HMB200H1 Chapter Notes - Chapter 4.3: Axon Hillock, Threshold Potential, Resting Potential
Document Summary
Neurons receive information from dendrites & cell body: how does it integrate all information, and send out as 1 impulse. Motor neurons are ideal for studying information integration: receive inputs from multiple sources (skin, joints, muscles, and the brain) Eccles experiment: insert microelectrode into vertebrate animal"s spinal cord, right beside a motor neuron"s cell body, placed stimulating electrode on axons of sensory nerve fibers that enter spinal cord. Teased sensory nerves apart stimulate one fiber at a time. Stimulating certain pathways produced different voltage-related messages: excitatory postsynaptic potentials (epsp): the postsynaptic neuron depolarizes. Brings membrane towards threshold potential, increasing chances of action potential in that neuron: inhibitory postsynaptic potentials (ipsp): the postsynaptic neuron hyperpolarizes. Decreases the charge, away from the threshold potential & decreases chances of action potentials. Epsp & ipsp only last a few milliseconds, before decay & membrane resting potential is restored: epsp"s open na+ channel (influx of na, ipsp"s open k+ or cl- channel.
