BIOL 111 Lecture Notes - Lecture 59: Tetrodotoxin, Procaine, Skeletal Muscle

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23 Jul 2016
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BIOL 111 Organismal Biology
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7.!acetylcholine is broken down by enzyme, acetylcholinesterase, and taken back
to the axon terminal for recycling
!!if acetylcholinesterase were inactivated the muscle would contract
indefinitely
Drugs that Affect Excitatory Neurotransmitters
!nerve gases (e.g. Sarin gas)
o!nerve gases inhibit acetylcholinesterase
o!acetylcholine is not broken down and remains in the synapse
o!skeletal muscles would contract uncontrollably causing paralysis
!anti-depressants (e.g. Prozac)
o!anti-depressants block the re-uptake of excitatory neurotransmitters (mainly
serotonin)
o!serotonin stayed in the synapse longer and impulse is transmitted more frequently
Drugs that Cause Inhibitory Effects
!anti-anxiety drugs (e.g. Xanax, Valium)
o!these drugs mimic the action of natural inhibitory neurotransmitters
o!they will cause the postsynaptic cells to open Cl- channels which will cause
hyperpolarization
o!greater stimulus is therefore required to reach threshold
!tetrodotoxin
o!blocks the Na+ channels and prevents depolarization
o!released by a wide variety of animals
o!tetrodotoxin causes death by diaphragm paralysis
!anaesthetics (e.g. Novocain)
o!inhibit local movement of Na+ through channels
o!prevent depolarization
The Muscular System
!muscle tissue is present in all animals except sponges
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