NROSCI 0081 Lecture Notes - Lecture 4: Threshold Voltage, University Of Manchester, Membrane Potential
Document Summary
Action potential: (aka neuronal firing) an electrical signal produced within neurons by rapid movement of ions across cell membrane. Threshold voltage- the membrane potential (voltage) a neuron must have for voltage-gated ion channels to open. Absolute refractory period- period of time in which a new action potential can not be generated. 1-2 msec after initiation of action potential and immediately after it finishes. Makes action potentials travel along axons in one direction. Relative refractory period- period of time in which a new action potential can be generated but only with a signal greater than threshold. Makes rate of firing (frequency of action potentials) related to intensity of stimulation: rate of firing important for coding intensity of stimuli. For action potential to occur, voltage-gated ion channels must open. These (cid:272)ha(cid:374)(cid:374)els ope(cid:374) whe(cid:374) (cid:374)euro(cid:374)"s (cid:373)e(cid:373)(cid:271)ra(cid:374)e pote(cid:374)tial (cid:272)ha(cid:374)ges & rea(cid:272)hes threshold voltage. If threshold not reached, channel does not open. Na+ channels open inactivated (refractory) closed.
