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Unformatted text preview: @maozmimarmmwaznbas 220% UM©GD§ W§F§G§i $881,133
$5 83’ WW ' CN: Use liqht colors tor A. B. and C. mm the upper drawing. each at the syn—
.apses shown has two parts Color onty the ones labeled wrth subscripts (A. B. C).
Color the nerve impulse title (D) and the related directional arrows (2)Color the
numbered steps in the lower drawing. Note the change at color in the presynaptic
membrane between exocytosrs (H) and endocytosis (K). BASiC
@(3 SYt-‘JAPS‘BS m AMU@A
° "A Connections between and among neurons are called synapses.
They are. tor the most part. non-contact. chemical transmissions
between one part ot a neuron and another There are other less
common types ot synapses (some ot which are not shown) as
well. For example, we show a complex at synapses between three
axons and a dendrite, all surrounded by a neuroglial sheath (glom-
erulus). Synapses permit the conduction of electrochemical im-
pulses among a myriad ot neurons almost instantly. tn the simplest
example, a monosynaptic retlex arc between a sensory neuron and
a motor neuron requrres one synapse At the other extreme. there
.ire polysynaptic pathways in the brain and spinal cord involvrng
millions 0t synapses Certain neurons are known to receive more
than 5000 synapses . , . each! Multiple synapses greatly increase
the available options ol nervous activrty. The ability to integrate.
coordinate. associate. and modify sensory input and memory to
achieve a desued motor command is directly related to the num—
ber 0t synapses involved in the pathway W 3 * TYPES OF smApses
mesmeeme miss?) me E @83@@W@§0§H
69©QF§WEDFD© meme: J _
@@@§C®'ﬁ’@@ei 30 @&D@O@K aggmgrgggﬁo g? enter axon termrnal Axon
membrane Here we present a typical axo-dendntic synapses The axon ( t) is
presynaptrc (in lront ot the synapse). Within the cytoplasm ot the
axon terminal are synaptic vesicles (2) transporting molecules of
neurotransmitter. These vesrcles migrate toward and fuse with the
presynaptic membrane (:3). Neurotransmitter is spilled into the tiny
synaptic clelt by a process at exocytosrs. The neurotransmitter
molecules interact with the receptors on the postsynaptic mem-
brane ot the postsynaptic dendrite (4) tnactivated neurotransmitter
Iragments are taken up by the presynaptic membrane (5; endo—
cytosrs). enclosed in a synaptic vesrcte. and re-synthesized (6). The neurotransmitter may enhance (facilitate) or depress (inhibit)
the electrical activity of the postsynaptic membrane. Sutticiently
owned by multiple lacuitory synapses, the postsynaptic neuron witl
depoiarize and transmit an impulse to the next neuron or ettector.
sufficiently inhibited by multiple inhibitory synapses, the postsynap-
tic neuron Will not be depolarized and WI" not transmit an impulse. All at this occurs very rapidly and globally throughout the nervous
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This note was uploaded on 01/02/2012 for the course PSY 301 taught by Professor Edwardjones during the Fall '10 term at N.C. State.
- Fall '10