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54 Cards in this Set

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  • Back
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which part of the embryo are both neurons and glial cells derived?
neuroepithelium
what is another word for cell processes in neurons?
neurites
what is the name for the RER found in neurons?
Nissl substances
why is lipofuscin often found in neurons?
because they are long-lived and do not regenerate
what is the point on the axon where action potentials are generated?
axon hillock
what is the term for branching of axons?
terminal arborization
what characterizes the cytoplasm of axons?
lack of Nissl substance and presence of elaborate cytoskeletal array
which two microtubule-associated proteins are primarily responsible for transport of proteins up and down axons?
dynein (toward soma) and kinesin (toward axon terminal)
None
what is the name for a synapse between an axon and a dendrite? Between an axon and a cell body?
axodendritic synapse; axosomatic synapse
which organelles are abundant in the axon terminal?
mitrochondria, SER, endosomes
why does the presynaptic membrane of the axon bouton appear to be thickened when viewed with an EM?
due to presence of many specialized proteins involved in docking and release of synaptic vesicles.
None
the depolarization of nerve cells in action potentials is largely due to which ion channels?
voltage-gated Na+ channels
which phenomenon prevents the action potential from doubling back on itself in the axon?
absolute refractory period
depolarization of the axon terminal leads to influx of which ion?
Calcium
to what do neurotransmitters bind once released into the synaptic cleft?
specific receptors on the post-synaptic membrane
receptors in post-synaptic membrane have which 2 functions?
ion channels or enzymatic action
which, ion channels or enzymatic receptors, have second messenger mechanisms which create a prolonged effect?
enzymatic receptors
are ion channels in post-synaptic membranes normally excitatory or inhibitory?
either, depending on which ions are allowed through
what is the term which refers to a transmitter that either binds to the ligand-gated ion channel and affects its ease of opening or that works through the second messenger system?
neuromodulator
what are the 3 ways by which neurotransmitters are deactivated?
1) enzymatic breakdown, 2) diffusion, 3) reuptake into the presynaotic nerve terminal
does the activity of a neurotransmitter depend more on the identity of the NT or the receptor?
receptor
myelination of axons is performed by which cells in the PNS? In the CNS?
Schwann cells; oligodendrocytes
how do Schwann cells recognize axons?
via glycoproteins on Schwann cells and axons
how is the cytoplasm in Schwann cells attenuated in wrapping around axons?
via hydrogen bonding on inner surface of Schwann cell membranes
None
what is the name for the regions of Schwann cells where cytoplasm has not been completely attenuated?
Schmidt-Lanterman clefts
how do nutrients and ions cross the many layers of myelin?
via gap junctions
what is the term used for the gaps between adjacent Schwann cells? What is concentrated in these gaps?
Nodes of Ranvier; ion channels
what is the name for the conduction of action potentials down an axon, from one Node of Ranvier to another?
saltatory conduction
if the internodal distance on axons is increased, does the speed of conduction increase or decrease?
increase
what is the name of the connective tissue that covers the individual axons? Fasicles? Entire nerve?
endoneurium; perineurium, epineurium
why do peripheral nerves have a wavy appearance in cross-sections?
so they can stretch without breaking
what is the name for the cells which surround ganglia? What is their function?
satellite cells; to maintain the proper environment around the ganglion cells
what is the name of the simplest peripheral sensory nerve ending? What do they normally detect?
free nerve endings; pain or temperature
None
which specialized sensory nerve ending winds around certain specialized connective tissue cells that distribute force to the nerve fiber?
Meissner's corpuscles
which specialized sensory nerve ending has layers of connective tissue circumferentially arranged around a nerve ending? What do these detect?
Pacinian corpuscle; deep pressure and vibration
how many axons are there per muscle fiber?
1
what is the primary function of glial cells?
to support and protect the neurons of the CNS
what are the two main categories of glial cells?
microglia and macroglia
from what do macroglia arise? Microglia?
neural epithelium via glioblasts; monocytes
what important function do astrocytes perform in neurons?
maintain the interstitial environment, including proper levels of ions within the nervous system.
which macroglial cell is responsible for metabolizing neurotransmitters and manufacturing growth factors for support of neurons?
astrocytes
which macroglial cells touch the surface of the brain underneath the pia mater?
astrocytes
which macroglial cells contact all blood vessels within the brain via foot processes that induce the formation of an epithelium that is highly specialized? What is the name for this epithelium with many tight junctions and few pinocytotic vesicles?
astrocytes; blood-brain barrier
what is the major difference in function between Schwann cells and oligodendrocytes?
oligodendrocytes have many processes and each one myelinates several axons whereas Schwann cells myelinate one axon per cell
are the proteins in Schwann cells and oligodendrocytes identical?
no, some disease differentially target Schwann cells or oligodendrocytes
which type of cells line the ventricles and central canal of the spinal cord?
ependymal cells
in the certain areas of the ventricles, which cells have tight junctions and do not allow substances from fenestrated capillaries to pass easily into cerebrospinal fluid? What is the name for these regions? For the barrier?
ependymal cells; choroid plexus; blood-CSF barrier
which of the glial cells are phagocytotic?
microglia
from which germ cell layer do microglia arise?
mesoderm
what is the name for an axon branch that does not occur near the axon terminal?
collateral branch
what is the name of the intermediate filaments that compose the structural support for the axons?
neurofilaments
Schwann cells are derived from which part of the embryo?
neural crest cells
what is the name for the part of the Schwann cell that myelinates the axon?
neurolemma
what is the name for the structure in the ventricular system which produces CSF?
choroid plexus