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ACTION POTENTIALS (LO's: (The somatic nervous system., Synapses., The…
ACTION POTENTIALS
LO's:
The somatic nervous system.
Synapses.
The neuromuscular junction.
Excitation-contraction coupling in skeletal muscle
Drugs acting at neuromuscular junction.
Termination structures:
Chemical synaps
Site of neurotransmitter release
Electrical synaps
Gap junction
Neuromuscular junction
MOTOR END PLATE
Where nerve connects to muscle
Contains folds that increase contact area
Potential -70mV
Somatic nervous system
Comp:
Nerves of skeletal muscles
Exterior sense organs
Skin
Only one nerve between system and spinal cord (neuromediator)
SARCOPLASMIC RETICULUM
Area within a muscle that contains calcium
Process of excitation
Action potential arrives
Moves down T tubule
Causes calsium to be released from SR
Toxins:
Prevent the release of acetylcholine
Botulinum
Tetanus
Antiacetylcholinesterase
Cause prolonged stimulation
Sarin gas
Organophosphorus pesticides
Synaptic jump
Process:
Volted gated channels open
Calsium influx
Triggers synaptic vesicles to bind to terminal
Exocytosis of neurotransmitters
Open Na+/K+ channels
Depolarisation of post-synaptic membrane
Neuromediators:
Acetyle choline
Produced by cholinergic nerves
Broken down by Acetylcholinesterase
Receptors:
NICOTINIC
Ligand gated
Acetyl choline
2 Binding sites
Low affinity
High affinity
Allows sodium Na+ influx
Safety factor
Ability of neuromuscular transmission to remain effective under various physiological conditions
Disease
Myasthenia Gravis
Autoimmune
Antibodies block acetylcholine receptors
Muscle weaknes, fatigue