What happens anatomically in emphysema؟
إجابة الطالب المختصرة من خلال موقع بوابة الإجابات هي
ب) Destruction of alveolar walls and air trapping
Emphysema is a chronic lung condition characterized by the destruction of the alveoli, the tiny air sacs in the lungs responsible for gas exchange (oxygen in, carbon dioxide out). Here's a breakdown of the anatomical changes:
**1. Destruction of Alveolar Walls:**
* **Enlargement of Air Spaces:** The defining feature of emphysema is the permanent enlargement of the air spaces distal to the terminal bronchioles. This means the alveoli themselves are damaged and broken down.
* **Loss of Interalveolar Septa:** The walls between the alveoli (interalveolar septa) are progressively destroyed. These septa contain capillaries, which are crucial for gas exchange. Their destruction reduces the surface area available for oxygen and carbon dioxide transfer.
* **Reduced Capillary Bed:** As the alveolar walls are destroyed, the capillaries within those walls are also destroyed. This significantly reduces the blood supply available for gas exchange.
**2. Loss of Lung Elasticity:**
* **Reduced Elastic Recoil:** Healthy lungs are elastic, meaning they can stretch during inhalation and recoil passively during exhalation. Emphysema causes a loss of this elasticity. The lungs become floppy and overinflated.
* **Air Trapping:** Because the lungs can't recoil properly, air becomes trapped inside, particularly during exhalation. This leads to hyperinflation of the lungs.
**3. Changes in Airways (Bronchioles):**
* **Collapse of Small Airways:** The loss of alveolar support can cause the small airways (bronchioles) to collapse, particularly during exhalation. This further contributes to air trapping.
* **Increased Airway Resistance:** The collapse of airways and the loss of structural support increases the resistance to airflow.
**4. Hyperinflation of the Lungs:**
* **Increased Total Lung Capacity:** Because air is trapped, the overall volume of air the lungs can hold (total lung capacity) increases.
* **Increased Residual Volume:** The amount of air remaining in the lungs after a maximal exhalation (residual volume) also increases significantly.
* **Barrel Chest:** Chronic hyperinflation can lead to a characteristic "barrel chest" appearance, where the chest diameter increases.
**5. Diaphragm Flattening:**
* **Reduced Diaphragm Efficiency:** The diaphragm, the primary muscle of breathing, flattens out due to the hyperinflated lungs pushing downwards. This reduces its efficiency in pulling air into the lungs.
* **Use of Accessory Muscles:** Individuals with emphysema often rely heavily on accessory muscles in the neck and shoulders to breathe, which is less efficient and more tiring.
**6. Bullae Formation (in some cases):**
* **Large Air-Filled Spaces:** In severe emphysema, large air-filled spaces called bullae can form in the lungs. These bullae don't contribute to gas exchange and can compress surrounding healthy lung tissue.
**In summary:**
Emphysema involves the progressive destruction of the alveoli, leading to a loss of lung elasticity, air trapping, hyperinflation, reduced gas exchange, and eventually, significant breathing difficulties. The destruction of the alveolar walls and capillaries is the key pathological process. This leads to a constellation of anatomical changes that ultimately impair respiratory function.
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