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35 Cards in this Set

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