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Chapter 11 (ptII)
(Ch.11) Nervous System part 2
54
Anatomy
Undergraduate 2
10/22/2013

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Term
interneurons
Definition
(association neurons)
integration between motor and sensory neurons
nerve impulses travel from one area of CNS to another area of CNS
axon, cell body and dendrites all in CNS
Term
synapse
Definition
point of close proximity between two neurons and neuron and effector cell
Term
chemical and electrical
Definition
two types of synapses
Term
axon
dendrite
Definition
____ of one neuron forms synapse with _____ or cell body of another neuron
Term
presynaptic neuron
Definition
neuron carrying nerve impulse toward synapse
Term
postsynaptic neuron
Definition
neuron carrying nerve impulse away from synapse
receives info at the synapse
Term
postsynaptic cell
Definition
effector cell receives impulse at synapse
Term
electrical synapse
Definition
connected by gap junctions
transmission is rapid
less common
synchronizes activity of groups of cells
location: cardiac and smooth muscle, embryonic neurons, few regions of adult brain
Term
gap junctions
Definition
connect cytosol of adjacent neurons
allows ions and small molecules to pass from one neuron to next
Term
chemical synapse
Definition
neurons do not touch
Neurotransmitter must diffuse across space between presynaptic neuron and postsynaptic neuron cell
Term
synaptic cleft
Definition
fluid filled space separating axon terminal of presynaptic neuron from:
-PM of postsynaptic neuron(cell body or dendrite)
-PM of postsynaptic cell (effector)
prevents electrical signals from passing directly from neuron to neuron
Term
resting membrane potential
Definition
electrical difference across the plasma membrane of a resting neuron
measured in voltage
maintained by the sodium-potassium pump
Term
anions and cations
Definition
energy difference in RMP is due to separation of _____ and _____
Term
neurons and muscle cells
Definition
only ___ and ____ alter their membrane potential as a result of stimulation
Term
potential (stored)
Definition
separation of oppositely charged molecules is a form of ______ energy
Term
-70 mV
Definition
average for resting potential
Term
active transport
Definition
in RMP, carrier protein transports ions against concentration gradient using ATP. This is known as ____ ____.
Term
Na
K
Definition
In RMP:
____ diffuses into cell, while _____ diffuses out of cell through LEAKAGE channels in plasma membrane
Term
graded and action
Definition
two types of signals produced by change in membrane potential
Term
graded potentials
Definition
incoming signals
travel short distances
Term
action potentials
Definition
outgoing signals
travel long distances
Term
depolarization
Definition
inside of plasma membrane becomes less negative than RMP
cell is less polarized
(-70mV)-->(-35mV)-->(0 mV)-->(30mV)
Term
hyperpolarization
Definition
inside of plasma membrane becomes more negative than RMP
cell is more polarized
(-70mV)--> (-90mV)
Term
repolarization
Definition
inside of plasma membrane returns to RMP
internal negativity or polarization is restored
(30mV)-->(0mV)-->(-35mV)-->(-70mV)
Term
graded potentials
Definition
short-lived, localized changes in membrane potential
depolarization or hyperpolarization that occurs on dendrite or cell body of neuron
decreases in magnitude with distance
magnitude varies with strength of distance
Term
voltage
Definition
stronger the stimulus, the more ____ channels, and the farther the graded potential travels
Term
Na
(sodium)
Definition
degree of polarization is determined by amount of ___ entering cell
Term
depolarization
Definition
greater the ______, the farther the graded potential can travel before dying out
Term
graded potentials
Definition
triggered by a change in the neuron environment-->stimulus
Term
depolarization
Definition
(in graded potentials)
Na enters the cell, moving down concentration gradient
Term
refractory period
Definition
time during which a THRESHOLD STIMULUS can NOT produce an action potential
Na+ channels are closed and will NOT open despite strength of stimulus
RMP is being restored
Ensures 2nd AP will not occur before 1st has finished
Term
saltatory conduction
Definition
movement of AP is much faster in myelinated axons
myelin sheath prevents contact with ECF
only Nodes of Ranvier are exposed to ECF
Voltage-gated Na+ channels are concentrated at Nodes
AP generated only at nodes and jump from node to node
Term
myelin sheath
Definition
movement is fast in this
Term
ECF
Definition
myelin sheath prevents contact with ______
Term
Nodes of Ranvier
Definition
only this is exposed to the ECF
Term
threshold stimulus
Definition
refractory period is time in which the ______ _____ can NOT produce an action potential
Term
nerve impulse
Definition
what is an action potential that occurs on an axon?
Term
increased Ca^2+
Definition
what causes synaptic vesicles to fuse with axon terminal plasma membrane
(occurs at synaptic cleft)
Term
exocytosis
Definition
Neurotransmitter is released into synaptic cleft via ______
Term
protein receptors
Definition
Neurotransmitter diffuses across synaptic cleft and binds to ____ _____ on plasma membrane of postsynaptic neuron/cell
Term
excitatory postsynaptic potential
inhibitory postsynaptic potential
Definition
two types of postsynaptic potentials (GPs)
Term
dendrites or cell body
Definition
GPs is depolarization or hyperpolarization that occurs on ____ or _____ of the neuron
Term
initial stimulus
Definition
cat: GP
ion channels only open at site of _____ ______
Term
action potentials
Definition
occur at maximum levels or not at all
Term
summation
Definition
a single EPSP is not strong enough to generate an action potential so it must ____ to generate ATP
Term
temporal summation
Definition
one or more presynaptic neurons must release NT in rapid succession.
first NT produces small EPSP
before EPSP dissipates, more NT is released
Term
spacial summation
Definition
postsynaptic neuron stimulated by NT released from many axon terminals at same time
Term
acetylcholine
Definition
NTs that are:
inhibitory or excitatory
released by all neurons that stimulate skeletal muscle
released by some neurons of ANS
Term
norepinephrine
and epinephrine
Definition
NTs that are:
excitatory or inhibitory
released in both CNS and PNS
Term
divergent
convergent
Definition
two types of neural circuits
Term
divergent
Definition
neuronal circuit:
one neuron stimulates increasing numbers of neurons (amplifying)
Term
convergent
Definition
neuronal circuit:
results in either strong stimulation or inhibition
Term
neurotransmitter mimic
Definition
molecule binds to receptor protein in place of NT and excites or inhibits postsynaptic neuron
mimics effects of NT (many illegal drugs)
Term
neurotransmitter block
Definition
molecule binds to receptor protein in place of NT but results in No effect (many poisons)
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