UK GCSE level age ~14-16, ~US grades 9-10 Biology revision notes re-edit 17/05/2023 [SEARCH]

 Non-communicable diseases: 6. Different types of drugs, problems with illegal drugs - lifestyle choices

Doc Brown's biology exam revision study notes

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There are various sections to work through, after 1 they can be read and studied in any order.

INDEX of notes on non-communicable diseases

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(6) Different types of drugs, problems with illegal drugs - lifestyle choices

  • Realise that many drugs are useful and relatively harmless and fulfill their medical function, BUT, some drugs are chemical substance that have narcotic or hallucinogenic effects on the central nervous system, causing changes in psychological behaviour and possible addiction, despite their usefulness.

    • Drugs are dangerous if misused, which is why some drugs cannot be bought of the counter of a shop (e.g. local chemist) without a medical prescription from you doctor, but other drugs, like the painkiller paracetamol, can readily bought without prescription from your GP.

    • It can sometimes be difficult to state whether the addiction is a physical or mental dependence.

    • If some drugs are over used, you may become addicted to them, which means you have a physical craving for more of it, without which you can suffer withdrawal symptoms - extreme craving is symptomatic in itself of addition, and sometimes the body reacts physically in a negative way e.g. becoming very irritable, shaky hands.

    • Tolerance is another problem that arises when the body becomes used to a drug and progressively needs larger quantities of the drug to give the same effect. The increasingly higher dose rate can lead directly to addiction and examples range from legal drugs like alcohol and nicotine in tobacco and illegal use of cocaine and heroin.

    • Addiction can be cured by slowly decreasing the amounts of the drug administered, but most drug addicts required lots of support from e.g. the NHS in the UK, help groups and rehabilitation centres (politely referred to in pop songs as 'rehab').

  • Be able to describe the general effects of some drugs:

    • a) Painkillers that block pain nerve impulses, including morphine - yes it is a narcotic, but widely prescribed safely and legally!

      • Painkillers like aspirin, paracetamol and ibuprofen reduce pain and inflammation throughout the body, but can used on specific locations e.g. a dentist might use a local anaesthetic to extract a tooth.

        • These are usually safe, with no side-effects, but excess aspirin can cause damage to the lining of the stomach.

      • If the nerve impulses to the brain are blocked, we do not experience a pain sensation and morphine molecules are very effective at doing this.

        • Morphine type drugs are amongst the strongest painkillers we use.

      • Different painkillers are more effective in particular situations and there maybe safer alternatives that are not as dangerous or addictive e.g.

        • paracetamol, an analgesic, is a good relatively safe painkiller for headaches.

        • Ibuprofen is a good anti-inflammatory drug for muscle pain and rheumatoid arthritis.

      • Heroin and morphine were developed as painkillers, but both are illegal drugs and highly addictive drugs that have wrecked many lives.

    • b) Hallucinogens that distort sense perception, including illegal LSD and ecstasy.

      • When taken, hallucinogens create hallucinations in your mind so you experience distorted sounds and images because the normal processing of nerve impulse is interfered with.

      • They can give you feelings of boundless energy, but also cause dehydration and possible death.

    • c) Stimulants that increase the speed of reactions and neurotransmission at the synapse, including caffeine.

      • Stimulants increase the activity of the brain by increasing the amount of neurotransmitters at certain neurone synapses in the central nervous system i.e. they speed up your brain functions.

      • Stimulants increase your speed of reaction i.e. decrease your response time to a given physical or mental stimulus.

      • Many people take coffee to make them more alert and 'fully awake' in the morning because coffee is a rich source of the stimulant caffeine.

      • Amphetamine (speed) and methedrine are illegal stimulants and give you the feeling of having great energy. Unfortunately, users become psychologically dependent  on such drugs and develop the feeling of always needing them leading to deterioration of mental health and character.

    • d) Depressants that slow down the activity of the brain (opposite of stimulants), including alcohol.

      • These include alcohol, cannabis and heroin which make you feel relaxed and drowsy.

      • Barbiturates are legal prescription depressants and slow down the nervous system. They can reduce feelings of anxiety and help you sleep, BUT, they slow down your reaction times and become habit forming - another case of dependency addiction and create feelings of aggression and paranoia.

      • Depressants slow down your responses and so increase your reaction times to a physical or mental situation i.e. they slow down your brain functions.

      • 'Drink driving' is considered a dangerous activity and a serious criminal offence because a drunk (or not so drunk) driver is a danger to others and the driver himself/herself on the road.

      • There is a legal limit of alcohol in your blood which you must be below to 'legally drive' a car, and its pretty low!

      • Revise any experiments-investigations you did on reaction times e.g. the falling ruler experiment.

    • e) Recreational drugs maybe legal or illegal.

      • These substances are taken for non-medical reasons.

      • Substances such as caffeine, tobacco and alcohol are legal, but not necessarily harmless!

      • Illegal recreational drugs include cannabis, ecstasy, cocaine and heroin, all of which have dangerous side-effects.

    • f) Hormones are used to improve sporting performance e.g. testosterone and anabolic steroids.

      • These can have multiple effects e.g. testosterone acts as stimulant to increase physical activity.

      • Anabolic steroids increase muscle mass.

      • BUT, they may be illegal.

  • Be able to explain the effects of some chemicals in inhaled cigarette smoke resulting from tobacco combustion, including:

    • Nicotine as an addictive drug which smokers can become dependant on and the more you smoke, the more you may become dependent on it - like it or not, smoking can become a drug addiction.

      • Nicotine speeds up heart rate and raises blood pressure increasing the risk of heart disease, heart attacks and strokes.

      • BUT there are other serious risk factors, (a) to (c), associated with smoking

      • (a) Tar as a carcinogen - several molecules (known collectively as carcinogens) in tobacco tar can cause mutations in the cells of the throat and lungs.

        • Such mutations can eventually lead to throat cancer, and, in particular, lung cancer - whose incidence correlates very highly with smokers.

      • (b) Carbon monoxide reducing the oxygen-carrying ability of the blood - carbon monoxide combines more strongly with haemoglobin than does oxygen and is slower to be exhaled in the gaseous exchange in the lungs.

        • Consequently, smokers will have less oxygen in their circulatory system.

        • The effect can be damaging in pregnant women, where the foetus in the womb may receive less oxygen through the placenta causing babies to be underweight at birth.

      • (c) Particulates from the combustion of tobacco are also harmful to the lining of the lungs.

        • Blood vessels and the surface of the lungs are damaged leading to lung diseases like bronchitis, emphysema and lung cancer.

  • Be able to evaluate data relating to the correlation between smoking and its negative effects on health.


Some learning objectives for Parts (5) to (8) which overlap with each other

  • You should be aware of the effects of misuse of the legal recreational drugs, alcohol and nicotine.

    • You should know and understand that the misuse of the illegal recreational drugs ecstasy, cannabis and heroin may have adverse effects on the heart and circulatory system.

    • Note that knowledge and understanding of the specific effects of recreational drugs on the body, except for cannabis are not required neither is knowledge of the legal classification of specific drugs required.

    • Drugs may be described as 'hard' or 'soft'.

    • Hard drugs, like heroin, are generally more addictive and potentially harmful, but even soft drugs like cannabis are implicated with mental health effects, heart and circulatory problems and chemicals in the smoke and tar are carcinogenic - probably more than filter cigarettes.

  • Know that cannabis is an illegal drug.

    • Know that cannabis smoke contains chemicals which may cause mental illness in some people.

  • Appreciate that the overall impact of legal drugs (prescribed and non-prescribed) on health is much greater than the impact of illegal drugs because far more people use them.

    • Be Aware and be able to consider and discuss the benefits of medical drugs, the impact of non-medical drugs such as alcohol and the possible misuse of legal drugs.

    • Cannabis users consider such smoking as enjoyable, relaxing and stress relieving and choose to ignore well documented harmful side-effects.

    • Smoking is addictive, due to nicotine, and causes heart disease and lung cancer.

    • Alcohol, is a legal but addictive drug, which slows down the your reaction time to respond to a situation and the more alcohol you take in, the more your judgement is impaired and coordination is reduced. With large amounts of alcohol consumed you may become physically incapable of walking and become unconscious. Continuous excessive drinking (regular 'binge drinking') can result in brain damage and kidney disease.

      • From the millions of people who smoke and drink, eventually many will be suffer the serious side-effects. From days of work and anti-social behaviour and increase the cost to the NHS, our society pays quite a high price for these legal drugs!

  • Know that drugs change the chemical processes in peoplesí bodies so that they may become dependent or addicted to the drug and suffer withdrawal symptoms without them.

    • Know that heroin and cocaine are very addictive.

  •  Know there are several types of drug that an athlete can use to enhance performance.

    • Know that some of these drugs are banned by law and some are legally available on prescription, but all are prohibited by sporting regulations.

    • Know that examples of this type of drug include stimulants that boost bodily functions such as increasing heart rate; and anabolic steroids which stimulate muscle growth - bigger stronger muscles, all taken to make an athlete better at his/her sport.

      • However, apart from being illegal, banning these drugs hasn't prevented some athletes from using them, and are to compete in an unfair way (an ethical issue) AND they also run the risk of harmful side-effects eg steroids can cause high blood pressure.

      • Knowledge of the mode of action of steroids and other performance-enhancing drugs is not required.


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