Question

Mark the true statement among the following with reference to normal breathing.
(a) Inspiration is a passive process whereas expiration is active.
(b) Inspiration is an active process whereas expiration is passive
(c) Inspiration and expiration are active processes
(d) Inspiration and expiration are passive processes

Answer 1

Hint: The processes of inspiration and expiration are vital for providing oxygen to tissues and removing carbon dioxide from the body. The action of the inspiratory muscles results in an increase in the volume of the thoracic cavity. The relaxation of the inspiratory muscles results in a decrease in the volume of the thoracic cavity.

Complete step by step answer:
Inspiration is the process by which fresh atmospheric air enters into the alveoli of the lungs, it is an active process and is brought about by the activity of inspiratory muscles. Expiration is the process by which foul air is expelled out of the lungs. Expiration is a normal passive process that involves the relaxation of inspiratory muscles.
So the correct answer is ‘ Inspiration is an active process whereas expiration is passive’.

Additional information:
Inspiration: Inspiration is the flow of air into an organism from the external environment, through the airways, and into the alveoli in the human.
Inspiration begins with the onset of a contraction of the diaphragm, which results in the expansion of the thoracic and pleural cavities and a decrease in pressure (also called an increase in negative pressure).
There are many accessory muscles involved in inhalation—such as external intercostal muscles, scalene muscles, the sternocleidomastoid muscle, and the trapezius muscle.
Breathing just with the accessory muscles rather than the diaphragm is viewed as wasteful, and gives considerably less air during the inward breath.
The negative pressure in the pleural cavity is sufficient to hold the lungs open disregarding the inherent elasticity of the tissue. The thoracic depression increments in volume causing a drop in the pressure (a partial vacuum) inside the lung itself.
As long as the pressure within the alveoli is lower than atmospheric pressure, air will continue to move inwardly, but as soon as the pressure is stabilized air movement stops.
Exhalation:In humans, exhalation is the movement of air out of the bronchial tubes, through the airways, to the external environment during breathing.
Due to the elastic properties of the lungs, it considered the passive process.
During forced exhalation, internal intercostal muscles lower the rib cage and decrease the thoracic volume while the abdominal muscles push up on the diaphragm which causes the thoracic cavity to contract.
Relaxation of the thoracic diaphragm causes contraction of the pleural cavity which puts pressure on the lungs to expel the air.

Note: Breathing patterns consist of tidal volume and respiratory rate in an individual. A normal breathing example is 12 breaths for each moment and 500 mL for every breath. Eupnea is normal breathing at rest. The mechanism of the generation of the ventilatory pattern involves the integration of neural signals by respiratory control centers in the medulla and pons.