Biology (Drugs& the nervous system)

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  • Biology
    • The nervous system
      • The nervous system allows the body to respond to changes in the environment in a process usually coordinated by the brain
      • Reflex actions are extra-rapid responses to stimuli
      • this process also involves the nervous system but bypasses the brain
      • Receptors
        • groups of specialised cells that can detect changes in the environment called stimuli
        • Receptors are often located in the sense organs, such as the ear, eye and skin
          • Eyes- light sensitive
          • Ears- sound and position of the head
          • Tongue- chemicals in food
          • Nose- chemicals in the air
          • Skin- touch pain temperature and pressure
        • Each organ has receptors sensitive to particular kinds of stimulus
    • Drugs
      • substances that change chemical reactions in the body
      • Medical drugs relieve disease and illness, and are extensively tested before being used
      • Recreational drugs such as alcohol and tobacco are taken by people because they like the effects they have on their bodies, but they may be addictive
        • Cannabis and heroin are illegal recreational drugs that are very addictive
      • Alcohol
        • slows down signals in the nerves and brain (depressant)
        • Small amounts of alcohol help people to relax
        • greater amounts lead to a lack of self-control
        • Drinkers of alcohol may not realise how much they are consuming, and fall ill as a result
        • Long-term effects of alcohol include damage to the liver and brain, and it is often the cause of weight gain
      • Nicotine
        • Nicotine is the addictive substance in tobacco smoke
        • It reaches the brain within 20 seconds and creates a dependency so that smokers become addicted
        • EFFECTS: Heart disease and strokes, miscarriage, premature birth and low birth weight, lung cancer, mouth cancer and throat cancer


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