Question

The respiratory system (involving inhalation and exhalation processes) is responsible for taking in oxygen-rich air and expelling carbon dioxide-rich air. Which of the following is the sequence in which events occur in the inhalation process?
P: Air pressure inside your lungs drops.
Q: The diaphragm contracts.
R: Air from outside rushes into your lungs.
A) P,Q,R
B) Q,P,R
C) R,P,Q
D) Q, R, P

Answer 1

Hint:The breathing mechanism in humans involves inspiration and expiration. Inspiration is the process in which the diaphragm contracts, the chest cavity enlarges, and the air pressure inside our lungs drops. To equalize pressure air from outside rushes into our lungs.

Complete answer:
The primary organ of the respiratory system is the lungs. They help us to inhale the oxygen and exhale carbon dioxide. This is the process of exchange and it is called respiration. The human body doesn't require carbon dioxide, hence it needs to be exhaled out. This process of breathing out carbon dioxide is known as exhalation. In the question, it is being asked about inhalation, the steps which take place at the time we inhale the oxygen. The first step obviously in the process of inhalation taking in the air which contains oxygen. Diaphragm is an organ that is present beneath the chest cavity and it contracts when the air is inhaled and relaxes when air is not being inhaled or at the time of exhalation. Therefore, the second step of inhalation is the contraction of diaphragm, and finally, the air pressure inside the lungs drops. Alveolar pressure is the pressure of the air inside the lung alveoli. So, during inspiration, the increased volume of alveoli decreases the alveolar pressure.

Hence the correct answer is option ‘C’.

Note: Human body requires oxygen for the processing of various metabolic activities. The oxygenated blood is carried by arteries and deoxygenated blood is carried out by veins. Purification of blood takes place in the lungs. Purified blood from the lungs is then sent to the heart.