Smoking
Smoking is one of the most important modifiable risk factors that cause several pathologies of the gaseous exchange system.

Components Of Cigarette Smoke

Cigarette smoke contains different components that damage the airway. This includes:

1. Tar: A mixture of chemicals that causes cancer.
2. Nicotine: it is the addictive component of the cigarette. It acts on nerve cells in the brain and other parts of the body. This causes the release of dopamine that gives a pleasant sensation and adrenaline which is associated with increased heart rate and breath rate.
3. CO: it binds with hemoglobin and forms a compound called carbaminohemoglobin. This reduces the oxygen-carrying capacity of the blood.

Disorders Of Airway:

Cigarette smoke leads to several airway disorders. Some of the major disorders are:

COPD:

This includes several disorders that are characterized by airflow limitation and difficulty in breathing.

Chronic Bronchitis


Definition:

Productive cough with sputum persistent for 3 months for at least 2 consecutive years.

Pathology:

Cigarette smoke causes hyperplasia of goblet cells leading to overproduction of mucus. This leads to the plugging of mucus in the airway. Later the mucus plugging leads to bacterial invasion causing bronchitis.

Symptoms:

Following are the symptoms of chronic bronchitis:

1. Persistent Cough
2. Sputum
3. Wheezing
4. Chest tightness

Emphysema:


Definition:

Disorder in which airspaces in the lungs are damaged.

Pathology:

Smoking leads to inflammation in the lungs causes release of chemicals called elastase. These chemicals digest elastic fibers in the alveoli. Thus, makes the alveoli less elastic. Due to which they get burst. This decreases the surface area for diffusion.

Lung cancer:

Cigarette smoke contains various irritants that destroy the ciliated lining of the airway. This results in a change of ciliated epithelium to the nonciliated epithelium. This change of one cell type to another is called metaplasia. This serves as the basis of cancer.

Symptoms:


1. Chest pain
2. Fatigue
3. Weight loss
4. Breathlessness

Effect Of Cigarette Smoke On Cardiovascular Symptom:

Cigarette smoke increases the risk factor for the development of atheromatous plaques in the arteries. This is called atherosclerosis.

Atherosclerosis

Atherosclerosis is a disorder that is associated with the development of atheromatous plaques in the arteries and thickening of the vessel. These plaques consist of lipids and fibers. This reduces the diameter of arteries thus increasing the blood pressure of an individual.

An increase in the size of plaques leads to thrombus formation. These thrombi often get dislodge from the artery and form emboli. These emboli being smaller in size ofter get carried by the blood and obstruct the smaller capillaries.

The obstruction of capillaries cut off the blood supply to the organ. When the organ is brain it results in a stroke.

The hardening of arteries causes it less elastic thus on increasing pressure the vessel gets ruptures. 

This is another cause of stroke.

When these emboli obstruct the vessel carrying blood to heart they give rise to coronary artery disease. The supply to the heart muscles is stopped leading to the death of cardiac muscle giving rise to Myocardial Infarction. (heart attack)

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