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Title: Discuss signal conduction through a neuron from incoming excitation to signal initiation in the post Post by: Babygal on Oct 13, 2010 Discuss signal conduction through a neuron from incoming excitation to signal initiation in the post synaptic cell. Include the roles of graded and action potentials and the synapses.
Use the words below write an essay putting them into the correct order. define and describe i.e. what it is , where is it and what it does? dendrite/cell body potentials vary in strength special summation positive feedback suprathreshold signal resting membrane potential chemical or electrical stimuli all or none absolute refractory Na+ activation gate conduction rate K+ efflux This is what I have written so far: The nucleus of a neuron is located in the cell body. Extending out from the cell body are processes called dendrites and axons. These processes vary in number & relative length. the inside of the neuron is slightly negative relative to the outside. This difference is referred to as the Resting Membrane Potential. The cell body receives chemical or electrical stimuli and initiates a graded potential. The graded potential varies in strength and is enhanced or diminished by special summation. Define special summation This travels across the cell body. In the axon hillock if graded potential is suprathreshold signal this is called “all or none”. This will initiate an action potential and Na+ activation gates open. The Na+ influx causes positive feedback. Mention depolarization This cause inactivation gates to close. Define action potential- Action potential propagation occurs in one direction because the recently depolarised area of the membrane is in absolute refractory period and cannot generate an action potential. Once depolarization reaches threshold, an action potential is generated. If depolarization does not reach threshold, no action potentials are generated. This is referred to as “all or none”. During an action potential, the membrane potential rapidly depolarizes and reverses such that the inner membrane surface is more positive relative to the outer membrane surface. The membrane potential then repolarises back to resting membrane potential. If the stimulus leads to a membrane depolarization that is less negative (more positive) than the threshold value, it is said to be supra-threshold. In general, supra-threshold stimuli lead to action potentials. Title: Discuss signal conduction through a neuron from incoming excitation to signal initiation in the post Post by: bio_man on Oct 13, 2010 Perfect ;).
This should assist you even further: 1) http://www.learn.ppdictionary.com/resources/ActnPtnlPropagation.htm (http://www.learn.ppdictionary.com/resources/ActnPtnlPropagation.htm) 2) http://www.learn.ppdictionary.com/resources/nerveImpulse.swf (http://www.learn.ppdictionary.com/resources/nerveImpulse.swf) 3) http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120107/anim0013.swf::Voltage%20Gated%20Channels%20and%20the%20Action%20Potential (http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120107/anim0013.swf::Voltage%20Gated%20Channels%20and%20the%20Action%20Potential) |