity. The thoracic cavity is an airtight chamber that helps in normal breathing. The exchange of gases takes place inside the lungs while breathing.

Step by step answer:Respiration is the term used for the whole process starting from intake of air to the production of energy in the form of ATP inside cells. Breathing is the first step in respiration. It is also called pulmonary ventilation. Breathing has two steps. They are inspiration and expiration. Inspiration takes place when air enters the thoracic cavity and expiration happens when air is released from it. Inspired air reaches the lungs and the oxygen present in it is exchanged with carbon dioxide. It happens inside small sac-like structures present inside the lungs called alveoli. A spirometer is an instrument that helps to measure the volume of air in breathing. Tidal volume is the amount of air that is inspired or expired during normal respiration. Inspiratory reserve volume is the additional volume of air that a person can breathe in by forced inspiration. Expiratory reserve volume is the additional volume of air that a person can expire using forced expiration. A person can’t eliminate an entire volume of air even by forced expiration. The amount of air left in the lungs even after forced expiration is called residual volume. Total lung capacity is the total amount of air present in the lungs at the end of forced inspiration. It is the sum of TV, IRV, ERV, and RV. In a normal healthy person, average lung capacity will be about 6 litres.
Hence, the correct option is B

Note: Several pulmonary capacities by adding respiratory volumes. These are clinically important as it helps to find abnormal conditions. They are inspiratory capacity, expiratory capacity, vital capacity, functional residual capacity, and total lung capacity.