From node node until reaching terminal end conduction

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: l patch prd of membrane, not entire neuron) of • Absolute refractory prd= time btw start of AP & return to RMP • Relative refractory prd= time btw RMP & end of hyperpolarization Signal Conduction in unmyelinated fibers= chain reaction of AP’s chain down entire fiber (or depolarizing ‘segments’ of membrane) until signal reaches terminal end signal • Nerve signal= traveling wave of excitation made by series of AP’s ation • Can’t travel ‘up’ axon because of refractory prd Signal Conduction- Myelinated Fibers Signal Nodes of Ranvier are ‘packed’ w/ voltage-regulated ion gates since myelin sheaths of internodes ‘block’ Na from entering since • Thus, signal ‘jumps’ from node-node until reaching terminal end Conduction very rapid down each internode, but does weaken • NR spaced ~1mm apart so new AP’s are generated per/node • Saltatory conduction= propagation of a nerve signal that ‘jumps’ propagation from node to node from Synapses- pre & postsynaptic neurons • Electrical (gap junctions) & chemical synapses chemical • Neurotransmitters allow c.synapses to ‘communicate’ Neurotransmitters to • Presynaptic neuron houses synaptic vesicles & postsynaptic Presynaptic neuron has receptors & ligand-regulated ion gates ligand-regulated Neurotransmitters & Regulated Messengers Messengers 100+ neurotransmitters discovered so far: ACh & 3 classes 100+ according to chemical composition according • As science progresses, neurotransmitters, hormones, & As other messengers are becoming difficult to distinguish other Typical neurotransmitter= sm organic compound synthesized sm by pre-, released into s.cleft, bind to sites on post-, & alter physiology of 2nd cell physiology • Receptor determines effect of neurotransmitter has on post• Same chemical has many different types of receptors, & so, a Same neurotransmitter doesn’t have same effect ev...
View Full Document

Ask a homework question - tutors are online