Pathoimmunology Of Airway Diseases (Knoell)

Cigarette smoking is the primary cause of chronic obstructive pulmonary disease (COPD). Long-term exposure to tobacco smoke damages the airways and lungs, leading to inflammation and narrowing of the air passages. This results in symptoms such as coughing, wheezing, and shortness of breath. Smoking is responsible for about 90% of COPD cases, making it the most significant risk factor for developing the disease. Quitting smoking is crucial in preventing and managing COPD, as it can slow down the progression of the disease and improve lung function.

The correct answer is "all of the above are predisposing factors." This means that all of the listed factors, including history of atopy/exposure to airborne allergens, initiation of asthma in early life, respiratory viral infections, and positive family history, are commonly associated with asthma as predisposing factors.

Emphysema is a chronic lung condition that is characterized by the destruction of the air sacs in the lungs, leading to difficulty in exhaling air. This results in the lungs being unable to fully empty, causing air to become trapped in the lungs. This trapped air leads to hyperinflation of the lungs and a decrease in lung elasticity. These changes in the lungs cause an obstructive pattern, where there is difficulty in exhaling air. Therefore, emphysema is correctly matched with the term "obstructive chest condition".

The hygiene theory suggests that the increasing prevalence of atopic diseases can be attributed to a lack of exposure to infectious agents during childhood. According to this theory, when the immune system is not adequately stimulated by pathogens, it becomes more prone to developing allergic reactions. In the context of atopic diseases, TH2 cells are believed to play a predominant role. TH2 cells are responsible for promoting the production of antibodies, specifically IgE, which are involved in allergic responses. Therefore, for an atopic disease to develop, TH2 cells must be more abundant than TH1 cells.

The bronchial morphology of an asthmatic includes inflammation, eosinophils, gland hyperplasia, and hypertrophy of the muscle layer. These changes contribute to the narrowing of the airways and increased mucus production, leading to symptoms such as wheezing and difficulty breathing. However, weakened or collapsed alveolar sacs are not typically seen in asthma. Alveolar sacs are structures in the lungs responsible for gas exchange, and their weakening or collapse is more commonly associated with conditions like emphysema.

The release of chemotactic factors from mast cells is associated with the Late phase reaction (LPR) of mast cell activation. Chemotactic factors are substances that attract and guide immune cells to the site of inflammation or infection. In the Late phase reaction, mast cells release these factors, which then attract other immune cells to the site, amplifying the immune response and promoting inflammation. This response occurs after the initial Early phase reaction and is responsible for the prolonged symptoms and tissue damage seen in conditions such as asthma and allergic reactions.

The statement is false because COPD (Chronic Obstructive Pulmonary Disease) is not on a death decline like coronary heart disease and strokes. While effective treatments have been developed for COPD, it is still a progressive and incurable disease that can lead to severe complications and death. The prevalence and mortality rates of COPD have been increasing globally, making it a significant public health concern. Therefore, it is incorrect to claim that COPD is on a death decline due to the development of effective treatment.

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Gas exchange during respiration requires an even match between blood perfusion and ventilation (air movement). Blood perfusion refers to the flow of blood through the pulmonary capillaries, allowing for the exchange of oxygen and carbon dioxide. Ventilation, on the other hand, refers to the movement of air in and out of the lungs, which ensures that fresh oxygen is brought in and carbon dioxide is expelled. Both parameters need to be balanced in order for efficient gas exchange to occur.

An FEV1/FVC ratio below 70% indicates airflow limitation that is not fully reversible. This means that even after a bronchodilator challenge, the airflow limitation remains. This is a characteristic feature of chronic obstructive pulmonary disease (COPD), which is a progressive lung disease. The other options, such as a 12% improvement in FEV, an FEV1/FVC ratio above 80%, and a 200 ml change in spirometry, do not necessarily indicate irreversible airflow limitation.

TH1 lymphocytes are not a major player in perpetuating tissue damage and inflammation related to asthma. Asthma is primarily driven by an allergic response, which involves the activation of TH2 lymphocytes. TH1 lymphocytes, on the other hand, are involved in cell-mediated immune responses and play a role in fighting intracellular pathogens. While inflammation can occur in asthma, it is mainly driven by the release of inflammatory mediators from mast cells, TH2 lymphocytes, eosinophils, and neutrophils.

Eosinophils are a type of granulocyte that are very potent and persist in circulation for 8-12 hours. Their presence in the lung, skin, or internal organs is indicative of disease. Neutrophils are also granulocytes, but they have a shorter lifespan and are not specifically associated with these locations. Mast cells are not granulocytes and are primarily found in tissues, not in circulation. Dendritic cells are not granulocytes and have a different function in the immune system. Phagocytes is a general term that includes various types of cells, including neutrophils and eosinophils, but it does not specifically fit the given description. Therefore, the correct answer is eosinophils.

Dendritic cells are able to recognize invaders with higher specificity through their specialized receptors. They can phagocytose the bacterium, meaning they can engulf and destroy it. Dendritic cells also have the ability to process antigens, breaking them down into smaller pieces and presenting them on their cell surface. Finally, dendritic cells can mobilize to regional lymph nodes to present antigens to lymphocytes, which is crucial for initiating an immune response.