Asthma - B. Pharma 2nd Semester Pathophysiology notes pdf







At the end of this PDF Notes, student will be able to

        Define Bronchial asthma

       Explain the pathophysiology of Bronchial asthma

       Describe the symptoms of Bronchial asthma


       Disorder of the respiratory system that leads to episodic difficulty in breathing

       Chronic inflammatory disorder of the airways in which many cells and cellular elements play a role

       Mast Cells, Eosinophils, T Lymphocytes, Macrophages, Neutrophils , Epithelial Cells

Bronchial  Asthma

ü  Also called reversible airway obstruction

ü  Clinical syndrome characterized by recurrent bouts of bronchospasm   

ü  Increased responsiveness of the tracheobronchial smooth muscles to various stimuli

ü  Results in narrowing of the airway

ü  Chronic inflammatory disorder with reversible airflow obstruction

ü  Inflammation of bronchial wall mediated by eosinophils, mast cells & lymphocytes

ü  Hyper-responsiveness of bronchi – narrow readily with stimuli

ü  In late stages – irreversible

Etiology of Asthma

Extrinsic or allergic

ü  History of `atopy` in childhood

ü  Family history of allergies

ü  Positive skin test

ü  Raised IgE level

ü  Below 30 years of age

ü  Less prone to status asthmaticus

Intrinsic or idiosyncratic

ü  No family history of allergy

ü  Negative skin test

ü  No rise in IgE level

ü  Middle age onset

ü  Prone to status asthmaticus



     Aspirin, ibuprofen and other prostaglandin synthetase inhibitors, beta blockers


     Nuts, fish, sea food, dairy products, food colouring

Other industrial chemicals

     Wood or grain dust, cotton dust, cigarette etc


     Cold, exercise, hyperventilation ,viral respiratory tract infections, emotion or stress

Pathophysiology of Asthma

Main features of asthma:             

      Hypertrophy of bronchial smooth muscle

      Hyperplasia of epithelial cells

      Mucus gland hypertrophy

      Airway oedema

      Acute bronchoconstriction

      Impaired mucociliary clearance

       Early exposure to

            - Allergens

            - Viral infections

            - Diet induced

       Early onset: Atopic

           -Positive family history

           -Readily form IgE to common allergens react with mast       cells on surface & activate IgE – histamine release

           -Many more mediators

v  Changes in the airway

ü  Epithelial shedding

ü  Airway hyper-responsiveness

ü  Microvascular leakage – exudate mucus plugging

ü  Neuronal imbalance – bronchoconstriction

v  IgE-antibody-mediated reaction on the surface of the mast cell leads to release of mast cell components

v  Histamine - triggers rapid bronchoconstriction

v  Eosinophils release LTC4 and PAF

v  Epithelial damage and thick viscous mucus produced causing deterioration in lung function

v  Epithelial damage

v  Increases access of various irritants to the cholinergic receptors,

v  Bronchoconstriction mediated by the parasympathetic nervous system

Signs and Symptoms
 of Asthma

       Persistent cough

       Dyspnoea - difficulty in breathing

       Wheezing - a high pitched noise due to turbulent airflow through a narrowed airway

       Tightness of chest

       Shortness of breath

       During attacks - fatigue, cyanosed, lethargic, confused, breathless, rapid breathing (> 30 breaths/minute)

Clinical Features of Asthma

       Episodic or chronic

       Triad of:

        - Dyspnea (difficulty in breathing)

        - Wheezing (additional sounds)

        - Cough (persistent)

       Productive sputum



           Pulsus paradoxus


           Cyanosis, bradycardia in severe cases

           Silent chest


       Chronic inflammatory disorder with reversible airflow obstruction

       Inflammation of bronchial wall mediated by eosinophils, mast cells & lymphocytes

       IgE-antibody-mediated reaction

       Release of mast cell components which  triggers rapid bronchoconstriction

       Persistent cough, recurrent episodes of difficulty in breathing associates with wheezing, chest tightness, shortness of breath, abnormal lung function are the common symptoms

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