The document describes the major parts of the respiratory system and their functions. It starts with the nose which warms, filters, and moistens air before it reaches the pharynx or throat. The larynx or voicebox contains the epiglottis that closes during swallowing. The trachea or windpipe delivers air to the lungs which are made of lobes and exchange oxygen and carbon dioxide with blood through external and internal respiration involving the diaphragm and intercostal muscles. Several respiratory diseases are also mentioned.