The respiratory system is the collection of organs and structures in the body that enable breathing, allowing oxygen to enter the body and carbon dioxide to be expelled. It includes the lungs, nose, mouth, trachea, bronchi, bronchioles, diaphragm, voice box (larynx), throat, and associated muscles and blood vessels

. Its primary function is to facilitate gas exchange: oxygen is inhaled into the lungs, where it passes through tiny air sacs called alveoli into the bloodstream, and carbon dioxide, a waste product from cells, is transferred from the blood to the lungs to be exhaled

. The respiratory system also warms, moistens, and filters the air, protects the airways from harmful particles, and enables speech by passing exhaled air over the vocal cords

. Breathing is achieved by the coordinated contraction and relaxation of the diaphragm and intercostal muscles, which change the pressure in the chest cavity to draw air in and push it out

. The respiratory system works closely with the circulatory system to deliver oxygen to cells and remove carbon dioxide from the body

. In summary, the respiratory system is essential for supplying oxygen to the body’s cells, removing carbon dioxide, protecting the lungs, and enabling speech