20. Action Potentials Can travel up to 100 meters/second Usually 10-20 m/s 0.1sec delay between muscle and sensory neuron action potential
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Notes de l'éditeur
Charged particles are called ions. Negatively charged ones are ‘anions’, while positive ones are ‘cations’. Proteins are negatively charged particles and they remain inside the cell
Ion channel : A specialized protein molecule that permits specific ions to enter or leave the cell. Voltage-dependent ion channel : An ion channel that opens or closes according to the value of the membrane potential. Depolarization: Reduction (toward zero) of the membrane potential of a cell from its normal resting potential. Normal depolarizing events are termed EPSPs – excitatory post-synaptic potentials – and result from opening of Na+ channels. Hyperpolarization: An increase in the membrane potential of a cell, relative to the normal resting potential. Hyperpolarizing events are termed IPSPs – inhibitory post-synaptic potentials – and result from opening of Cl- channels (Cl- higher outside than in, so flow in and make cell more negative). Also can result from opening K+ channels. Action potential : The brief electrical impulse that provides the basis for conduction of information along an axon. Threshold of excitation : The value of the membrane potential that must be reached to produce an action potential. Cable properties : The passive conduction of electrical current, in a decremental fashion, down the length of an axon. Saltatory conduction ; Conduction of action potentials by myelinated axons. The action potential appears to jump from one node of Ranvier to the next. All-or-none law : The principle that once an action potential is triggered in an axon, it is propagated without decrement to the end of the fiber. Rate law : The principle that variations in the intensity of a stimulus or other information being transmitted in an axon are represented by variations in the rate at which that axon fires.
