Grade 8 Biology Practice Test 2025 – Complete Exam Prep

The diaphragm plays a crucial role in the respiratory system by assisting in the expansion and contraction of the lungs during the breathing process. When the diaphragm contracts and flattens, it increases the volume of the thoracic cavity. This reduction in pressure allows air to be drawn into the lungs, a process known as inhalation. Conversely, when the diaphragm relaxes and arches upward, it decreases the thoracic cavity's volume, which increases pressure in the lungs, pushing air out during exhalation.

This process is integral to effective respiration, as it helps maintain the flow of oxygen into the body and carbon dioxide out of it. The diaphragm is essentially a muscle that acts as the primary driver of breathing, working in coordination with other muscles and structures in the respiratory system.