Chemotherapy - PowerPoint

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					Chemotherapy
 Assumption of the Biological
         Approach
• The biological approach is interested in
  how behaviour is influenced by chemical
  imbalances in the brain

• Chemotherapy tries to correct these
  imbalances
What are these key terms? Type
  your answer into the box.
      Neuron


      Synapse



Neurotransmitter


   Antagonists

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        Did you get them right?
Neuron = a nerve cell, which transmits signals through the
  nervous system. Uses electrical impulses and chemicals.

Synapse = the gap between two neurons, chemicals pass
  across the gap to stimulate an electrical impulse in the
  next neuron

Neurotransmitter = chemical substance which transmits
  messages across a synapse, by fitting into receptor sites
  and stimulating the next neuron

Antagonists = drugs which reduce the activity of a particular
  neurotransmitter, usually by blocking the receptor sites
      Watch the animation
• On the next slide you will see an
  animation to recap how messages are
  transmitted across the synapse

• I’m sure you already know this… let this
  jog your memory!



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Vesicles release neurotransmitter
into synaptic cleft
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Neurotransmitter binds to
receptors & activates them
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Enzymes are released to break
down the neurotransmitter
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Excess neurotransmitter is taken
up by the pre-synaptic neurone
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Vesicles are replenished with new
& reused neurotransmitter
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        Antipsychotic drugs
• These are a form of major tranquilliser used
  to treat schizophrenia.

• Before they were introduced in the 1950s
  schizophrenia was seen as an untreatable
  disorder and a diagnosis usually led to a stay
  in a mental institution.

• These drugs were a major breakthrough,
  where other physiological therapies (including
  ECT and Insulin shocks) had failed.
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        Antipsychotic drugs
• These are also known as CONVENTIONAL
  ANTIPSYCHOTICS and they reduce
  psychotic symptoms

• They also produce neurological symptoms
• An example is a drug called chlorpromazine

• CONVENTIONAL ANTIPSYCHOTICS
  reduce the positive symptoms of
  schizophrenia, but don’t affect the negative

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        Antipsychotic drugs
• As an excess of the neurotransmitter
  dopamine has been linked to the symptoms of
  schizophrenia, these drugs bind to dopamine
  receptors and block the build up of dopamine.
  The post-synaptic neuron is not stimulated
  and the symptoms are reduced.

• It is thought that the parts of the brain
  linked too schizophrenia (through too much
  dopamine) are in the cerebral cortex and
  limbic systems
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         Antipsychotic drugs
• Antipsychotic drugs reduce symptoms such as
  hallucinations and delusions by sedating the parts of
  the brain responsible for their occurrence.

• Another system linked to dopamine is responsible for
  motor functions

• This system can degenerate, becoming the disorder
  known as Parkinson’s disease.

• Symptoms include tremors, loss of balance, rigidity in
  muscles, and difficult breathing
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        Antipsychotic drugs
• Unfortunately for schizophrenia sufferers,
  neuroleptics can produce Parkinson’s disease-
  like symptoms as a side effect

• This is because the drugs interfere with the
  dopamine in these areas too

• Some schizophrenics are reluctant to take
  these drugs as a result

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       Antipsychotic drugs
• Although these Parkinson’s symptoms
  tend to be temporary, prolonged use of
  conventional anti-psychotics can lead to
  tardive dyskinesia

• Look up this disorder – why is it linked
  to schizophrenia?


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          Antipsychotic drugs
• Other side effects include…

• Windgassen (1992)
  –   50% report sedation
  –   18% have poor concentration
  –   16% suffer a reduction in salivation
  –   16% get blurred vision


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          Antipsychotic drugs
• However, there is a silver lining!!

• Clozapine is a drug that has been recently
  introduced

• It produces fewer side effects than other drugs

• This has also improved both the positive and
  negative symptoms of schizophrenia

• 30-50% improve whilst on the drug

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              Clozapine
• However, 2% develop a potentially fatal
  blood disorder and so they need to be
  monitored

• Clozapine is also more expensive than
  other drugs



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      Antidepressant Drugs
• Depression is a mood disorder where
  the patient feels low (don’t worry – we
  go into more detail later in the course)

• This low feeling is connected to a low
  level of the neurotransmitter serotonin
  in the synapse between nerve cells.


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     Antidepressant Drugs –
         How they Work
• Reducing the rate of reabsorption
• Blocking the enzyme that breaks down
  the neurotransmitter
• Either action would increase the amount
  of neurotransmitter available to
  transmit impulses to neighbouring cells.



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     Antidepressant Drugs –
         How they Work
• Selective Serotonin Reuptake Inhibitors
• SSRIs - Eg PROZAC
• These drugs stop Serotonin being
  reabsorbed back into nerve cells.
• Because it is there longer it can pass on
  more impulses.



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        Antianxiety drugs
• Anxiety and stress are commonly
  treated by Benzodiazepines (BZs) eg
  Valium.

• They work on the Central Nervous
  System



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       Antianxiety Drugs –
         How BZs Work
• Increase the activity of GABA (a
  neurotransmitter) which naturally
  reduces anxiety.
• GABA locks on to receptor cells and
  opens up a channel allowing chloride ions
  into the neuron, making it harder to be
  stimulated and slowing down its activity.
• The result is a feeling of relaxation

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      Antianxiety Drugs –
  How Beta-Blockers(BBs) Work
• Reduce activity of adrenaline and
  noradrenaline (hormones)
• Bind to receptors on target organs (eg
  heart) making them harder to stimulate
  and so reducing arousal – lower blood
  pressure and less anxiety
• Used by snooker players and musicians


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    Effectiveness of Chemotherapy
•   Popular with patients – easy to use
•   Side-effects
•   Antipsychotics – tardive dyskinesia
•   Antidepressants – increased suicide risk
•   Effective in reducing symptoms –
    compared to placebos


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