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Questions and Answers
Which of the following is NOT a characteristic morphologic change in asthma, termed airway remodeling?
Which of the following is NOT a characteristic morphologic change in asthma, termed airway remodeling?
What is the most striking finding in the lungs of individuals who die from severe asthma attacks?
What is the most striking finding in the lungs of individuals who die from severe asthma attacks?
What is the likely cause of aspirin sensitivity in patients with asthma?
What is the likely cause of aspirin sensitivity in patients with asthma?
Which of the following is NOT a common trigger for respiratory infections in asthmatics?
Which of the following is NOT a common trigger for respiratory infections in asthmatics?
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What is the underlying mechanism by which viruses trigger asthma exacerbations?
What is the underlying mechanism by which viruses trigger asthma exacerbations?
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Why is the treatment for atopic and nonatopic asthma similar?
Why is the treatment for atopic and nonatopic asthma similar?
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What is the primary mechanism responsible for dyspnea and wheezing in an asthma attack?
What is the primary mechanism responsible for dyspnea and wheezing in an asthma attack?
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What is the connection between occupational asthma and the inciting antigen?
What is the connection between occupational asthma and the inciting antigen?
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Based on the provided information, which of the following is NOT a proposed contributing factor to the development of asthma?
Based on the provided information, which of the following is NOT a proposed contributing factor to the development of asthma?
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Which of the following patterns of inflammation is described as the MOST COMMON in the provided information regarding asthma?
Which of the following patterns of inflammation is described as the MOST COMMON in the provided information regarding asthma?
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Which statement is TRUE about the hygiene hypothesis in relation to asthma?
Which statement is TRUE about the hygiene hypothesis in relation to asthma?
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What is the primary reason for the increased incidence of asthma in affluent countries, according to the provided information?
What is the primary reason for the increased incidence of asthma in affluent countries, according to the provided information?
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Which of the following is NOT a hallmark of asthma, as presented in the content?
Which of the following is NOT a hallmark of asthma, as presented in the content?
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A patient presents with symptoms of wheezing, breathlessness, and chest tightness, primarily at night. The patient's medical history includes a family history of allergies and a prior diagnosis of allergic rhinitis. Based on the provided content, which type of asthma is this patient most likely experiencing?
A patient presents with symptoms of wheezing, breathlessness, and chest tightness, primarily at night. The patient's medical history includes a family history of allergies and a prior diagnosis of allergic rhinitis. Based on the provided content, which type of asthma is this patient most likely experiencing?
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What is the most likely reason for the reversible nature of airway obstruction in asthma?
What is the most likely reason for the reversible nature of airway obstruction in asthma?
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Which of the following mediators released from mast cells triggers bronchoconstriction in the early phase of an allergic reaction?
Which of the following mediators released from mast cells triggers bronchoconstriction in the early phase of an allergic reaction?
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What is the primary role of IL-5 in the pathogenesis of atopic asthma?
What is the primary role of IL-5 in the pathogenesis of atopic asthma?
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What is the primary difference between atopic and nonatopic asthma?
What is the primary difference between atopic and nonatopic asthma?
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Which of the following is NOT a characteristic of airway remodeling in asthma?
Which of the following is NOT a characteristic of airway remodeling in asthma?
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What is the role of Charcot-Leyden crystals in asthma pathogenesis?
What is the role of Charcot-Leyden crystals in asthma pathogenesis?
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Which of the following is NOT a characteristic of the late-phase reaction in asthma?
Which of the following is NOT a characteristic of the late-phase reaction in asthma?
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Which of the following best describes the role of IgE in atopic asthma?
Which of the following best describes the role of IgE in atopic asthma?
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Which of the following events is NOT directly involved in airway remodeling in asthma?
Which of the following events is NOT directly involved in airway remodeling in asthma?
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Study Notes
Asthma Overview
- Asthma is a chronic inflammatory airway disorder causing recurrent bronchospasm.
- Symptoms include wheezing, breathlessness, chest tightness, and cough, especially at night or early morning.
- Key characteristics include intermittent and reversible airway obstruction.
- Chronic inflammation with eosinophils and hyperreactivity of bronchial smooth muscle cells are also present.
- Increased mucus secretion is another key feature.
Severe Airway Hyperreactivity
- In severe cases, even trivial stimuli can trigger attacks.
- Diverse cells play a role in the inflammatory response, notably eosinophils, mast cells, macrophages, lymphocytes, neutrophils, and epithelial cells.
Asthma Incidence
- Asthma prevalence has significantly increased in affluent countries over the past few decades.
- One hypothesis for this trend is the hygiene hypothesis, proposing a lack of exposure to microbes and allergens in early childhood leads to immune system hyperreactivity later in life.
- However, no mechanistic evidence supports this hypothesis.
Asthma Pathogenesis
- Genetic predisposition to type I hypersensitivity (atopy) contributes.
- Chronic and acute inflammation of the airways plays a key role, including differing patterns (eosinophilic, neutrophilic, etc.).
- Bronchial hyperresponsiveness to various stimuli (e.g., respiratory infections, environmental factors, allergens) is crucial.
- Asthma can be classified as atopic (allergy-related) or nonatopic.
Atopic Asthma
- The most common form of asthma, typically starting in childhood.
- Often associated with a positive family history of atopy (allergy) or asthma.
- Allergens like dust, pollen, animal dander, or food, or infections can trigger attacks.
- Diagnosis relies on episodic symptoms and airflow improvement with bronchodilators; skin testing for allergens and immunoassays for IgE antibodies.
Type 2 Helper T Cells (Th2)
- Activated Th2 cells release cytokines (e.g., IL-4, IL-5, IL-13) triggering a cascade of events:
- Increased IgE production from B cells, sensitizing mast cells to allergens.
- Increased eosinophil recruitment and activation leading to mucus production.
- The process involves IgE binding to Fc receptors on mast cells resulting in inflammatory mediator release.
Early and Late Phase Reactions
- Early phase: characterized by bronchoconstriction, increased mucus and vasodilation, caused by mediators like histamine and leukotrienes.
- Late phase: inflammatory response involving Th2 cells, eosinophils and other leukocytes.
- Both phases lead to structural changes known as airway remodeling
Airway Remodeling
- Long-term inflammation can cause changes in airway structure including smooth muscle hypertrophy, mucus gland increase, vascular changes, and subepithelial fibrosis.
Nonatopic Asthma
- Patients usually lack evidence of allergen sensitization.
- Respiratory infections (e.g., viruses) and environmental triggers (e.g., air pollutants, cold air) are more common triggers.
- Similar symptoms and treatment options to atopic asthma, though less common.
Drug-Induced Asthma
- Aspirin is the most common trigger.
- A complex mechanism involving prostaglandin abnormalities is likely.
- Occupational exposure (e.g. epoxy resin, organic/chemical dusts) can trigger similar reactions.
Asthma Morphology
- Lungs are inflated.
- Thick, tenacious mucous plugs ("Curschmann spirals"), eosinophils, and crystals ("Charcot-Leyden crystals") are common findings.
- Airway thickening, increased vascularity, and mucus gland enlargment are characteristic.
Asthma Clinical Features
- Severe dyspnea (shortness of breath) and wheezing are key symptoms due to bronchoconstriction and mucus plugging.
- Episodes typically last for hours to days.
- Patient intervals between attacks may be symptom-free but show subtle impairments on pulmonary function testing.
Asthma Treatment
- Mild episodic asthma: primarily treated symptomatically with bronchodilators (e.g., beta-agonists), and glucocorticoids, sometimes with leukotriene inhibitors.
- Severe cases: Treatments may include anti-IgE therapy (blocks IgE action) or therapies targeting IL-4, IL-5, and IgE, as well as other specific immune mediators.
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Description
Explore the fundamental aspects of asthma, a chronic inflammatory airway disorder. This quiz covers its symptoms, mechanisms of airway hyperreactivity, and the trends in asthma incidence, especially in affluent countries. Test your knowledge on this significant health issue and its underlying characteristics.
