Ch 3 Definitions: Neurophysiology: The Structure & Function of the Cells of the Nervous System Flashcards
gliay
cells in the nervous system
that support
the activities of neurons
neuron
a cell of the nervous system
that is specialized for
information processing and communication
macroglia
large glial cells,
including
astrocytes, ependymal cells, oligodendrocytes, and Schwann cells
microglia
tiny, mobile glial cells
that migrate to areas of damage
and digest debris
astrocyte
a large, star-shaped glial cell of the CNS
responsible for structural support, isolation of synapse, control of the extracellular chemical environment at the synapse, and possibly communication
ependymal cells
glial cells
lining the ventricles and central canal
of the spinal cord
oligodendrocyte
a glial cell
that forms the myelin
on CNS axons
Schwann cell
a glial cell
that forms the myelin
on axons in the PNS
synapse
the junction
between two neurons
at which information is transferred from one to another
blood-brain barrier
an impediment to the transfer of molecules
from the circulation into the brain
formed by the astrocytes
exosome
tiny vesicle that removes debris
and transports material
organelle
a small structure within the cell
that carries out a specific function
cell body/soma
the main mass of a neuron,
containing the nucleus and many organelles
axon
the branch of a neuron
usually responsible for
carrying signals to other neurons
dendrite
the branch of a neuron
that generally receives information
from other neurons
intracellular fluid
the fluid inside the cell;
AKA cytoplasm
extracellular fluid
the fluid surrounding the cell;
AKA interstitial fluid
permeability
a property of a substance
that determines the extent to which
other substances may pass through it
ion channel
a protein structure
embedded in a cell membrane
that allows ions to pass
without the use of additional energy
ion pump
a protein structure
embedded in a cell membrane
that uses energy
to move ions across the membrane
ions
an electrically charged particle
in solution
voltage-dependent channel
an ion channel that opens or closes
in response to
the local electrical environment
ligand-gated channel
an ion channel
in the neural membrane
that responds to chemical messengers
sodium-potassium pump
an ion pump
that uses energy
to transfer 3 Na+ TO the extracellular fluid
for every 2 K+ ions retrieved FROM the extracellular fluid
calcium pump
a protein structure
embedded in the neural membrane
that uses energy
to move Ca+ out of the cell
cytoskeleton
a network of filaments
that provides the internal structure of a neuron
microtubule
the largest type of fiber in the cell cytoskeleton
responsible for transport
of neurochemicals and other products
to and from the cell body
anterograde transport
movement of materials
from the cell body of a neuron
to the axon terminal
along the microtubules
retrograde transport
movement of material
from the axon terminal
back to the cell body
via the cell’s system of microtubules
neurofilament
a neural fiber found in the cell cytoskeleton
responsible for structural support
microfilament
the smallest fiber found in the cell cytoskeleton
that may participate in the changing of the length and shape
of axons and dendrites
nucleus
substructure within cell
contains cell’s DNA
nucleolus
substructure within nucleus
where ribosomes are produced
ribosome
organelle in cell body
involved with protein synthesis
endoplasmic reticulum
organelle in cell body
participates in protein synthesis
Golgi apparatus
organelle in cell body
packages proteins in vesicles
mitochondria
organelles that provide energy to the cell
by transforming pyruvic acid and oxygen
into molecules of adenosine triphosphate (ATP)
neurochemical
a small organic molecule
that participates in neural activity
synaptic gap
the tiny fluid-filled space
between neurons at a synapse
dendritic spine
a knob on the dendrite
that provides additional membrane area
for the formation of
synapses with other neurons
axon hillock
the cone-shaped segment of axon
located at the junction of the axon and cell body
that is specialized for
the generation of axon potentials
action potential
the nerve impulse arising in an axon
initial segment
the portion of axon
between the axon hillock
and the first segment of myelin
myelin
the fatty insulating material covering some axons
that boosts the speed and efficiency of electrical signaling
local circuit neuron
a neuron that communicates
with neurons in its immediate vicinity
projection neuron
a neuron with a very long axon
that communicates with neurons
in distant areas of the nervous system
collateral
one of the branches near the end of the axon
closest to its targets
axon terminal
the swelling at the tip of an axon collateral
specialized for the release of neurochemicals
axonal varicosity
a swelling in an unmyelinated segment of axon
containing mitochondria
and, in some cases, synaptic vesicles
synaptic vesicles
a small structure in the axon terminal
that contains neurochemicals
node of Ranvier
the uncovered section of axon membrane
between 2 adjacent segments of myelin
unipolar neuron
a neuron with 1 branch that extends a short distance from the cell body & then splits into 2 branches
bipolar neuron
a neuron with 2 branches extending from the cell body, 1 axon & 1 dendrite
multipolar neuron
a neuron that has multiple branches extending from the cell body, usually 1 axon & numerous dendrites
sensory neuron
a specialized neuron that translates incoming sensory information into electrical signals
motor neuron
a specialized neuron that communicates with muscles & glands
interneuron
a neuron that serves as a bridge between sensory & motor neurons
resting potential
the measurement of the electrical charge across the neural membrane with the cell is not processing information
depolarization
a change in a membrane potential in a more positive direction
threshold
the level of depolarization at which an action potential is initiated
hyperpolarization
a change in membrane potential in a more negative direction
absolute refractory period
the period in which an action potential will not occur in a particular location of an axon regardless of input
relative refractory period
the period following an action potential in which larger than normal input will produce a second action potential but in which normal input will be insufficient
saltatory conduction
the movement of an action potential from node of Ranvier to node of Ranvier, down the length of the myelinated axon
gap junction
a type of synapse in which a neuron directly affects an adjacent neuron through the movement of ions one cell to the other
chemical synapse
a type of synapse in which messages are transmitted from one neuron to another by neurochemicals
excitation
a neural message that increases the likelihood that a receiving cell will produce an action potential
inhibition
a neural message that decreases the likelihood that a receiving cell will produce an action potential
wiring transmission
process in which chemicals diffuse from one cell to impact an adjacent cell or cells through private, highly localized channels
volume transmission
process in which neurochemicals diffuse through the extracellular fluid & CSF to influence cells located some distance away from the releasing cell
exocytosis
the process in which vesicles fuse with the membrane of the axon terminal & release neurochemicals into the synaptic gap
autoreceptor
receptor site located on the presynaptic neuron that provides information about the cell’s own activity levels
receptors
a special protein structure embedded in a neural membrane that responds to chemical messengers
recognition molecules
a molecule within a receptor that binds to specific neurochemicals
ionotropic receptor
a receptor protein in the postsynaptic membrane in which the recognition site is located on the same structure as the ion channel
metabotropic receptor
a protein structure embedded in the postsynaptic membrane containing a recognition site & a G protein
- neurochemicals binding to these receptors do not directly open ion channels
G protein
a protein found on the intracellular side of a metabotropic receptor that separates in response to the binding of a neurochemical & travels to adjacent areas of the cell to affect ion channels or second messengers
second messenger
a chemical within the postsynaptic neuron that is indirectly activated by synaptic activity & interacts with intracellular enzymes or receptors
reuptake
a process for ending the action of neurochemicals in the synaptic gap in which the presynaptic membrane recaptures the molecules of neurochemical
transporter
a receptor in the presynaptic membrane that recaptures released molecules of neurochemical in the process of reuptake
excitatory postsynaptic potential (EPSP)
a small depolarization produced in the postsynaptic cell as a result of input from the presynaptic cell
graded potentials
an electrical signal that can vary in size & shape
inhibitory postsynaptic potential (IPSP)
a small hyperpolarization produced in the postsynaptic cell as a result of input from the presynaptic cell
neural integration
the determination of whether to fire an action potential, based on the summation of inputs to a neuron
spatial summation
neural integration in which the combined inputs from many synapses converge on the axon hillock, where an action potential will result if threshold is reached
temporal summation
neural integration in which excitation from one active synapse is sufficient to initiate the formation of an action potential
axo-axonic synapse
a synapse in which both the presynaptic & postsynaptic elements are axons
presynaptic facilitation
at a synapse between 2 axons, the increase of neurochemical release by the postsynaptic axon as a result of input from the presynaptic axon
presynaptic inhibition
at a synapse between 2 axons, the decrease of neurochemical release by the postsynaptic axon as a result of input from the presynaptic axon
