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61 Cards in this Set
- Front
- Back
functions of nervous system
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communication
homeostatis *sensation, integration, reaction* |
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anatomical divisions of nervous system
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central nervous system (CNS)
peripheral nervous system (PNS) |
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central nervous system (CNS) parts
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brain
spinal cord |
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peripheral nervous system (PNS) parts
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nerves (cranial, spinal)
ganglia (sensory, autonomic) |
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peripheral nervous system (PNS) divisions
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sensory division
motor division |
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sensory divisions (in PNS)
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somatic sensory
visceral sensory |
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motor sensory divisions (in PNS)
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somatic motor
visceral motor (aka: autonomic motor) |
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visceral motor divisions (in PNS)
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sympathetic
parasympathetic |
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viscerosensory functions
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sensation from internal organs
"viscus" = organs example: nausea |
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somatosensory functions
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sensation from the surface/skin
"soma" = body |
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visceromotor (autonomic) functions
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motor (movement) to cardiac muscle, smooth muscle, and glands
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somatomotor fucntions
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motor (movement) to skeletal muscles
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characteristics of a neuron
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excitability
conductivity secretion |
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excitability
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respond to stimuli
(mechanical, chemical, electrical) |
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conductivity
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quickly transmit electrical signals over long distances
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secretion
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releases a neurotransmitter to affect another cell
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functional classes of neurons
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sensory/afferent
interneurons/association neurons motor/efferent |
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sensory/afferent neurons
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neurons conducts signals from receptors TO the CNS
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interneurons/association neurons
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confined ONLY to the CNS
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motor/efferent neurons
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neurons conduct signals FROM the CNS to effectors
effectors = muscles and glands |
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two types of cell bodies in the CNS
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interneurons
motor *most cell bodies are in the CNS* |
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two types of cell bodies in the PNS
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sensory
visceromotor |
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nissl bodies
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concenrations of ROUGH ER
responsibe for MAKING PROTEINS needed by the cell |
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neurofibrils
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bundles of ACTIN FILAMENTS that SUPPORT the cell
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dendrites
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part on neuron that usually RECEIVES INCOMING INFORMATION
carries information to the cell body |
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axon (nerve fibers)
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carries information away from the cell body
SINGLE process that transmits an action potential sends signal to target(s) |
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initial segment of axon
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MOST SENSITIVE to changes in membrane potential
first part of cell to DEPOLARIZE |
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axon collaterals
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branches that allow one neuron to contact multiple targets
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axon terminals
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where axons terminate on their targets
(neurons, muscles, glands) |
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resting potential
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base line charge of neuronal membrane
outer surface of membrane has more positive charge high sodium [Na+] outside of membrane |
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polarity
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difference in charge across the membrane
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depolarization
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neuron is stimulated
Na+ channels in membrane open Na+ follows gradient and enters cell POLARITY across membrane DECREASES if membrane is depolarized beyond threshold, action potential will pass down the entire length of the axon |
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repolarization
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after fixed time, Na+ channels close
Na+ exits cell RESTING POLARITY is re-established |
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organization of cell bodies
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neurons with common functions and destinations stick together
gray matter is cell bodies |
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gray matter
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cell bodies
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white matter
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bundles of axons
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gray matter in CNS
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gray = nuclei = cell bodies with common function
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white matter in CNS
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white = tracts = axons with common function
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gray matter in PNS
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grey = ganglia = cell bodies with common function
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white matter in PNS
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white = nerves = axons with common destination
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neuron shapes
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distinguished by number of processes off cell body
*number depends on the number of dendrites* *there is always just one axon* multipolar, bipolar, unipolar |
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multipolar neuron
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many dendrites
MOST COMMON TYPE many different functions |
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bipolar
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one dendrite
rare SPECIAL SENSES (vision, hearing, smell) |
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unipolar
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one process is both dendrite AND axon
very common GENERAL SENSORY cells in dorsal root and cranial nerve ganglia |
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glial cells in the CNS
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astrocytes
ependymal cells microglial cells oligodendrocyte |
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astrocytes
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FORM TUNNELS FOR BLOOD VESSELS WITHIN THE CNS
look like multipolar neuron remove ions from extracellular space form scar tissue when neurons are injured (glial cells in the CNS) |
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ependymal cells
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secretes cerebrospinal fluid (CSF)
line the ventricles (glial cells in the CNS) |
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ventricles
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fluid-filled spaces in the brain
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microglial cells
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phagocytic cell
clean up debris in nervous tissue macrophages of CNS tiny (glial cells in the CNS) |
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pligodendrocyte
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forms myelin around large axons in the CNS
(glial cells in the CNS) |
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glial cells in the PNS
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satellite cells
schwann cells |
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satellite cells
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surround cell bodies in the PNS and separate them from the surrounding tissue
found in ganglia (glial cells in the PNS) |
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ganglia
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clusters on nerve cells in the body
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schwann cells
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associated with ALL axons in the PNS
myelinate the large axons (glial cells in the PNS) |
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how schwann cells myelinate large axons in the PNS
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each schwann cell myelinates PART of a SINGLE axon
takes many cells to cover entire axon there are gaps between adjacent schwann cells |
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myelinated axons
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"cinnamon bun"
axon is in middle glial cell wraps around it and insulates it |
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myelination
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the THICKER the axon,
the THICKER the myelin, and the FASTER the action potential myelin speeds the action potential |
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nodes of ranvier
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short segments of the axon where there is NO myelin
ONLY sites that CAN depolarize |
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demyelination
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myelin represses, gets thinner and shorter
parts of the axon's membrane is newly exposed action potential gets slower at first then eventually comes to a complete stop |
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unmyelinated axons
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"push pencil into side of bread dough"
myelin still goes around pencil, but not around and around and around like a myelinated axon (cinnamon bun) |
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unmyelinated fibers
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thin axons are unmyelinated axons in the PNS
protected with schwann cells single schwann cell "surrounds" many axons |