Tobacco smoke containes a number of harmful ingredients such as carbon monoxide, heavy metals, tars and nicotine. Each of these is toxic by itself when inhaled.
The immediate effect from tobacco smoke is the "buzz" associated with nicotine. When ingested, nicotine causes a rapid heart beat, rapid breathing and a feeling of light headdedness. Nicotine is highly addictive, and after a few cigarettes or pouches, one starts "nicking" or feeling cranky and irritable if the nicotine craving is not satisfied.
There are carcinoginic chemicals in cigarette smoke that bind with protiens in DNA causing genetic mutations and birth defects.
In the body, carcinogens from tobacco smoke can bind to blood proteins and to DNA, and can thus produce gene mutations and chromosomal abnormalities. Smoking can also cause changes in the metabolism of cells or tissues, resulting in changes to the way foreign substances are broken down by the body. (http://www.greenfacts.org/en/tobacco/)
Diseases associated with tobacco use are myriad ranging from the most common heart disease and lung cancer to thyroid disease and bladder cancer. Please check out the links below for more detailed information.
At your age, smoking cigarettes can be more addictive than an adult. So addiction is a number one concern. An addict will smoke more frequently and therefore endanger his body with more of the negative side effects. A smoker introduces numerous carcinogens into the body which can lead to cancer. Lung cancer is the number one type of cancer due to the close proximity of smoke in the lungs. But other cancers may develop too. All aspects of the respiratory system are affected at once. Linings in the sinus, and lung tissue are easily damaged as cilia, or hairlike projections that sweep away foreign objects are destroyed. Inside the lung, the small sacs called aveoli are damagedand this could affect the exchange of oxygen and carbon dioxide. A disease called emphysema is common among smokers as many alveoli are damaged. There are a higher incidences of colds, flu, and respiratory infections because immunity is weakened. Best not to start or quit immediately before permanent damage is done. Quitting smoking or never starting is the number one preventative habit to extend one's life or prevent early death!
It has been suggested that smoking affects our vision. There has been so much literature examining the effects of smoking on our visual perception: color, contrast sensitivity, dark adaptation,.......
More research has been taking place on how smoking can have an impact on glaucoma. So far there are inconclusive evidence suggesting any relationship. It's a debate of whether it's nicotine or smoking. Cigarettes contain 4000 chemicals and it is though that nicotine can have color disturbances on smokers. Some changes in dark adaptation has also been seen in smokers.