Question

Explain the process of inspiration under normal conditions.

Answer 1

Hint: Inspiration or inhalation involves taking in air from the atmosphere by creating a pressure gradient between the lungs and the atmosphere.

Complete answer: We breathe! We inhale and exhale the air and this process derives another important process called cellular respiration. How exactly? Well, when we breathe in, we take the oxygen inside, which is transported to the different parts of the body via the blood. It is used by the cells to oxidize the food in the presence of the oxygen and release carbon dioxide in the process. Carbon dioxide is transported back to the lungs and we exhale it out.

So let’s understand what all happens when we inspire or inhale the air. Inspiration involves filling up the lungs with the air. It is initiated by the contraction of the following two muscles:
1) The diaphragm, a thick muscular band present at the base of the chest cavity, contracts and flattens towards the abdominal cavity. This creates volume in the chest cavity.
2) External intercostal muscles contract and elevate the ribs and sternum, further contributing to the increment in the volume of the chest cavity.

Now, bringing the concept of Boyle’s law here, when the volume increases, the pressure decreases. So, the decreased pressure in the thoracic or chest cavity with respect to the atmospheric pressure creates a pressure gradient, that low pressure in the lungs and high pressure in the atmosphere. The air moves from high pressure to low pressure and that’s how we draw the air inside. This finishes the process of inhalation or inspiration.

Note: The process of exhalation is the reverse of the inhalation process. It involves decreasing the volume of the chest cavity so that the pressure of the chest cavity is made high. Air will now move out from the lungs to the atmosphere.