What is the result of inspiration?
Multiple Choice
An increased alveolar volume causes increased alveolar pressure.
An increased alveolar volume causes decreased alveolar pressure.
A decreased alveolar volume causes increased alveolar pressure.
A decreased alveolar volume causes decreased alveolar pressure.
An increased alveolar pressure causes decreased alveolar volume.
The Correct Answer and Explanation is:
Correct Answer:
An increased alveolar volume causes decreased alveolar pressure.
Explanation
Inspiration, or inhalation, is the process by which air is drawn into the lungs. This process primarily involves the contraction of the diaphragm and the external intercostal muscles, which expand the thoracic cavity. When the thoracic cavity enlarges, it increases the volume of the alveoli, the tiny air sacs in the lungs where gas exchange occurs.
According to Boyle’s Law, which states that pressure and volume of a gas are inversely related (at a constant temperature), increasing the volume of a space decreases the pressure within it. Thus, when alveolar volume increases during inspiration, alveolar pressure decreases below atmospheric pressure.
This pressure difference (lower pressure in the alveoli compared to the outside atmosphere) creates a pressure gradient that drives air into the lungs. Air moves from an area of higher pressure (outside the body) to an area of lower pressure (inside the alveoli), allowing fresh oxygen to enter.
This process is essential for respiration, as it enables oxygen to reach the lungs and diffuse into the blood while allowing carbon dioxide to be expelled during expiration. Once air enters the alveoli and gas exchange occurs, the diaphragm and intercostal muscles relax, the thoracic cavity returns to its original size, alveolar volume decreases, and pressure increases, pushing air back out.
To summarize:
- Inspiration increases alveolar volume.
- According to Boyle’s Law, this decrease in pressure facilitates air entry.
- The correct physiological result of inspiration is: An increased alveolar volume causes decreased alveolar pressure.
Understanding this mechanism is crucial in fields like medicine, respiratory therapy, and biology because it explains the fundamental process of how breathing works and how ventilation is regulated in the body.
