The respiratory tract

Also known as the airways.
This includes the larynx, trachea, bronchi, bronchioles, and the lungs.

 

Anatomy

• Air enters the body through the mouth and nose.
• The nasopharynx descends to the oropharynx. The oropharynx descends to become the laryngopharynx.
• The laryngopharynx descends to the larynx.
• The epiglottis sits above the larynx. This is a piece of cartilage which can be pulled down by muscles to act as a laryngeal lid during swallowing.
• The larynx can protect the trachea by closing the vocal folds.
• The trachea splits into 2 primary bronchi.
• The right bronchi splits into 3 secondary bronchi. The left bronchi splits into 2 secondary bronchi.
• In the right lung, there are 10 tertiary bronchi. In the left lung, there are 8-10 tertiary bronchi.
• Beyond tertiary bronchi, the airways become bronchioles. This would be impractical to illustrate here as they are numerous and small. 
• At the terminal end of the respiratory tree, the bronchioles reach alveoli. These are expandable sacks which are inflated with air during inspiration.

Schematic of the respiratory tract. Red = upper lobe, orange = middle lobe, yellow = lower lobe.
Drawn with guidance from the schematic by Dr. Jonathan Simmonds M.D.

 

Pathology

• Ludwig’s angina
• Peritonsillar abscess
• Retropharyngeal abscess
• Foreign body aspiration
• Epiglottitis
• Laryngomalacia
• Laryngeal papillomatosis
• Laryngotracheal stenosis
• Laryngotracheobronchitis
• Bronchiectasis
• Whooping cough
• Asthma 
• Bronchiolitis
• Chronic obstructive pulmonary disease