Question

Radiographic ( \(x\)-ray) pictures show that the rib cage of a person with a pneumothorax is expanded and the ribs are farther apart. Explain why this should be so.

Short answer

In a person with pneumothorax, air accumulates in the pleural space, disrupting the pressure balance in the chest cavity and preventing the diaphragm from functioning effectively. As a result, the lungs cannot expand properly, and the chest cavity compensates by increasing its volume. This causes the rib cage to expand and the ribs to get farther apart, which can be seen on radiographic (x-ray) pictures.

Step-by-step solution

Understand Pneumothorax

Pneumothorax is a condition where air accumulates in the pleural space, which is the space between the lungs and the chest cavity. This accumulation of air can result from a lung injury or can occur spontaneously. When air accumulates in the pleural space, it separates the lung from the chest wall, making it harder for the lung to inflate and leading to reduced lung capacity.

Role of the diaphragm

In a healthy person, the diaphragm, a dome-shaped muscle located below the lungs, plays a crucial role in the breathing process. When the diaphragm contracts and moves downward, it creates a negative pressure within the chest cavity, causing the lungs to expand and pulling air in. When the diaphragm relaxes and moves upward, the positive pressure within the chest cavity pushes the air out of the lungs.

Pneumothorax effect on the diaphragm and chest cavity

In a person with pneumothorax, the presence of air in the pleural space disrupts this pressure balance, preventing the diaphragm from functioning effectively. This results in the lungs not being able to expand properly, and the chest cavity may try to compensate for the decreased lung capacity by increasing in volume.

Rib cage expansion and ribs getting farther apart

As the chest cavity increases its volume to compensate for the reduced lung capacity, the rib cage expands outward, causing the ribs to get farther apart. This expansion and separation of the ribs can be observed on radiographic (x-ray) pictures of a person with a pneumothorax. In conclusion, the rib cage of a person with a pneumothorax is expanded and the ribs are farther apart because the presence of air in the pleural space disrupts the pressure balance in the chest cavity, leading to a compensatory expansion of the chest cavity.