Air sacs or grape-like clusters found at the end of each bronchiole.

The trachea divides into two branches called bronchi. Each bronchus leads to a separate lung.

Thin hairs located just inside the nostril, filtering incoming air to remove debris.

Muscle separating the chest and abdomen, aids in breathing.

Flap of cartilage that covers the larynx or voice box.

Voice box. The larynx contains structures that make speech possible.

There are two lungs, the right having three lobes: the superior, middle and inferior; the left having two lobes: the superior and inferior. The upper part of the lung is called the apex; the lower portion is called the base.

The nasal cavity is the passageway for air to enter the body. A wall of cartilage called the nasal septum divides the nose. The nose is lined with mucous membrane. Mucus, which is secreted by the mucous membrane helps to moisten, warm and filter the air as it enters the nose.

Four pairs of sinuses located in the bones of the skull communicate with the nasal cavity. The paranasal sinuses are the maxillary, ethmoid, frontal and sphenoid.

Throat. The pharynx has three divisions: nasopharynx, oropharynx and laryngopharynx.

Multi layered membrane surrounding each lung. There are three layers: the parietal (outer layer), visceral (inner layer) and the pleural space (pleural cavity) containing a lubricating fluid to prevent friction when the membranes rub together during respiration.

Area containing the lungs. The region between the lungs is called the mediastinum and it contains the heart, aorta, esophagus, trachea, bronchial tubes and thymus.

Loss of the ability to produce normal speech sounds.

Interruption of breathing that may result in loss of consciousness or death.

Slow rate of respiration (less than 10 breaths per minute).

Acute respiratory syndrome in children and infants characterized by obstruction of the larynx, hoarseness and a barking cough.

Bluish discoloration of the skin caused by lack of oxygen.

Inherited disease of the exocrine glands leading to airway obstruction.

Progressive loss of lung function caused by enlargement of the alveoli. As they enlarge, the alveoli become less elastic, lose their ability to expel air and eventually rupture. Breathing becomes increasingly rapid, shallow and difficult.

Also known as pyothorax. Accumulation of pus in the pleural cavity.