while letting nutrients pass through to neurons The Electrical Activity of

While letting nutrients pass through to neurons the

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while letting nutrients pass through to neurons The Electrical Activity of Neurons resting potential - in the electrical activity of neurons, the internal difference of the sodium ions outside of a cell and the negatively charged protein ions inside the cell action potential - a nerve impulse resulting from the depolarization of an axon's cell membrane depolarization - the reversal of the resting potential of a neuron's cell membrane that produces the action potential absolute refractory period - a time of recovery during which a cell membrane is not excitable and cannot generate another action potential all-or-none law - the fact that an action potential is not proportional to the intensity of stimulation; a neuron either fires with maximum intensity or it does not fire (compare with graded potential ) action potential threshold
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- the intensity of stimulation (excitatory minus inhibitory) needed to produce an action potential graded potentials - a change in the electrical potential of a neuron that is proportional to the intensity of the incoming stimulation, but not sufficient to produce an action potential myelin sheath - a fatty insulating substance on the axon of some neurons that increases the speed of neural transmission How Neurons Communicate: Synaptic Transmission synapse - the microscopic space between neurons over which the nerve impulse is biochemically transmitted synaptic clef - a tiny gap between the axon terminal of one neuron and the dendrite of the next neuron neurotransmitters - chemical substances that are released from the axons of one neuron, travel across the synaptic space, and bind to specially keyed receptors in another neuron, where they produce a chemical reaction that is either excitatory or inhibitory synaptic vesicles - chambers within the axon that contain the neurotransmitter substance receptor sites - protein molecules on neurons' dendrites or soma that are specially shaped to accommodate a specific neurotransmitter molecule reuptake - process whereby transmitter substances are taken back into the pre-synaptic neuron so that they do not continue to stimulate postsynaptic neurons acetylcholine (ACh) - an excitatory neurotransmitter that operates at synapses with muscles and is also the transmitter in some neural networks involved in memory dopamine
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- an excitatory neurotransmitter whose overactivity may underlie some of the disordered behaviours seen in schizophrenia Serotonin - a neurotransmitter that seems to underlie positive mood states; underactivity may be a factor in depression endorphins - natural opiate-like substances that are involved in pain reduction neuromodulators - neurotransmitter substances that are released by neurons and circulate within the nervous system to affect the sensitivity of many neurons to their natural transmitter substances Applications: Understanding How Drugs Affect Your Brain THE NERVOUS SYSTEM sensory neurons - specialized neurons that carry messages from the sense organs to the spinal cord and brain motor neurons
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