Exam 2 Flashcards
Subthreshold V subthreshold potentials, implication on AP
Subthreshold will not create AP
Threshold will create AP
the higher the stimulus, the faster the AP will fire
Cardiac AP’s compare/contrast to neuron
Cardiac action potential are prolonged by the slow opening of V-G Ca++ channels
longer depolarized state will mean contraction will have longer time to push through heard
AP propogation factors
Length of nerve(distance covered)
Diameter of nerve(larger is faster/less resistance)
Insulation of nerve(more myelin sheath is faster)
How is myelin formed?
schwann cell grows and wraps around cell then water is squeezed out of schwann cell(oligodendrocyte in CNS) to form sheath
How are action potential propagated with myelin
Saltatory conduction
Na channels influx at node of ranvier(high density of Na channels)
Myelin prevents leaking electrical signal so “jumps” from node to node
Under myelin there are no channels so less Na/K pump ATP used so less prone to ischemia
myelin also adds robustness to cell preventing injury
(40 lecture 2)