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36 Cards in this Set

  • Front
  • Back
Nissl body
elaborate type of rough ER
intermediate filament protein in cytoplasm of nucleus
cluster of neuron cell bodies in PNS
cluster of neuron cell bodies in CNS
bundle of axons in CNS
bundle of axons in PNS
axonal terminals
branches at ends of telondendria which end in bulbous ends that store and release neurotransmitters
-aka sheath of schwann
-cytoplams of nucleus of schwann cell squeezed outside the myelin sheath
nodes of ranvier
gaps between myelin
delicate CT, covers axon
coarse CT, covers fasicle
tough CT, covers nerve/tract
Biosynthetic Center
cell body - perikaryon - amitotic
Receptive Center
Supporting Cells in CNS
astrocytes: most abundant, wrap around neurons, involved in forming BBB, regulate brain function
-Microglia: macrophages
-Ependymal cells: ciliate columnar cells, line ventricles, circulate CSF
-oligodendrocytes: myelinate axons of neurons
Supporting Cells in PNS
-schwann: myelinate axons of neurons
-satellite: surround cell bodies of neurons and control chemical environment
Why myelinated axons in CNS can NOT regenerate when severed
-neurons in CNS: no neurilemma to guide growth of severed axon
-microglia in CNS can't clean up debridement
-presence of growth-inhibiting proteins in CNS inhibit regeneration of a severed axon
Why axons in PNS CAN regenerate when severed
-cells of immune system clean up debridement, set stage for regeneration
-regeneration tube: formed by neurilemma of schwann cells that guides regeneration of severed axon
Why impulses are conducted faster in larger myelinated axons than in smaller unmyelinated axons
-large axons transmit impulses at a faster rate because there is less resistance impulse transmission
-myelinated axons use saltatory conduction (jumping) making then faster than unmyelinated axons which use continuous conduction (stepwise)
Depolarization Phase
-entry of sodium ions
-makes membrane potential less negative
Repolarization Phase
-sodium channels close
-potassium channels open
-potassium efflux
-down toward negative membrane potential
Absolute Refractory Period
-depolarization phase
-sodium channel open
-another AP cannot be generated
Relative Refractory Period
-repolarization phase
-sodium channels closed
-an exceptionally strong stimulus can cause sodium channels to open for sodium influx leading to depolarization and generation of another AP
Mutlipolar Neuron
1 axon - 2+ dendrites
-most abundant in human body
Bipolar Neuron
1 axon - 1 dendrite
1 short process from cell body, bifurcates into a central and peripheral process
Motor Neuron
-transmits impulses away from CNS to effector organs
Sensory Neuron
-transmits impulses from sensory receptors TOWARD CNS
Association Neuron
-in CNS between sensory and motor neurons
-99% of neurons in body
Group A Nerve Fibers
-largest diameter
-heavily myelinated
-150 m/s
Group B Nerve Fibers
-intermediate diameter
-lightly myelinated
- 15 m/s
Group C Nerve Fibers
-smallest diameter
- 1 m/s
Autonomic Nervous System
-involuntary muscles
-Parasympathetic: increase energy expenditures
-Sympathetic: conserve energy expenditures
Somatic Nervous System
-voluntary muscles
Dilation of Pupils
-activation of sympathetic nervous system using dilator pupillae muscle
Constriction of Pupils
-activation of parasympathetic nervous system using sphincter pupillae muscle