Bodily Defenses Image Map

Smoking

Overview
Smoking is the leading cause of lung cancer, which causes more deaths than any other form of cancer.  Smoking affects both smokers and people nearby, through second-hand smoke.

Why is smoking hazardous?

There are three major reasons smoking is dangerous:

1. "The nicotine effect"

  • Nicotine is one of the major chemical components in the tobacco leaves used to make cigarettes.  Nicotine reaches the brain just a few seconds after smoking begins.  The rich blood supply in the lungs picks up any chemical in the air very rapidly.
  • Nicotine causes the nervous system to stimulate the release of adrenaline into the blood.  When adrenaline increases in the blood, it causes the heart to beat faster, the blood vessels to constrict (to become more narrow), and the breathing rate to increase.  Nicotine constricts blood vessels directly too.  Constricted vessels create a large resistance for the heart to pump against.  Nicotine also constricts the blood vessels in the heart and can promote heart attacks. 
  • Initially nicotine gives the brain a boost, but when the effect wears off, fatigue and depression set in.
  • Nicotine is one of the most addictive drugs known.  Just a few puffs can create cravings for nicotine in some people. And young people are more likely to get addicted quickly than older people!

2.  Lung irritation

In addition to nicotine, the burning of tobacco produces other hazardous materials. Some of them are:  

Acetone - a solvent, used in nail polish remover, for example.

Carbon Monoxide - an odorless, colorless poisonous gas that is lethal in large doses. In smaller doses, carbon monoxide causes increased heart rate and shortness of breath. Carbon monoxide attaches itself to the red blood cells and blocks their ability to carry oxygen.

Formaldehyde - a preservative for dead bodies. In cigarette smoke, this chemical is a known carcinogen and causes respiratory problems.

Hydrogen Cyanide - short-term exposure can lead to headaches, dizziness, nausea and vomiting.

Lead - a highly toxic metal, capable of causing serious damage to the brain, kidneys, nervous system and red blood cells.

Cigarette smoke contains many organic tars that irritate delicate lung tissue.  As the irritation increases, the lung linings begin to break down, reducing the efficiency of the lungs.  One common disease resulting from the break down of the lung linings is emphysema.  

  • In emphysema, the alveoli over inflate because they are trying to let more oxygen into the blood.  This over inflation reduces the elasticity of the alveoli and makes them less efficient.  
  • As emphysema progresses the lungs become less elastic and can no longer clear the air out of the lungs.  
  • When the air remains in the lungs for a longer period of time than normal, the oxygen is depleted and carbon dioxide builds up.  
  • When carbon dioxide builds up in the lungs, the alveoli swell and may even burst open.  This causes tissue damage and can lead to scar tissue.
  • The lungs do not exchange old air for new air efficiently.

3.  Lung cancer-  Smoking is the leading cause of lung cancer in the United States.  Lung cancer causes more deaths in the United States than any other type of cancer.  For more info click here.  We will discuss this in depth on the next page.

Similar problems occur with snuff and chewing tobacco. The nicotine effect is the same. The irritation and cancer effects can be the same, except it is the mouth that is affected instead of the lungs.

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