Recreational drugs

• Endorphins and enkephalins are natural painkillers
• Heroin has depressant effects on the CNS- slows down activity
• Heroine brakes down into morphine in body
• Heroin injected intravenously straight into bloodstream 
• Endorphin and morphine have similar shape so can bind to the same opioid receptors in brain  
• Dopamine also released when we eat food or have sex
• Morphine has much higher effect the normal endorphins 
• Agonist is a drug that binds to a receptor and activates it.
• Tolerance is when the synapse becomes physically effected has to take increased amounts of recreational drug to get the same high
• Dependence is when the body needs the drug to function normally, withdrawal symptoms occur if not taken
• Cocaine is an addictive drug that is used to treat pain and depression.
• It is taken recreationally for its stimulating effects; it speeds up the body e.g. heart rate.
• Cocaine is very fast acting and has immediate effects on neural transmission within the brain
• Cocaine works on the reward pathway and dopamine receptors in the brain
• Cocaine draws on the idea that there is reuptake by the presynaptic neuron of neurotransmitter left in the synaptic gap.
• Cocaine blocks the binding site on the reuptake receptor, or transporter molecule, and stops the reuptake of dopamine back into the presynaptic neuron.
• This blocking of reuptake means there is excess dopamine in the synapse because it is not being reabsorbed.
• This excess of dopamine leads to over-stimulation at the postsynaptic receptors.

  Therefore there is more dopamine than usual creating intense feelings of pleasure, or euphoria.
• The continuous binding of dopamine to the dopamine receptors is overstimulating and negatively affects the neural transmission.
• Overtime the dopamine receptors become damaged, changing shape which prevents neurotransmitters binding successfully.
• The number of dopamine receptor sites will also decrease.
• A person becomes addicted because they crave the intense pleasure experienced, due to activation of the dopamine reward pathway, and therefore want to take the drug again because it is rewarding
• Addiction occurs when the brain has been exposed to an artificial stimulus (drug) repeatedly causing changes in the brain structure and function.
• When someone takes a drug their body adapts to cope with the presence of the drug. This adaptation causes tolerance.
• Physical withdrawal symptoms include nausea, vomiting, sweating, trembling, insomnia, headaches and muscle pain.