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35 Cards in this Set
- Front
- Back
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2 parts of nervous system
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1. CNS
2. PNS |
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CNS includes the ___ and ____ _____, which includes nuclei and tracts.
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brain; spinal cord
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3 components of PNS
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1. nerves
2. ganglia 3. nerve plexuses |
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3 parts of neuron
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1. cell body
2. dendrites 3. axon |
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4 things contained in cell body
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1. nucleus
2. Nissl bodies 3. neurophils 4. other organelles |
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Dendrites receive _______, and axon conducts ______ __________ away from the cell body.
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stimuli, nerve impulses
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Nerve
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collection of axons in PNS
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Sensory/afferent neuron
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pseudounipolar and conducts impulses from sensory receptors into the CNS
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Motor/efferent neuron
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multipolar and conducts impulses from CNS to effector organs
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Interneurons/association neurons
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located entirely within CNS
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Somatic motor nerves
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innervate skeletal muscle
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Autonomic nerves
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innervate smooth muscle, cardiac muscle, and glands
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2 types PNS supporting cells
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1. Schwann cells
2. satellite cells |
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4 types CNS supporting cells
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glial cells
1. oligodendrocytes 2. microglia 3. astrocytes 4. ependymal cells |
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Schwann cells
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wrap around PNS axons, forming neurilemma, or Schwann sheath (myelin)
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Myelin sheath
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1. Schwann cells in PNS
2. oligodendrocytes in CNS |
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Astrocytes
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may contribute to blood-brain barrier in CNS
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What regulates permeability of axon membrane to Na+ and K+?
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gated ion channels
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Na+ and K+ channels are _________ regulated.
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voltage
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Na+ and K+ channels open in response to the stimulus of _________.
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depolarization
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The opening of voltage-regulated channels produces an ______ _________.
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action potential
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Resting membrane potential
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-70mV
membrane impermeable to Na+ slightly permeable to K+ |
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Inward diffusion of NA+ causes reversal of membrane potential from ________ mV to ________mV.
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-70, +30
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The opening of K+ channels and outward diffusion of K+ reestablishes resting membrane potential. This is called _________.
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repolarization
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Action potentials are __________ events.
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all-or-none
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What keeps action potentials from running together?
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refractory periods
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Stronger stimuli produce action potentials with ________ frequency.
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greater
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One action potential serves as the stimulus for production of _________ in the axon.
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the next action potential
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In ___________ axons, action potentials are produced fractions of a micrometer apart.
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unmyelinated
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In myelinated axons, action potentials are only produced at the ___________.
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nodes of Ranvier
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The _________ conduction of myelinated axons is faster than conduction in an unmyelinated nerve fiber.
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saltatory
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Gap junction
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electrical synapses found in cardiac muscle, smooth muscle, and some regions of the brain
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In chemical synapses, ___________ are packaged in synaptic vesicles and are released by _________ into the synaptic cleft.
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neurotransmitters; exocytosis
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What causes opening of chemically regulated gates of ion channels?
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binding of neurotransmitter to the receptor
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2 types of ACh receptors
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1. nicotinic
2. muscarinic |
