PSYCH261 Chapter Notes - Chapter 2: Reflex Arc, Sensory Neuron, Motor Neuron
16 Jan 2018
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Ex: in a leg flexion reflex, a sensory neuron excites a second neuron, which in turn excites a motor neuron, which excites a muscle. Reflex arc: the circuit from sensory neuron to muscle response. Because transmission through a reflex arc is slower than transmission through an equivalent length of axon, sherrington concluded that some process at the synapses delays transmission. An impulse travelling through a synapse in the spinal cord is slower than one traveling a similar distance along an uninterrupted axon. Temporal summation: the phenomenon that states repeated stimuli within a brief time have a cumulative effect (several impulses from one neuron over time) It is the combined effect of quickly repeated stimulation at a single synapse. Excitatory postsynaptic potential (epsp): an excitatory graded potential (depolarizing) It results from a flow of sodium ions into the neuron. Sherrington also found that synapses have the p(cid:396)ope(cid:396)ty of (cid:862)spatial su(cid:373)(cid:373)atio(cid:374)(cid:863) summation over space.
