In the animal kingdom, bigger is better right? Well, not always.

What the video to the right and pay close attention to the salamander.

The Salamander secretes a poisonous substance from its skin, killing the frog within seconds.

Drugs

In the nature, plants and animals use toxins and drugs to aid their survival.

However, some animals, including humans, abuse the effects of these toxins.

Humans not only use natural toxins (Kava, Damiana,  Cocaine, Cannabis and Psilocybin) but we also synthesis drugs and toxins (Meth-amphetamines) which create psychedelic effects.

Ecstasy (also called MDMA) is a drug that blocks the Serotonin receptor sites in the synapses in the brain.

This prevents the Serotonin from being absorbed by the receptor molecules. As a result, the level of Serotonin in the synapse increases.

This produces a feeling of wellbeing.

Beta Blockers are drugs that can help people who suffer from angina (chest pain due to a heart condition).

They work by blocking the receptor sites on heart muscle cells so impulses from nerves which would speed up the heart are prevented from passing to the heart.

Prozac is an anti-depressant drug that causes Serotonin concentration to build up in synapses.

The Prozac molecule blocks the re-uptake of Serotonin from a synapse.

This means there is more Serotonin in the brain, bringing people with depression, back to normal levels of emotions.

In order to understand how drugs work, its important to understand what neurotransmitters are and how they operate.

Neurotransmitters are released from the axon endings into the synapse, and excite the opposite neuron.

Serotonin is a neurotransmitters, and is known as pleasure chemicals. Lack of this chemical can lead to feelings of depression.

Questions

1. Define neurotransmitter

2. Addictive drugs are known to influence dopamine levels in the brain.

(i) Briefly explain the role of dopamine in the brain (2 marks)

(ii) Give two ways in which a drug can act to change the effects caused by             neurotransmitters such as dopamine in the brain (2 marks)

3. Explain why Prozac is used for individuals with depression (4 marks)

4. How does ecstasy affect an individual (6 marks). (Ensure you discuss neurological and personality effects).

5.

   (ii) Using information from the table, describe the effect of this drug on reaction

time (2 marks)

    (iii) Explain how this drug causes a change in reaction time (2 marks)