13. The Use and Abuse of Drugs


1 . Drug:

  • Any externally administered substance that modifies or affects chemical reactions in the body

2 . Drugs can be grouped as follows:

  • I. Sedatives (Depressants):
  • Slow down the brain and make you feel sleepy;
  • Include tranquilizers and sleeping pills;
  • e.g. alcohol


  • II. Stimulants:
  • Speed up the action of the brain and make you feel alert;
  • Sometimes given to people who are suffering from severe depression;
  • e.g. coffee, tea and nicotine


  • III. Hallucinogens:
  • Cause a person to experience illusion, hallucinations and distorted images;
  • e.g. cannabis


  • IV. Opiates:
  • Include opium, morphine and heroin;
  • Relieve pain and induce sleep and stupor


3 . Drugs may cause:

  • I. Tolerance:
  • If taken over a long period of time, the dosage has to keep increasing in order to have the same effect;
  • If the dosage continues to increase, it will become so large that it may cause death;
  • e.g. people who drink alcohol in order to relieve anxiety may have to keep drinking more and more before they feel relaxed


  • II. Dependence:
  • It is the condition in which the user cannot do without the substance;
  • e.g. cigarette smoking can cause emotional dependence – crave for it, may be bad tempered, anxious or depressed without it;
  • May also cause physical dependence (addiction)  and cause withdrawal symptoms(??)



13.1 Antibiotics
1 . Antibiotics:

  • Chemicals that are widely used to treat many infectious diseases caused by microorganisms;
  • Produced by certain bacteria and moulds and some are man-made;
  • Do not harm viruses

2 . Four main types of anti biotics:

  • I) Penicillins:
  • Made by the fungus Penicillium;
  • Attack a few bacteria (Narrow-spectrum antibiotics)


  • II) Cephalosporins:
  • Made by the mould Cephalosporium;
  • Useful against penicillin-resistant bacteria


  • III) Tetracyclines:
  • Made by the bacterium Streptomyces aurofaciens;
  • Act against a variety of bacteria (Broad-spectrum antibiotics)


  • IV) Erythromycins:
  • Work against the same type of bacteria as penicillin;
  • Useful against penicillin-resistant bacteria


3 . Anaesthatics:

  • Drugs that made the body unable to feel pain;
  • e.g. Cocaine, which causes a loss of sensation in the area where it is injected

4 . Analgesics:

  • Drugs that can relieve pain without causing numbness or affecting consciousness;
  • e.g. Aspirin, which relieves minor pain and reduces fever,
  • If taken in large doses, may produce some side effects, e.g. gastric ulcers


13.2    Effects of heroin

1 . Heroin:

  • Obtained from opium;
  • A type of painkillers;
  • Used as a sedative and powerful analgesic;
  • Highly addictive (drug dependence), often abused by drug users


2 . Effects of heroin:

  • Social problems;
  • Brain damage (affect the brain);
  • Lung damage (affect the lungs);
  • Affect the diet – lose of weight, constipation, lose of appetite, gastric ulcers
  • Withdrawal symptoms:
  • Physically ill (experiences nausea, vomiting, uncontrolled trembling);
  • Mentally disturbed (experience acute anxiety, depression, etc.).


13.3 Effects of alcohol

1 . Alcohol:

  • A depressant;

2 . Effects of alcohol:

  • Slow down some brain functions;
  • Reduce nervous tension and worries;
  • Self-control is reduced;
  • Blurred vision and poor muscular co-ordination;
  • Anaesthetize the brain and can cause unconsciousness;
  • Addiction (drug dependence).
  • Damage the liver because alcohol is broken down in the liver;
  • Social problems


13.4 Effects of tobacco smoke
1 . 3 major components of tobacco smoke:

  • Nicotine – addictive drug;
  • Tar -a brown, sticky substance that accumulates in the lungs during smoking;
  • Carbon monoxide (CO).

2 . Effects of nicotine:

  • Stimulates the brain making the smoker alert and relaxes the muscles then, dulls the brain and senses;
  • Release adrenaline -increase the rate of heartbeat and blood pressure;
  • Clots the blood easily -increasing the risk of blood clots blocking the blood vessels -clotting of the coronary arteries cause heart attack, clotting of the capillaries of the brain cause stroke;

3 . Effects of carbon monoxide:

  • Reduces the efficiency of the red blood cells to transport oxygen – may cause death;
  • Increases the rate of the deposition of fatty substances on the inner walls of arteries, causing lumen to become narrower;
  • Damages the lining of blood vessels -increasing the tendency of the blood to clot and so block the blood vessels;
  • It is more readily to combine with haemoglobin to form carboxyhaemoglobin instead of oxyhaemoglobin.

4 . Effects of tar:

  • Contains cancer-causing (carcinogens) chemicals;
  • Uncontrolled multiplication of cells results in outgrowths or lumps of tissue (cancer) -blocking off the air sacs, reducing the efficiency for gaseous exchange;
  • Paralyses the cilia from removing dust particles from the lungs and trachea.

5 . Smoking-related diseases:

  • Lung cancer;
  • Chronic brochitis;
  • Emphysema

6 . Effects of smoking during pregnancy:

  • Brain development of the fetus is affected -the child may have learning difficulties in later life;
  • The fetus grows more slowly, born smaller, more fragile and may die quickly within the first few days of life;
  • A higher risk of the baby being born prematurely;
  • The baby has a greater risk of being born dead (stillborn).

7 . Nowadays,many people regard smoking as no longer socially acceptable.


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