When you smoke a cigarette, the smoke enters the mouth and nose, travelling down the throat into the lungs. Smoke enters the lungs and starts to damage the cilia in the lining of the lungs. The smoke and toxins eventually cause the cilia to die.
The lack of oxygen and increase in tar causes breathlessness, wheezing, dizziness and tiredness. Carbon monoxide in the blood stream stops the blood carrying oxygen around the body.
Although most smoke enters the lungs, some is swallowed. It travels down the oesophagus into the stomach. Chemicals from the smoke enter your blood stream and travel around the body. This can cause cancer in other parts of the body e.g. pancreas, cervix or liver.
Smoke will eventually become part of urine, which passes through the bladder, which can cause kidney and bladder cancer.