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Microanatomy
Nervous Tissue
41
Medical
Professional
09/07/2008

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Term
Function of neuron
Definition
communication
Term
Function of glial cell
Definition
support
Term
Central Nervous System
Definition
brain, spinal cord, optic nerve, and retina
Term
Peripheral nervous system
Definition
nerves projecting from brain and spinal cord, periphera ganglia, communicating nerves between peripheral ganglia
Term
autonomic nervous system
Definition
1. part f PNS
2. composed of sympathetic and autosympathic
Term
# neurons in brain
Definition
10^12
Term
Neurotransmitters
Definition
chemical signals passed between neurons at synapses
Term
neuron characteristics
Definition
1. each neuron is unique
2. numerous processes extending from cell body
3. dendrites carry impulses toward body
4. axons carry impulses away from body
Term
Cell Biology of Neurons
Definition
1. have a cell body (soma, perikaryon)
2. nucleus, RER (Nissl substance), prominent Golgi, numerous mitochondria, well developed cytoskeleton, lots of euchromatin and prominent nucleolus
3. axons and dendrites have complex cytoskeleton of neurofilaments (10nm), microtubles, microfilaments
Term
Axon hillock
Definition
pyramidal portion of soma that joins to axon, site where dendritic inputs are summed
Term
Anterograde flow
Definition
1) soma to axon
2) driven by ATPase, microtubule-associated kinesin
3) slowly (~2mm/day; proteins and actin filaments)
4) rapidly (~200mm/day; mitochondria, vesicles)
Term
Retrograde flow
Definition
1) axon to soma
2) driven by ATPase, microtubule-associated protein dynein
3) carries vesicles from axon terminus for reloading of neurotransmitter
Term
Multipolar neuron
Definition
many dendrites and an axon or two
found in motor horn of spinal cord
Term
Bipolar neuron
Definition
one dendrite and one axon
retina
Term
pseudounipolar
Definition
axon and dendrite are essentially the same
neurons in dorsal root ganglia
Term
Spinal cord histology
Definition
1. Central "butterfly" of grey matter
2. surrounded by white matter
3. central canal filled with CSF, lined by ependymal cells
Term
Composition of grey matter
Definition
abundance of neuron cell bodies, some myelin, and glia
Term
Composition of white matter
Definition
few neuron cell bodies, lots of myelin and glia
Term
Composition of dorsal horn of spinal cord
Definition
sensory neurons receiving sensory input from neurons with cell bodies in dorsal root ganglia and dendrites on end organs
Term
Composition of ventral horns
Definition
motor neurons sending out axons to innervate peripheral skeletal muscle
Term
# Glia cells in brain
Definition
10^13
Term
Function of myelin
Definition
1.isolates and insulates neuronal processes
2. produced by glia
Term
Nodes of Ranvier
Definition
-gaps between adjacent schwann cells
-axon only exposed here
-site where cytoplasm of one schwann cell ends and another one begins
-speeds conduction velocity
Term
multiple sclerosis
Definition
de-myelinating disease
Term
oligodendrocyte
Definition
1. myelinates CNS
2. can myelinate different processes of one or multiple neurons
Term
Schwann cell
Definition
1. produce myelin in PNS
2. can only myelinate a single process on indvidual cell
Term
Myelin in PNS
Definition
-produced by schwann cells
-found on exons of motor neurons and dendrites of sensory neurons
-made of schwann cell membrane
-grows by elongation of mesoaxon (sides of schwann cell that wrap around neuron)
Term
Schmidt-Lanterman incisures
Definition
conical defects in myelin
filled with schwann cell cytoplasm to nourish myelin
Term
unmyelinated neuron
Definition
1. slow conduction velocity
2. associated with several schwann cells but not wrapped around
Term
Myelin in CNS
Definition
-foot like processes from oligodendroglia associated with several different neurons
-have nodes of ranvier and multiple layers of myelin
Term
Site of protoplasmic astrocytes
Definition
astrocyte in gray matter
Term
Site of fibrous astrocytes
Definition
astrocyte in white matter
Term
astrocyte
Definition
-glial cell associated with blood vessels and neurons
-multiple foot processes define outer boundaries of epithelium by attaching to BM
Term
blood brain barrier
Definition
-Restricts crossing of substances (drugs) from crossing blood vessel to brain
-tight junctions prevent diffusion
-astrocytes may play a role
Term
Microglia
Definition
-small pleomorphic phagocytes
-immune surveillance of CNS
-bone marrow derivative
-activated when BBB breached
-clean up debris from cell death and injury in CNS
-look flat
Term
mononuclear phagocyte system
Definition
1.monocytes
2. microglia
3. macrophages (kupffer cells)
Term
satellite cells
Definition
-surround neuron cell bodies in ganglia
-functionally isolate and/or support neurons
-present in autonomic ganglia and dorsal root ganglia
Term
Muller cells
Definition
support retinal neurons
Term
Bergmann glia
Definition
provide migratory pathways for developing neurons
Term
ependymal cells
Definition
-cuboidal-columnar cells that line lumen of CNS
-have apical cilia and microvilli
Term
choroid plexus
Definition
specialized tissue that produces CSF
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