Bronchi

Trachea_(transparent)

Respiratory_system_complete

The bronchi are the main passageway into the lungs. The trachea divides into the left and right bronchus, which then branch into smaller tubes, known as bronchioles, that spread throughout each lung. The singular form of bronchi is bronchus. They play a critical role in the respiratory system, conducting air in and out of the lungs.

Structure

The bronchi are made up of cartilage and smooth muscle. They are lined with ciliated epithelium and mucus-secreting glands that help trap and expel foreign particles. The right bronchus is shorter, wider, and more vertical than the left bronchus, making the right lung more susceptible to aspiration of foreign materials.

Primary Bronchi

The trachea divides at the carina into the left and right primary bronchi. Each primary bronchus enters its respective lung to supply it with air. The point of division, known as the bifurcation, occurs at the level of the fifth thoracic vertebra.

Secondary and Tertiary Bronchi

Each primary bronchus divides into secondary (lobar) bronchi, with three on the right (for each lobe of the right lung) and two on the left. These further divide into tertiary (segmental) bronchi, which supply air to specific segments of each lung lobe.

Function

The primary function of the bronchi is to conduct air from the trachea into the lungs. The mucociliary escalator mechanism of their lining helps to keep the airways clear of mucus and dirt, protecting the respiratory system from infection and facilitating efficient gas exchange.

Clinical Significance

• Bronchitis - Bronchitis is an inflammation of the bronchial tubes often caused by infections or other environmental factors like smoking.

• Asthma - Asthma is a chronic condition where the bronchi become inflamed and narrowed, making it difficult to breathe.

• Bronchiectasis - Bronchiectasis involves the permanent enlargement of parts of the airways, leading to excessive mucus production and vulnerability to infection.

• Lung Cancer - Lung cancer can originate from the bronchi, known as bronchogenic carcinoma, which is the most common type of primary lung cancer.

Diagnostic and Therapeutic Procedures

• Bronchoscopy

Bronchoscopy is a procedure that allows doctors to examine the inside of the airways, including the bronchi, for diagnostic and therapeutic purposes.

• Pulmonary Function Tests

Pulmonary function tests (PFTs) assess the functionality of the bronchi along with other components of the respiratory system.

See Also

• Respiratory system
• Trachea
• Lung
• Pulmonary alveolus
• Respiratory disease