PSYC 1010 Chapter Notes - Chapter 3: Peripheral Nervous System, Efferent Nerve Fiber, Afferent Nerve Fiber

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5 Feb 2013

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Chapter 3
September 22, 11
Nervous system- signals are always being transmitted, received
and integrates. It handles the information of my body. It is tissue
that is made ip of cells.
2 cells:
1. Neurons individual cells in the nervous system that
receive, integrate and transmit information
make communication within the nervous system and
also may send messages from the nervous system to
soma/ cell body has nucleus and the chemical machinery
odendrites- are branches of the neuron. They receive all the
information which then go into the soma.
oAxon- after the information has gone in through the
dentrites to the soma it then leaves the soma to go to
other neurons, glans or muscles.
Can branch off to communicate with other cells.
Myelin speeds up the transmission of signlas that
move along axons.
oTerminal buttons- this is where the axon ends and it
secretes chemicals called neurotransmitters. These
chemicals are messangers that activate near neurons.
oSynapses- when neurons exchange information with each
Summary: info is received at dendrites. Then passted through
soma and alon the axon, which is then transmitted to dendrites
of other cells at the synapses.
2. Glia are around the nervous system and give support
for neurons.
Give nourishment, remove waste for neurons and
give insulation for neurons to axons.
oMyelin sheaths are from glia cells.
oPlay a role in development of nervous system
in the embryo.
oCan signal to other glia cells
Neural impulse- electrochemical reaction. On this inside and
outside it has charged atoms called ions.
oDifference in flow rates results to higher
concentraton of negative ions inside the cell.
oThis voltage means that the neuron is a store
of potential energy.
oResting potentioal neuron is stable, negative
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charge when the cell isn’t active.
Constant voltage of neuron- cell is quiet.
When its stimulated- channels in cell membrane open
allowing positively charged sodium ions to come in.
Action potential shift in neurons electrical charge that
travels along an axon.
Voltage change goes down the axon
Absolute refractory its after action potential and hits is
when the cell membrane is closed up and its “resting” only for a
very short amount of time.
After this is the relative refractory period the neuron can
fire and this one is very intense.
Neuron either fires or it doesn’t, and action potentials are
all the same size.
Stronger stimulus will get a more rapid volley of neural
Thicker axons transmit impulses more rapidly.
Neural impulse is a signal, which is transmitted from
neurons to other cells.
Synaptic cleft- a gap between neurons. In order for signals
to communicate it has to pass this gap. When the action
potential is at the acons it triggers the release of
neurotransmitters, which are chemical that transmit information
from different neurons.
Chemicals stores in synaptic vesicles.
Vesicle and membrane fuse together- neurotransmitters
are released. They then diffuse across the synaptic cleft of
receiving membrane. And here they can bind with other
molecules in receptor sites.
Postsynaptic potentials range in size which increases or
decreases the probability of neural impulses.
Messaging from cell to cell:
1. Excitatory positive voltage shift that increases the
chances that postsynaptic neuron will fire action
2. Inhibitory does the opposite.
Reuptake- gets synapses to recycle materials.
Neuron has to integrate all the messages it sends and receives
before it desides to send a neural impulse. If the right amount of
PSPs happen the electrical currents add up which causes the
cells voltage to reach the threshold and finally the action
potential can be fired.
oIf too many inhibitory PSPs happn it will not allow
excitatory PSPs.
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