The organ primarily responsible for breathing is the lungs. They function by taking in oxygen from the air and expelling carbon dioxide, a waste product from the body. Breathing involves two main processes: inhalation, where air fills the lungs, and exhalation, where air is expelled. Additionally, the diaphragm plays a crucial role in this process by contracting and relaxing to assist with airflow. Overall, the respiratory system is vital for providing the body with oxygen needed for cellular metabolism and for removing carbon dioxide to maintain healthy blood pH levels.