Pathophysiology of asthma

Overview of the pathophysiology of asthma

Illustration of an asthma attack

The pathophysiology of asthma involves complex interactions between genetic predispositions and environmental factors, leading to chronic inflammation of the airways. This inflammation results in airway hyperresponsiveness, airflow obstruction, and characteristic symptoms such as wheezing, coughing, chest tightness, and shortness of breath.

Airway Inflammation

Asthma is primarily characterized by inflammation of the airways. This inflammation is driven by a variety of immune cells, including eosinophils, mast cells, T lymphocytes, and macrophages. These cells release inflammatory mediators such as cytokines, leukotrienes, and histamine, which contribute to the inflammatory process.

Role of Eosinophils

Eosinophils are a key component in the inflammatory response in asthma. They release toxic granules and cytokines that damage the airway epithelium and perpetuate inflammation. The presence of eosinophils in the airways is a hallmark of allergic asthma.

Mast Cells and Histamine Release

Mast cells are activated in response to allergens and release histamine, which causes bronchoconstriction, increased mucus production, and further recruitment of inflammatory cells.

Airway Remodeling

Diagram showing airway changes in asthma

Chronic inflammation in asthma leads to structural changes in the airways, a process known as airway remodeling. This includes thickening of the airway walls, increased smooth muscle mass, and subepithelial fibrosis. These changes contribute to the persistent nature of asthma and can lead to irreversible airflow obstruction over time.

Airway Hyperresponsiveness

Airway hyperresponsiveness (AHR) is a characteristic feature of asthma, where the airways are overly sensitive to various stimuli such as allergens, cold air, and exercise. This hyperresponsiveness is due to the heightened state of inflammation and the structural changes in the airways.

Bronchoconstriction

Bronchoconstriction in asthma

Bronchoconstriction is the narrowing of the airways due to contraction of the bronchial smooth muscle. It is a major cause of the acute symptoms of asthma and is triggered by exposure to allergens, irritants, or physical activity.

Mucus Hypersecretion

In asthma, there is an overproduction of mucus by the goblet cells in the airway epithelium. This mucus can obstruct the airways and exacerbate breathing difficulties during an asthma attack.

Genetic and Environmental Factors

Asthma is influenced by both genetic and environmental factors. Genetic predispositions can affect immune responses and airway structure, while environmental factors such as allergens, pollution, and respiratory infections can trigger and exacerbate asthma symptoms.

Related pages

• Asthma
• Allergy
• Chronic obstructive pulmonary disease
• Respiratory system

Lung tissue affected by asthma