PSL300H1 Lecture Notes - Lecture 16: Neurotransmitter, Neuroglia, Enzyme
Document Summary
Opening na+ channels triggers more na+ channels opening: propagates the impulse down the length of the axon. No action potentials in most cells: majority of cells don"t have excitable na+ channel, can only conduct passive currents, cannot generate its own, don"t have axons & subsequent connections. Definition: cell that have the ability to generate membrane potentials. Signals are weakened through process of propagation. Length constant ( : definition: how quickly a potential decays to 0, as a function of distance travelled, the amount of distance the potential can travel, before the signal decays to 37% of its original strength) The single most efficient way to increase conduction velocity: myelin sheathes insulate the axon prevent current loss. By: glial cells & oligodendrocytes: glial cells schwann cells (pns, oligodendrocytes cns. Axon surrounded by bilayer schwann cell membranes: around 150 times wrapped around the axon, bilayer w/ low permeability high insulation. Nucleus of schwann cells & oligodendrocytes pushed towards the outside.
