NROSCI 0081 Lecture Notes - Lecture 4: Myelin, Sodium-Potassium Alloy, Threshold Voltage
Document Summary
Action potential is a large change in the membrane potential rising phase (potential is positive), falling (potential returns to resting), and undershoot (neuron is briefly more negative than resting) Furthest away from 0mv has the biggest diff in polarization. Nerve signal/action potential= electrochemical message of neurons: begins at axon hillock, all or none , varied by changing the frequency of signal conduction, active process requires atp, non-decremental, short time pd (less than 1 msec) Threshold voltage voltage gated na and k ion channels are signaled to open; makes the neuron more positive; as neuron becomes more positive because na is coming in, voltage-gated k channels open. Propagation transmission of action potential down the axon. Myelin insulating material fats and proteins. Sheath = has gaps called nodes of ranvier: action potential is regenerated at each node this is called salutatory conduction. Faster than unmyelinated action potential propagation, saves e(cid:374)ergy, ap"s depolarize the (cid:373)e(cid:373)(cid:271)ra(cid:374)e o(cid:374)ly at (cid:374)odes.
