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It is the basic information processing
units of the nervous system.
It is specialized for
action potential conduction
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It has 3 main components
a. Cell body- located in the CNS
b. Dendrites- extensions that carry nerveimpulses toward the cell body
Myelin- increases the velocity of nerve impulses
c. Axons- carry nerve impulses away from
the cell body
Axon hillock where nerve impulse begin
There are 3 types of neurons
1.Sensory carries impulses from
peripheral sensory receptors to the CNS
3. Associational(interneurons)- tra
nsmit
impulses from neuron to neuron
2.Motor- transmit impulses awayfrom the CNS to an effector
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IF the stimulus is
strong enough anaction potential/ nerve
impulse is generated
1. The action potential arrives at
the synaptic end bulb of a
presynaptic neuron2. It opens the voltage-gated Ca
channels
3. in Ca causes exocytosisof synaptic vesicles releasing
neurotransmitters
4. Neurotransmitters bind to
receptors in the post synaptic
neuron
5. Binding opens ion channels,
allowing certain ions to flow
across the membrane
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the membranepotential changes
As ions flow
through
Depending on the ions, the
change in membrane potentialmay be
EXCITATION generation of another nerve impulse
INHIBITION - cessation of the nerve impulse
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EXCITATORY NEUROTRANSMITTERS
Include: DOPAMINE AND NOREPINEPHRINE
INHIBITORY NEUROTRANSMITTERS
Include: GABA(gamma Aminobutyric acid) AND GLYCINE
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Without an action potential, there
would be no muscular contraction.
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The muscle contains many elongated and cylindrical cells
called muscle fibers
Each muscle fiber is covered by a plasma membrane
called the sarcolemma.
The sarcoplasm contains many mitochondria that
produce ATP and stores Ca for muscular
contraction
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Extending along the muscle fibers are cylindrical structures called myofibrils
Each myofibril consists ofthickandthin filaments
The filaments overlap and form sarcomeres the basic functional
units of striated muscle fibers.
The thick filaments contain
The thin filaments consist of
Myosin
Actin, troponin and troposmyosin
Each plays a vital role inMUSCULAR
CONTRACTION
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Amuscle action
potentialmust be
generated.
FIRST!!!
similar with
synaptic
transmission
When the action
potential reaches the
neuromuscular junction
It opens Ca channels
causing Ca to bind to
troponin in the thin
filament
Exposing theMYOSIN-BINDING
SITES
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1. Myosin heads
hydrolyze ATP and
become reoriented and
energized 2.Myosin heads
bind to actinforming cross
bridges3.Myosin
crossbridges rotate
toward center of the
sarcomere
(power stroke)
4. As myosin head
weakens it eventually
detaches
It then bindsagainwith ATP
For as long as ATP and Ca are
available !!!
And the CYCLE
continues.....
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