Central Nervous System Flashcards
(91 cards)
1
Q
Central Nervous System
A
Brain and Spinal Cord
1
Q
Peripheral Nervous System
A
Sensory Nerves and Effector Nerves
2
Q
Sensory Nerves =
A
Afferent or incoming
3
Q
Effector Nerves
A
Motor, Efferent or outgoing
4
Q
Effectors Nerves 2
A
Autonomic and Somatic
5
Q
Autonomic
A
involuntary, to viscera
6
Q
Somatic
A
voluntary, to skeletal muscles
7
Q
Nerve Impulse
A
Neuron responds to stimuli
8
Q
Nerve Impulse then
A
Neurons convert those messages to an electrical signal called
9
Q
Neuron
A
basic structural unit of the nervous system
10
Q
Neuron has three major regions
A
cell body (soma), dendrites, axon
11
Q
Cell body 1
A
contains nucleus
12
Q
Cell body 2
A
cell processes radiate out
13
Q
Dendrites 1
A
receiver cell processes
14
Q
Dendrites 2
A
carry impulse toward cell body
15
Q
Axon 1
A
sender cell process
16
Q
Axon 2
A
starts at axon hillock
17
Q
Axon 3
A
end branches
18
Q
Axon 4
A
axon terminals
19
Q
Electrical signal for communication between
A
periphery and brain
20
Q
Electrical signal must be generated by
A
a stimulus
21
Q
Electrical signal must be propagated down
A
an axon
22
Q
Electrical signal must be transmitted
A
to next cell in line
23
Q
Resting Membrane Potential
A
difference in electrical charges between outside and inside of cell
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Inside more negative relative to outside:
-70 mV
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Cause: uneven separation of charge ions
High [Na+] outside cell
Medium [K+] inside cell
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When charges across membrane differ
membrane is polarized
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RMP maintained in way 1
membrane more permeable to K+ will move to less concentrated areas, outside the cell
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RMP maintained in way 2
actively transports (requires ATP) three Na+ out of cell and two K+ into cell
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RMP maintain result:
more + ions outside of the cell than inside
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RMP maintain result*:
maintenance of -70mV RMP
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Depolarization
occurs when inside of cell becomes less negative (ex: -70mV --> 0 mV)
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Depolarization 2
more Na+ channels open, Na+ enters cell (influx)
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Depolarization 3
required for nerve impulse to arise and travel
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Hyperpolarization
occurs when inside of cell becomes more negative, even below -70 mV (ex: -70 mV --> 90 mv)
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Hyperpolarization 2
more K+ channels open, K+ leaves cell (efflux)
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Hyperpolarization 3
makes it more difficult for nerve impulse to arise
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Depolarization and Hyperpolarization contribute to nervous system function via
Graded potentials (GPs)
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Graded potentials (GPs):
localized changes in membrane potential
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Graded potentials 2
generated by incoming signals from dendrites
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Graded potentials 3
help cell body decide whether to pass signal on
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Graded potentials 4
can excite or inhibit a neuron
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Excitatory Postsynaptic Potential (EPSP)
Na+ channels open = Na+ influx, depolarization
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Inhibitory Postsynaptic Potential (IPSP)
K+ channels open = K+ efflux, hyper polarization
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Strong EPSP will lead to an
Action Potential (AP)
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Action Potential 1
rapid depolarization of neuron's membrane
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Action Potential 2
last 1 ms
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Action Potential 3
AP will be propagated down axon & transmitted to next cell
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How strong must an action potential be?
must reach a threshold mV
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If GP reaches, -55 mV to -50 mV (threshold mV)
AP will occur
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Threshold mV not reached, then no AP
All-or-none principle
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Axon Hillock
keeps total of EPSPs & IPSPs
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-70 to -55 mV
depolarizing GP, Na+ influx
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-55 to +30 mV
depolarizing AP, Na+ influx
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+30 to -70 mV:
depolarizing AP, K+ efflux
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Resting membrane potential
painted by sodium-potassium pumps
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Depolarization, Na+ channels open
Na+ moves into the cell, depolarizing it
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Repolarization, K+
moves out of the cell
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Action Potentials
Propagation Down Axon
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Propagation Speed
are determined 2 characteristics
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Axon Diameter
larger axon = faster
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Myelin 1:
fatty sheath around axon (formed by Schwann Cells)
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Myelin 2:
not continuous (spaces are nodes of Rainier)
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Myelin 3:
speeds up propagation
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Myelin 4:
multiple sclerosis: degeneration of myelin; loss of coordination
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For neurons to communicate
APs transfer from a presynaptic to postsynaptic neuron
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Site of neuron-to-neuron communication
synapse (AP must travel across synapse)
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Presynaptic axon terminal
synapse
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Synapse
Postsynaptic Dendrites
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Postsynaptic Dendrites 1
signal changes form across synapse
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Postsynaptic Dendrites 2
electrical - chemical - electrical
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AP can move
in only one direction
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Synapse
Transmitting APs
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Axon terminals contain
neurotransmitters
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Axon terminals are
chemical messengers
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Axon terminals can
carry electrical AP signal across synaptic cleft
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Axon terminals have the ability to
bind to receptor on postsynaptic surface
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Axon terminals
stimulate GPs in postsynaptic neuron
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If depolarization reaches threshold
an AP occurs, process continues
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Neuromuscular Junction
A Specialize Synapse
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site of neuron-to-muscle communication
uses acetylcholine (ACh) as its neurotransmitter
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Site of neuron-to-muscle communication
passes AP from neuron to muscle cell
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Postsynaptic Cell
muscle fiber
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ACh binds to
receptor at special site: motor end plate
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Depolarizes muscle cell membrane
AP continues on muscle cell
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How many Nuerotransmitters are out there
50+ are known or suspected
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Neurotransmitters can fall into two major categories
small-molecule, rapid-acting & large-molecule (neuropeptides), slow-acting
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ACh and norepinephrine (NE)
govern exercise
88
ACh
stimules skeletal muscle contraction
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then ACh
mediates parasympathetic nervous system effects
90
NE mediates
sympathetic nervous system effects
