The lungs are vital organs in the respiratory system, exchanging oxygen (O2) and carbon dioxide (CO2) between the blood and the air. Understanding their anatomy is crucial for comprehending their function and how they support respiration.
1. Lobes:
•Each lung is divided into lobes. The right lung has three lobes: the upper, middle, and lower lobes, while the left lung has two lobes: the upper and lower lobes. These lobes are separated by fissures, which are deep clefts or folds in the lung tissue.
2. Bronchial Tree:
•The bronchial tree is a branching system of air passages that delivers air to the lungs. It begins with the trachea (windpipe), which bifurcates into the right and left primary bronchi, one entering each lung. These primary bronchi further divide into smaller secondary bronchi and even smaller ones. This branching continues until it reaches the smallest airways, called terminal bronchioles.
3. Alveoli:
•Alveoli are tiny, thin-walled air sacs located at the terminal ends of the bronchioles. They are the primary sites for gas exchange. Each lung contains millions of alveoli, greatly increasing the surface area for gas exchange. Oxygen diffuses from the alveoli into the bloodstream, while carbon dioxide moves into the alveoli to be exhaled.
4. Pleura:
•The lungs are enclosed by a double-layered membrane known as the pleura. The visceral pleura is the inner layer, adhering to the lung’s surface, while the parietal pleura lines the chest wall and diaphragm. The pleural space between these two layers contains a small amount of lubricating fluid, allowing the lungs to move smoothly within the chest during breathing while minimizing friction.
5. Diaphragm:
•The diaphragm is a dome-shaped, muscular sheet separating the thoracic and abdominal cavities. It plays a vital role in breathing. When it contracts, it flattens, increasing the volume of the thoracic cavity and causing inhalation. When it relaxes, it returns to its dome shape, decreasing the thoracic cavity volume and causing exhalation.
Right and Left Lungs
The right lung has three lobes: an upper, middle, and lower. The right lung usually weighs 155–720 gm in males and 100–590 gm to in females.
The left lung has two lobes – an upper and lower lobes. It does not have a middle lobe like the right lung. It weighs between 110 – 675 gm in men and 100– 590 gm in women.
