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Neuromuscular Synaptic Muscle Calcium Ion Synapse Acetylcholine Describe

Muscle contraction begins when an action potential at the neuromuscular junction opens Ca2+ channels, releasing acetylcholine into the synaptic cleft. Acetylcholine bindings open Na+ channels on the sarcolemma, causing depolarization; acetylcholinesterase then breaks down acetylcholine to stop contraction.

La contracción muscular se inicia cuando un potencial de acción en la unión neuromuscular abre canales de Ca2+, liberando acetilcolina en la hendidura sináptica. La acetilcolina se une a receptores en el sarcolema, abriendo canales de Na+ y causando despolarización; la acetilcolinesterasa luego descompone la acetilcolina para detener la contracción.

Front Describe the events that occur at a neuromuscular junction in order to cause (& stop) a muscle contraction.
Back Neuromuscular junction:
  • When AP arrives at neuromuscular junction, it stimulates calcium ion channels to open
  • Calcium ions diffuse from synapse into synaptic knob where they cause synaptic vesicles to fuse with presynaptic membrane
  • Acetylcholine is released into synaptic cleft by exocytosis and diffuses across synapse
  • It binds to receptors on sarcolemma, opening sodium ion channels, resulting in depolarisation
  • Acetylcholine is broken down by acetylcholinesterase, preventing the muscle from being overstimulated

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