PS263 Chapter Notes - Chapter 2: Nucleus Accumbens, Metabotropic Receptor, Morphine
Document Summary
Sherrington"s research: charles scott sherrington inferred that the specialized narrow gap separating the neurons (discovered by cajal) is actually a synapse, sherrington studied reflexes i. e. automatic muscular responses. In a leg flexion reflex; a sensory neuron excites a second neuron excites a motor neuron. Sherrington observed the following: reflexes are slower than conduction along an axon. He found that speed of conduction through reflex arc was never more than 15 m/s. Action potential velocities along sensory/motor neurons are 40 m/s. Temporal summation: summation over time: proposed that subthreshold excitation can combine with second excitation and so on to produce an action potential. Excitatory postsynaptic potential (epsp) graded depolarization: during epsp, sodium gates in membranes open. If an epsp does not cause cell to reach threshold, it decays: a quick sequence of epsp"s combine to exceed threshold & produce temporal sum. Inhibitory postsynaptic potential (ipsp) temporary hyperpolarization of a membrane: during ipsp, potassium & chloride gates open.
