Post on 09-Feb-2016
description
The effect of drugs on the synapse
• WALT• That different drugs affect the synapse in
different ways• To research different drugs and their
effects on the synapse
Research the following drugs and describe their effects on the
synapse
• Nictoine• Atropine• Betablockers• Curare• Prozac
Drugs and the synapse
• Almost all drugs taken by humans (medicinal and recreational) affect the nervous system.
• From our understanding of the human nervous system we can understand how many common drugs work
Drugs can affect the nervous system in various ways, shown in
this table:Mimic a neurotransmitter Switch on a synapse
Stimulate the release of a neurotransmitter
Switch on a synapse
Open a neuroreceptor channel Switch on a synapse
Block a neuroreceptor channel Switch OFF a synapse
Inhibit the breakdown enzyme Switch on a synapse
Inhibit the Na+K+ATPase pump Stop action potentials
Block the Na+ or K+ channels Stop action potentials
Excitatory drugs:
These amplify the process of synaptic transmission by
1. mimicking the transmitter substance2. stimulating the release of more of the
natural transmitter3. slowing or preventing the breakdown of
the transmitter examples: amphetamines, caffeine, nicotine
Inhibitory drugs:
These decrease the process of synaptic transmission by
1. Preventing the release of the synaptic transmitter
2. Blocking the action of the transmitter at the receptor molecules on the postsynaptic neuron
example: atropine
Agonists/ Antagonists
Agonists:• Drugs that stimulate a nervous system are
called agonists
Antagonists:• Drugs that inhibit a system are called
antagonists
Nicotine
• Nicotine is a similar shape to acytylacholine and so competes with acetylcholine to bind with its receptors
• Once it has bound to the receptors it opens the sodium channels cusasing an action potential to be generated
Atropine
• Parasympathetic antagonists like atropine binds to the acetylcholine receptors but blocks the receptors so inhibiting the muscarinic acetylcholine receptors in parasympathetic system, and are used as eye drops to relax the ciliary muscles in the eye.
Beta Blockers
• Sympathetic antagonists like the beta blockers block the noradrenaline receptors in the sympathetic nervous system.
• They cause dilation of blood vessels in the treatment of high blood pressure and migraines, and reduce heartbeat rate in the treatment of angina and abnormal heart rhythms.
Curare
• Used as a muscle relaxant in abdominal surgery
• It competes with acetylcholine at the neuromuscular junctions preventing the muscles from contracting.
• South American Indians use it as a poison to catch animals by smearing theor arrow tips with it
Prozac• Serotonin is a neurotransmitter in the brain• Prozac works by inhibiting the uptake of
serotonin• This means there is an increased
concentration of serotonin at the synaspes• Making the patient feel happier and more
relaxed!!