Physiology of respiration-2

Respiration in Relation to Boyle's Law

The thoracic cavity's volume changes, which are a necessary part of breathing, are entirely mechanical. Remembering the rule that volume changes cause pressure changes, which cause gas flow to equalize the pressure, is important. Boyle's Law describes the link between a gas's temperature, pressure, and volume.

Chemist and physicist Robert Boyle, an Anglo-Irish, lived from 1627 to 1961. For Boyle's law, he is best known. An experimental gas law explains how a gas's pressure tends to rise when the volume of the container shrinks. Boyle's law is stated as follows: "If the temperature and quantity of the gas remain constant within a closed system, the absolute pressure exerted by a given mass of an ideal gas is inversely proportional to the volume it fills. Boyle's law can be expressed mathematically as pressure is inversely proportional to volume.

This means that, for a given temperature, an increase in volume results in a decrease in both atmospheric pressure and the pressure of the gas inside the container. Conversely, a decrease in volume results in an increase in atmospheric pressure. Additionally, as a closed container's size increases, the pressure of the gas inside decreases, and conversely, as a closed container's size decreases, the pressure inside rises.

The law also holds true for breathing. According to Boyle's law, the mechanism of respiration explains that when the body's temperature stays constant, the respiratory muscles' contraction causes the volume of the thoracic cavity to increase. The effect is that the lungs enlarge and their volume rises. Air pressure in the lungs simultaneously drops in compared to ambient air pressure. This enables the movement of atmospheric air into the lungs, resulting in inspiration. The thoracic cavity's volume decreases during expiration as a result of the diaphragm rising and the intercostal muscles descending. Air is forced out of the lungs as the volume decreases due to increased pressure inside the lungs. Thus, expiration takes place.