What is the main function of the diaphragm in respiration?

The main function of the diaphragm in respiration is to contract and move downward during inspiration (inhalation). When the diaphragm contracts, it increases the volume of the thoracic cavity, leading to a decrease in internal pressure relative to the outside atmosphere. This pressure difference causes air to flow into the lungs, facilitating the process of breathing.

The diaphragm's movement is essential for effective ventilation; it is the primary muscle responsible for generating the negative pressure needed to draw air into the lungs. This action is crucial for the process of gas exchange, allowing oxygen to enter the bloodstream and carbon dioxide to be expelled from the body.

Understanding how the diaphragm functions provides insight into basic respiratory mechanics and highlights its importance in maintaining efficient breathing. Functions related to heart rate or regulating body temperature are not directly tied to the diaphragm's role in respiration, which makes it clear why the contraction and downward movement of the diaphragm is the correct answer.