YAP, Benito Nino R

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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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