Nervous System Flashcards
sensory input
gathered information from stimuli
integration
processing and interpreting sensory input
motor output
active response to stimuli
CNS
brain and spinal cord
PNS
outside CNS
functional subdivisions of PNS
sensory (afferent)
motor (efferent)
sensory
to CNS
motor
from CNS
somatic NS
from CNS to muscles
autonomic NS
from CNS to smooth muscle, cardiac muscle, and glands
neuron parts
cell body
axon
dendrite
soma
cell body
neurofibrils
extend into fibers for support
nissl bodies
rough ER with ribosomes
dendrite
branched, receptive surface
axon
slender, cylindrical, smooth with uniform diameter conducts away from cell body
collaterals
branches of axon
telodendria
fine extensions of axon which terminate close to other receptive surfaces
axonal transport
impulses that cause biochemical production
Schwann cells
PNS only; neuroglia sheaths surrounding axons
myelin
tightly wound membranes composed of lipoprotein
neurilemma sheath
surrounds myelin sheath containing the nuclease and most of the cytoplasm
nodes of Ranvier
gaps between myelin sheaths in Schwann cells
white matter
groups of myelinated fibers
gray matter
groups of unmyelinated fibers
unipolar
single nerve fiber that branches into axon and dendrite
bipolar
two nerve fibers, one axon, one dendrite
multipolar
one axon, many dendrites
sensory neurons
carry impulses to CNS; unipolar or bipolar
interneurons
within CNS, multipolar; built-in filter
motor neurons
carry impulses from CNS; multipolar
neuroglia
provide scaffolding
CNS neuroglia
astrocytes, oligodendrocytes, microglia, ependyma
PNS neuroglia
Schwann cells
astrocytes
star shaped, between neurons and blood vessels; provide support and hold structures together; blood brain barrier; metabolism of glucose, K+ concentration
oligodendrocytes
from myelin within CNS; numerous cellular processes; one may provide myelin for many axons
microglia
phagocyte
ependyma
cuboidal or columnar in shape with cilia; inner lining producing CSF
resting potential
inside cell is negative, outside is positive; -70mV
potential difference
difference between 2 points
hyperpolarization
more negative than normal
depolarization
more positive
graded potential
nerve impulses that increase in frequency
threshold potential
point at which active potential is activated; -55mV
summation
additive effect of all dendrite stimulation
action potential
threshold potential reached; sodium rushes in and causes depolarization; +30mV
nerve impulse
wave of action potentials moving down the membrane
refractory period
threshold stimulus will not trigger another impulse after the initial one
absolute refractory period
change in sodium permeability and cannot be stimulated
relative refractory period
reestablishment of resting potential, strong enough impulse may trigger response
saltatory conduction
nerve impulses traveling along myelinated fibers jumping the nodes of Ranvier; faster than unmyelinated fiber
all or none phenomenon
impulse either triggers response or doesn’t; impulses all carry same strength, but my vary in frequency.
calcium ion function
close sodium channels during action potential; deficiency causes continuous impulse transmission.
potassium ion function
increase in extracellular, action potential easily reached; decrease in extracellular, action potentials hard to reach
anesthetic drugs
decrease sodium membrane permeability
synapse
nerve impulse passageway from neuron to neuron
synaptic cleft
presynaptic and post synaptic neurons around the synapse gap
synaptic transmission
process in which impulse in presynaptic neuron signals postsynaptic neuron
synaptic knobs
located in axons at presynaptic terminals; impulses trigger neurotransmitter release from synaptic vesicles
chemical synapse transfer
- calcium gates open in presynaptic axon terminal; impulse triggers depolarization opening calcium and sodium channels releasing calcium into the terminal
- neurotransmitter is released by by exocytosis into synaptic cleft due to calcium fusing to axonal membrane
- neurotransmitter binds reversibly to protein receptors on postsynaptic membrane
- postsynaptic neuron excited or inhibited depending on type of receptor neurotransmitter binds to
synaptic delay
rate-limiting step of neural transmission
acetylcholine
first identified; released at neuromuscular junctions; released, binds briefly, then released and degraded
biogenic amines
catecholamines and indolamines; behavior and emotional regulation
catecholamines
dopamine, norepinephrine, epinephrine
indolamines
serotonin, histamine
amino acids
gamma-aminobutyric acid (GABA), glycine, aspartate, glutamate; only in CNS
peptides
neuropeptides like substance P mediate pain signals; endorphins and enkephalins act as natural opiates or euphorias
neuronal pools
groups of neurons within CNS
convergence
fibers originating from different parts of the NS leadings to the same neuron
divergence
impulse originating from a single neuron in the CNS bay be amplified so enough can reach motor units