Anatomy of lungs

• The lungs are essential respiratory organs located in the thoracic cavity, flanking the heart and mediastinum.

• They are primarily responsible for the exchange of oxygen and carbon dioxide between the air we breathe and the bloodstream.

Structure of lungs

• The anatomy of the lungs is both complex and beautifully designed to maximize their function in gas exchange.

External Anatomy

1. Number and Position:

• Humans have two lungs, a right lung and a left lung, housed within the ribcage.

• The right lung is slightly larger and has three lobes, while the left lung has two lobes to accommodate the heart's position.

2. Lobes:

• The right lung is divided into three lobes: the superior, middle, and inferior lobes, separated by the horizontal and oblique fissures.

• The left lung has two lobes: the superior and inferior lobes, separated by the oblique fissure.

3. Pleura:

• Each lung is encased in a protective double-layered membrane called the pleura.

• The visceral pleura directly covers the lung surface, and the parietal pleura lines the inner chest wall and diaphragm.

• The space between these layers, the pleural cavity, contains a small amount of lubricating fluid that allows the lungs to move smoothly during respiration.

4. Hilum:

• The medial surface of each lung has an opening called the hilum, through which the bronchi, blood vessels, lymphatic vessels, and nerves enter and exit the lung.

Internal Anatomy

1. Bronchial Tree:

• The trachea divides into right and left main bronchi, which further branch into lobar and segmental bronchi, then into smaller bronchioles, ending in terminal bronchioles.

2. Alveoli:

• Terminal bronchioles connect to alveolar ducts, ending in alveolar sacs containing alveoli, where gas exchange of oxygen and carbon dioxide occurs across a thin capillary network.

3. Blood Supply:

• Bronchial arteries supply oxygenated blood to lung tissue, while pulmonary arteries bring deoxygenated blood for oxygenation.

• Oxygenated blood then returns to the heart via pulmonary veins.

4. Lymphatics and Nerves:

• The lungs feature a comprehensive lymphatic system for fluid removal and immune defense, with the pulmonary plexus providing nerve supply for bronchial regulation.

Function in Respiration

1. Ventilation: The mechanical process of moving air into and out of the lungs, facilitated by the diaphragm and intercostal muscles.

2. Gas Exchange: Occurs in the alveoli, where oxygen diffuses into the blood, and carbon dioxide diffuses out to be expelled.