The document describes the human respiratory system including its main parts like the nose, trachea, lungs and diaphragm. It explains that the respiratory system brings air into the body through the nose and mouth, filters and conditions the air in the nasal passages, and then transports the air through the trachea, bronchi and bronchioles to the alveoli in the lungs where gas exchange occurs. Each part of the respiratory system plays an important role in this breathing process to deliver oxygen to the body and remove carbon dioxide.