Nervous System Flashcards
what is an action potential?
The action potential arrives at the synaptic bulb. This causes calcium channels to open and allow calcium ions into the pre synaptic neuron. The calcium ions cause the synaptic vesicles to bind with the cell membrane, so the neurotransmitters diffuse into the cleft until it reaches the post synaptic neuron and bind to the sodium channels. This opens and allows sodium ions to enter the post synaptic neuron and new action potential occurs.
how is action potential generated?
Voltage begins to rise from -60mv. Gates in voltage-gated channels open. Influx of Na+ ions into axon membrane. This is depolarization. This causes action potential in that section of the neurone. Sets off depolarisation in next section of neurone. Approx +30mv when the Na+ channels close. Gates in K+ gated channels open. K+ ions flow into membrane (slower that Na+ influx). Potential difference returns to -60mv. This is repolarisation.
