Respiratory.

Capn/o refers to carbon dioxide. Hypocapnia means low carbon dioxide levels. Ox/o refers to oxygen. Hypoxia is low oxygen. Hyperoxia is high oxygen. Hypercapnia (also called hypercarbia) is high carbon dioxide.

Pharyng/o refers to the throat (pharynx). Laryng/o refers to the voice box (larynx). Rhin/o and nas/o both refer to the nose.

The trachea is a continuation of the larynx. It divides into the right and left bronchi. The larynx passes air from the pharynx to the trachea. The pharynx is a tube behind the nose that passes air to the larynx and food to the esophagus. The alveoli are tiny air sacs at the ends of the bronchioles.

The right lung has 3 lobes. The left lung has 2 lobes. The right lung is slightly larger to accommodate three lobes.

Pnea means breath or respiration. Ortho means erect or upright. Orthopnea is breathlessness when lying down that improves in an erect position. The prefix tachy- means fast, so tachypnea is rapid breathing. The prefix a- means absent, so apnea is absence of breathing. The prefix dys- means difficult, so dyspnea is difficult breathing.

Wheezing is a high-pitched whistling sound heard when the airway is blocked. Rales (also called crackles or crepitations) are crackling sounds heard on inspiration when there is fluid in the alveoli. Rhonchi are low-pitched rumbling sounds heard when there are secretions in the airway.

A pulse oximeter measures blood oxygen saturation. A spirometer measures the volume and flow of air in and out of the lungs. It diagnoses asthma and COPD. A bronchoscope visualizes the lungs and airways. A laryngoscope visualizes the larynx.

Another name for whooping cough is pertussis. Croup is a viral infection causing a barking cough, mostly in children. Pneumonia is a lung infection caused by bacteria, viruses, or fungi. Tuberculosis (TB) is a bacterial lung disease caused by Mycobacterium tuberculosis.

Thoracocentesis is the process of removing fluid or air from the pleural space. An incision through the trachea is called a tracheostomy. Visualizing the lungs is bronchoscopy. Placing a tube in the trachea through the mouth is endotracheal intubation.

Obstructive lung diseases cause airway obstruction. They include asthma, chronic bronchitis, and emphysema. Pneumonia, tuberculosis, and croup are all infectious diseases, not obstructive lung diseases.