 The function of the respiratory system is gas exchange. It makes sure the body has a steady supply of oxygen while it disposes of carbon dioxide.

 Ventilation: exchange of gases between the outside and the lungs   External respiration: exchange of gases between the lungs and the blood   Internal respiration: exchange of gases between the blood and the tissues   Cellular respiration: reaction of oxygen and glucose to produce energy, water and carbon dioxide

 Nasal Cavity: Space inside the nose  Pharynx: Joint passage for air and food  Epiglottis: Flap of tissue that prevents objects from entering trachea  Trachea: Semi-rigid tube lined with rings of cartilage

 Larynx: the voice box  Alveoli: Site of gas exchange (external respiration)  Diaphragm: Dome-shaped muscle used in breathing

 Ventilation is the exchange of gases between the outside and the lungs. During inhalation, the diaphragm (and intercostal muscles) contract. This increases the volume of the lungs. The pressure inside the lung drops and air moves into the lungs.   During exhalation, the diaphragm relaxes. This decreases the volume of the lungs. The air pressure inside the lungs increases and air moves out.

 Asthma: narrowing of the bronchi causes coughing wheezing and difficulty breathing  Tuberculosis: bacterial infection causing fever, sweats and spitting blood  Bronchitis: lung infection causing coughing, mucus production, narrowing of bronchi  Pneumonia: lung infection in which alveoli become filled. Cough and chest pain  Rhinitis: inflammation of the mucous membrane of the nose