1. DRUGS
TYPES OF DRUGS
A drug is a chemical substance that can alter the way in which a part of the body works.
A medicine is a chemical treatment for an illness or disorder.
Antibiotics are drugs which are medicines. All medicines contain drugs. Antibiotics kill bacteria, but do not harm other
living cells. Most of them are made by fungi. They kill bacteria by stopping them making their cell walls.
There are many drugs, affecting different parts of the body. Some drugs act directly on the nervous system. These are
grouped according to the effect they have:
- Stimulants speed up the action of the nervous system. They usually make the drug user feel more confident and alert,
and include amphetamines, caffeine and nicotine.
- Depressants slow down the action of some part of the nervous system. The user feels sleepy and less anxious, but may
become dependent on the drug. Examples: barbiturates, alcohol and cannabis.
- Narcotics act like depressants but particularly target the brain. They work as pain-killers and may bring about a feeling
of drowsy well-being or euphoria. Narcotics such as heroin are very likely to bring about drug dependence in the user.
- Analgesics are mild pain-killers. Aspirin and paracetamol are widely used analgesics.
- Addictive drug: is one which causes a person to become dependent on it- they are not able to stop taking it without
suffering severe psychological and physical symptoms. Heroin is an addictive depressant. A person becomes physical
addicted to a drug when the drug is necessary for the normal working of the body. If the person cannot get the drug, then
he or she will get withdrawal symptoms. Someone suffering withdrawal symptoms from heroin, for example, may
vomit, tremble, sweat profusely and have severe abdominal pain after a little as four hours without the drug. Heroin users
may find they eventually need to inject the drug directly into the blood system in order to obtain the effect they crave.
This can lead to using non- sterile needles, which- if they have previously been used by someone else- may carry the
AID´S virus.
ALCOHOL
- Alcohol is a powerful depressant. It lengthens reaction time, which means that lengthens the time you take to respond to
a stimulus.
- Alcohol can increase aggression in some people. Different people react differently to alcohol. In some people, it releases
their inhibitions so they are more likely to be violent or commit other crimes.
- Large intakes of alcohol can kill. People can die as a direct result of drinking a lot of alcohol over a short period of time.
Alcohol is a poison. Large intakes can result in unconsciousness, coma and even death.
- Alcoholism is a dangerous disease. The liver is often damaged because it breaks down drugs such as alcohol. One form
of liver disease resulting from alcohol is cirrhosis, where fibres grow in the liver. This can be fatal. Excessive alcohol
drinking also damages the brain. Over a long period of time, it can cause loss of memory and confusion. One way in
which the damage is done is that alcohol in the body fluids draws water out of the cells by osmosis. When this happens to
brain cells, they shrink, and may be irreversibly damaged. This osmotic effect is made worse because alcohol inhibits the
release of a hormone which stops the kidneys from allowing too much water to leave the body in urine (ADH). So
drinking alcohol causes a lot of dilute urine to be produced, resulting in low levels of water in blood.

2. CIGARETTE SMOKING
Tobacco smoke contains irritants and carcinogens:
COMPONENT EFFECT ON THE BODY
NICOTINE
-It is addictive
-It affects cells in the brain. It is a stimulant
-It makes blood vessels get narrower. This can increase
blood pressure and increase the risk of a heart attack or
stroke.
TAR
- It is carcinogenic- that is, it can cause cancer. It damages
cells´ ability to regulate their division , so cells may divide
uncontrollably and produce a lamp of cells called a tumour.
CARBON MONOXIDE
It combines with haemoglobin in the blood. This means that
the haemoglobin is not available to transport oxygen. The
person may not be able to get enough oxygen to their
muscles to allow them to do exercise.
PARTICULATES - They may get trapped inside the lungs, where they can
cause irritation.
- The white cells may try to destroy them, but may destroy
the cells around the alveoli instead.
- This may cause the walls of the alveoli to break down,
resulting in emphysema.
Several of the chemicals in cigarettes smoke can harm the cells lining of the respiratory passages.
-Normal airways: Cilia of ciliated cells beat and sweep mucus up to the mouth.
- Airways of a smoker:
- There are fewer cilia and those that remain work less well. Goblet cells (production of mucus) work faster than usual,
producing extra mucus. Mucus trickles down to the lungs and stays there. Mucus also provides a good place for bacteria
to live, causing inflammation in the lung and bronchi, bronchitis.
Passive smoking is breathing in someone else´s cigarette smoke. This smoke contains tar and other carcinogens, so long-
term exposure to it increases the risk of developing lung cancer.