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What does a motor neuron do?
- it receives excitation from other neurons and conducts impulses from its soma in the spinal cord to muscle or gland cells
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What do sensory neurons do?
- are specialized at one end to be highly sensitive to a particular type of stimulation, such as touch information in the skin
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What are dendritic spines?
- short outgrowths that increase the surface area available for synapses
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What is an afferent axon?
- axon that brings information into a structure
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What is an efferent axon?
- an axon that carries information away from a structure
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What is an interneuron or intrinsic neuron?
- when a cell's dendrites and axon are entirely within a single structure
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What are the 5 different kinds of glia?
- - astrocytes
- - microglia
- - oligodendrocytes
- - schwann cells
- - radial glia
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What are astrocytes ?
- star-shaped glia that wrap around the presynaptic terminals of several axons, presumably a functionally related group.
- they take up chemicals released by those axons and later release them back to the axons, helping synchronize the activity of axons
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What are microglia?
- very small glia cells that remove water material as well as viruses, fungi, and other microorganisms.
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What are oligodendrocytes?
- glia cells that are in the brain and spinal cord that build the myelin sheaths that surrounds and insulates certain vertebrate axons
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What are schwann cells?
- glia cells in the periphery of the body that build the myelin sheaths that surround and insulate certain vertebrate axons
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What are radial glia?
- a type of astrocyte, they guide the migration of neurons and the growth of their axons and dendrites during embryonic development
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What is the blood brain barrier?
- the mechanism that keeps most chemicals out of the vertebrate brain
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What is active transport?
- a protein-mediated process that expends energy to pump chemicals from the blood into the brain
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What is an electrochemical gradient?
- when there is a difference in electrical charge between the inside and outside of the cell
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What is polarization?
- a difference in electrical charge between two locations
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What is a resting potential?
- the difference in voltage in a resting neuron
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What is the sodium-potassium pump?
- a protein complex that repeatedly transports three sodium ions out of the cell while drawing two potassium ions into the cell
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What is a concentration gradient?
- the difference in distribution of ions across the membrane
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How do local anesthetic drugs work?
- they attach to the sodium channels of the membrane, preventing sodium ions from entering, thus blocking action potentials
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How do general anesthetics work?
- they decrease brain activity by opening certain potassium channels wider than usual, thus preventing most action potentials
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What is the "all-or-none law"?
- the amplitude and velocity of an action potential are independent of the intensity of the stimulus that initiated it
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What is the refractory period?
- a period during which it resists the production of further action potentials
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What is the absolute refractory period?
- when the sodium gates are firmly
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