Q.Explain three respiratory disorders in man. OR Name the two heart sounds. How are they produced?

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.

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.

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). …