The respiratory system consists of organs responsible for breathing in oxygen and breathing out carbon dioxide. It includes the nasal cavity, pharynx, larynx, trachea, lungs, and diaphragm. The nasal cavity filters air and the lungs exchange gases via alveoli and capillaries. Oxygen is absorbed into the bloodstream in the alveoli and carried throughout the body, while carbon dioxide is released from the blood into the alveoli to be breathed out.