Chap 14 Flashcards Preview

Human Anatomy Exam 3 > Chap 14 > Flashcards

Flashcards in Chap 14 Deck (42):
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Nervous system

all nervous tissue in the body

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central nervous system

brain and spinal cord

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peripheral nervous system

cranial nerves, spinal nerves, and ganglia

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Functionally divided:

sensory and motor nervous systems

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sensory nervous system

conveys sensory information to the CNS

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motor nervous system

conducts motor commands to the muscles and glands

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neuron characteristics

excitable
transmit nerve impulses
non mitotic

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glial cells

completley surround and support neurons

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generally neurons have:

a cell body, dendrites and an axon

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classified structurally as

unipolar, bipolar, or multipolar depending on the number of attachments to the cell body.

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classified functionally as

sensory, motor or interneurons

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CNS glial cells:

astrocytes, ependymal cells, microglial cells, and oligodendrocytes

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astrocytes

help form the blood brain barrier and regulate tissue fluid composition

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ependymal cells

line CNS cavities and produce cerebrospinal fluid

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microglial cells

act as phagocytes in nervous tissue

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oligodendrocytes

mylinate CNS axons

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PNS glial cells

satellite cells and nerolemmocytes

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satellite cells

support neurons cell bodies in ganglia

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nerolemmocytes

mylinate PNS axons

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Nerve impulse:

a rapid movement of a charge along a neurons plasma membrane

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Mylination

oligodendrocytes (CNS) and nerolemmocytes (PNS) form a discontinuous mylin sheath along the axon, with small gaps (neurofibril nodes)

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neurofibril nodes

small gaps between mylin sheath help conduct impulses faster

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unmylinated axons

associated with a neurolemmocyte but not ensheathed by it.

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Wallerian degeneration

regeneration of damaged neurons
*limited to PNS axons that are able to regrow under certain conditions*

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Epineurium

surrouds fascicles

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perineurium

surrounds individual fasicles

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endoneurium

surrounds individual axons

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synapse

a specialized junction between two excitable cells where a nerve impulse is transmitted

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synaptic knobs

swellings of axons at their end branches

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synaptic cleft

space between the presynaptic and postsynaptic cells

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classification of synapses

axodendritic, axosomatic or axoaxonic

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axodendritic

most common: presynaptic knobs synapse with postsynaptic dendrites (standard delivery)

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axosomatic

between synaptic knobs and the cell body of postsynaptic neuron (express delivery)

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axoaxonic

least common: presynaptic knob with postsynaptic knob (first class delivery)
*usually overides brains orders

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electrical synapses

a flow of ions pass from presynaptic cell to postsynaptic cell through gap junctions

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chemical synapses

nerve impulse causes a release of a chemical neurotransmitter from presynaptic cell that induces response in the postsynaptic cell.

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what increases rate of conduction?

presence of a myelin sheath, larger the axon diameter.

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neuronal pools

groups of interneurons- cordinate and integrate nervous activity.

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converging circuit

neurons synapse at a single postsynaptic neuron
>----

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diverging circuit

spreads information to several neurons
-----<

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reverberating circuit

neurons continue to restimulate presynaptic neurons in the circuit.
-0

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Parallel after discharge circuit

involves parallel pathways that process the same information over different amounts of time and deliver that information to the same output cell.
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