Q.Cigarette smoking causes emphysema. Give reason.
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Respiratory Disorders: When the Airway Fails
Think of your respiratory system as a tree. The trunk is your trachea, the branches are your bronchi and bronchioles, and the leaves are the alveoli — tiny air sacs where oxygen actually enters your blood. Every breath you take is a delivery system: fresh air in, waste air out. A respiratory disorder is anything that breaks this system at any point — the pipe gets narrow, the walls get damaged, or the sacs get clogged.
The intuition is simple: if the airway is blocked, you can't get enough oxygen. If the alveoli are destroyed, oxygen can't cross into the blood. If the lung tissue is scarred, it can't expand properly. Each disorder attacks a different part of this machinery.
Asthma — The Reversible Narrowing
Asthma is a chronic inflammatory condition of the airways. The bronchi and bronchioles become hypersensitive to triggers — dust, pollen, cold air, exercise, or even stress. When triggered, three things happen at once:
- The smooth muscle around the airways contracts (bronchospasm)
- The lining swells (inflammation)
- Mucus clogs the passage
The result: the airway diameter shrinks dramatically. Breathing out becomes harder than breathing in, because the narrowed tubes collapse further during exhalation. You hear a characteristic wheeze — the sound of air being forced through a tight pipe.
Asthma is reversible. Between attacks, lung function can be nearly normal. Treatment uses bronchodilators (to relax muscle) and corticosteroids (to reduce inflammation).
Emphysema — The Destroyed Alveoli
Emphysema is a destructive disorder, almost always caused by long-term smoking. The walls between alveoli break down, turning many small sacs into fewer, larger, useless sacs.
Why is that bad? Gas exchange depends on surface area. A healthy lung has about 300 million alveoli with a total surface area the size of a tennis court. In emphysema, that surface area collapses. The lungs also lose their elastic recoil — they stretch but can't snap back, so air gets trapped inside. The patient develops a barrel-shaped chest and struggles to exhale fully.
Emphysema is irreversible. Destroyed alveoli do not regenerate. The damage is permanent.
Occupational Lung Disorders — The Dust Diseases
These are caused by inhaling specific mineral or organic dusts over years. The body's immune response to these particles leads to fibrosis — scarring of lung tissue. Scarred tissue is stiff; it cannot expand or contract properly.
Silicosis — caused by inhaling silica dust (from mining, stone cutting, sandblasting). Silica particles are sharp and insoluble. Macrophages (immune cells) try to engulf them but die in the process, releasing enzymes that trigger scarring. The lungs become progressively stiff and non-functional.
Asbestosis — caused by inhaling asbestos fibers (from insulation, construction). These fibers are long and needle-like. They lodge in the alveoli and cause chronic inflammation and fibrosis. Asbestos exposure also dramatically increases the risk of lung cancer and mesothelioma (a cancer of the lung lining). …
Cigarette smoking causes emphysema because it is named as a major cause of the damage to the alveolar walls that defines this chronic disorder. Since the alveolar walls form the gas-exchange surface, this smoking-induced damage decreases the respiratory surface available for oxygen and carbon-dioxide exchange, producing the progressive breathing di …
Cigarette smoke damages the walls of the alveoli, and since this is exactly what defines emphysema, sustained smoking directly causes and worsens the disorder.
Emphysema is a chronic disorder in which the walls of the alveoli are damaged, and because these walls form the surface across which gases are exchanged between air and blood, this damage decreases the respiratory surface available for exchange. …
Method: Explaining a cause-and-effect disease mechanism
This method applies to any "give reason" question that asks you to connect a trigger (like a habit or exposure) to a named disease.
Steps
Step 1: Identify what the disease actually damages, structurally
Before connecting cause to disease, pin down the specific structure the disease is defined by damaging. Emphysema, by definition, is damage to the walls of the alveoli — not the airway, not the lung tissue generally, but specifically the alveolar walls.
Step 2: Connect the structural damage to a functional consequence
Ask: what job does the damaged structure do, and what happens when it's lost? The alveolar walls form the gas-exchange surface, so damaging them directly shrinks the total respiratory surface area available for oxygen and carbon dioxide to cross.
Step 3: Link the named trigger to the damage mechanism …
- CBSE 2024Set HALF_YEARLY1 markQ.State whether True or False: Asthma, pneumonia, tuberculosis etc. are the main respiratory diseases.
›Reveal solutionSolution
This statement is True: asthma, pneumonia and tuberculosis are all well-recognised respiratory disorders that impair normal breathing and gas exchange.
Asthma is a condition in which the bronchi and bronchioles become inflamed and constrict, causing difficulty in breathing, wheezing and shortness of breath, often triggered by allergens or irritants. Pneumonia is an infection (commonly bacterial, e.g. Streptococcus pneumoniae) that inflames the alveoli of one or both lungs, which then fill with fluid or pus, severely reducing the surface area available for gas exchange and causing fever, cough and breathing difficulty. Tuberculosis (TB) is a chronic bacterial infection caused by Mycobacterium tuberculosis that primari …
- CBSE 2021Set ANN1 markQ.Respiratory disorder in which alveolar walls are damaged, due to which respiratory surface is decreased.
›Reveal solutionSolution
Emphysema is the chronic disorder in which alveolar walls are damaged/destroyed, reducing the total respiratory surface area available for gas exchange.
In emphysema, prolonged exposure to irritants -- most commonly cigarette smoke -- destroys the elastic tissue and thin walls of the alveoli. Adjacent alveoli fuse together into larger, fewer air sacs. This dramatically decreases the total surface area available fo …
- CBSE 2020Set ANNUAL1 markQ.Name one respiratory disorder in man.
›Reveal solutionSolution
Asthma — difficulty in breathing caused by inflammation and narrowing of the bronchi/bronchioles, often triggered by allergens — is a well-known human respiratory disorder.
Several disorders can affect human breathing and gas exchange:
- Asthma: difficulty in breathing causing wheezing due to inflammation of bronchi and bronchioles, often triggered by allergens, dust, or pollutants. …
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