Smoking can cause lung disease, heart disease and certain cancers.
Nicotine is the addictive substance in tobacco. It quickly reaches the brain and creates a dependency so that smokers become addicted.
Effects on the air passages
Sticky mucus in the lungs traps pathogenMicroorganism that causes disease.. The mucus is normally swept out of the lungs by the ciliaTiny hair-like projections from a cell that usually allow it to move a substance past the cell (for example, in the bronchioles in the lungs). on the epithelial cellA cell that forms part of an epithelium. lining the trachea, bronchiThe plural of 'bronchus'. The bronchi are the two major air tubes in the lungs. and bronchiolesThe many small, branching tubules into which the bronchi subdivide.. However, cigarette smoke contains harmful chemicals that paralyse these cilia, leading to a build-up of mucus and a smoker’s cough. Smoke irritates the bronchi, causing bronchitis.
Effects on the alveoli
Smoke damages the walls of the alveoliTiny air sacs in the lungs, where gas is exchanged during breathing.. The alveoli walls break down and join together, forming larger air spaces than normal. This reduces the ability of the blood to carry oxygen, putting a strain on the heart which increases the risk of developing coronary heart disease or strokes.
Carbon monoxide
Carbon monoxide, CO, combines with the haemoglobinThe red protein found in red blood cells that transports oxygen round the body. in red blood cells. This reduces the ability of the blood to carry oxygen, putting a strain on the heart, which increases the risk of developing coronary heart disease or strokes.
Lung cancer
Tobacco smoke contains many carcinogenA chemical or other agent that causes cancer., including tar. Smoking increases the risk of lung cancer, and cancer of the mouth, throat and oesophagus.