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central nervous system

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central nervous system

brain and spinal cord

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peripheral nervous system

nerves

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sensory nerves (afferent)

impulses are sent to the CNS; detect changes inside and outside of the body

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integration

within CNS; processing incoming sensory input decision making

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motor

impulse sent from CNS to effectors to cause response

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neurons

nerve cells; conduct impulses

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neuroglia

surrounds nerve cells; do not conduct impulses

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parts of a neuron

cell body, dendrites, axon

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cell body

cytoplasm, mitochondria, lysosomes, microtubules, golgi apparatus, nucleus

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nissl bodies

chromatophilic substance that consists mainly of rough er

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dendrites

receive input; highly branched. provide many receptors; can be 1 or more

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axon

transmits input; carries the input away from the cell body; usually one long fiber

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impulses travel

dendrite-> cell body-> axon

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multipolar

1 axon and MANY dendrites

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bipolar

1 axon and 1 dendrite

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unipolar

1 process which splits into 2 branches, the peripheral and central processs

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sensory neurons (afferent)

carry impulses from peripheral body parts to CNS

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interneurons

lie within the CNS and form links with other neurons

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motor neurons (efferent)

carry impulses from CNS to peripheral body parts

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neuroglial cells in PNS

schwann and satellite

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neuroglial cells in CNS

astrocytes; oligodendrocytes; microglia; ependyma

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schwann cell

produce myelin on myelinated neurons

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how do schwann cells wrap around

tightly wrap around fibers, forming a myelin sheath; just neurilemma with no myelin sheath

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satellite cell

clusters of neuron cell bodies called ganglia

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myelinated fiber

fiber that has a myelin sheath; impulse travels faster

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unmyelinated fiber

fiber that does not have a myelin sheath; impulse travels slower

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gray matter

nervous tissue containing lots of cell bodies and unmyelinated fibers

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white matter

nervous tissue containing lots of myelinated fibers

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astrocyte

large star shaped cells between neurons and blood vessels; structural support, communication, and transportation between blood vessels and neurons

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oligodendrocytes

shaped like astrocytes with fewer processes, occur in rows along axons; form myelin sheath in the CNS ( NO neurilemma)

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microglia

small cells with few processes found throughout CNS; structural support and phagocytosis

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ependyma

cuboidal and columnar cells in the brain and spinal cord that line the cavities; help with diffusion

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regeneration in CNS

no regeneration; no endoneurial tube and no neurilemma

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regeneration in PNS

might occur; bc the endoneurium's presence may prevent scar tissue from coming in before the process can regrow

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synapse

junction between axon of one neuron and dendrite or cell body of another neuron

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presynaptic fiber

neuron which sends impulse to synapse; releases neurotransmitters into synaptic cleft

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postsynaptic fiber

neuron which has receptors for the neurotransmitters

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first step in synaptic transmission

Presynaptic knob of axon contains vesicles filled with neurotransmitters.

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second step in synaptic transmission

When impulse reaches knob, Ca++ diffuses into cytoplasm.

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third step in synaptic transmission

Vesicles move to membrane and release neurotransmitters into cleft.

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fourth step in synaptic transmission

Neurotransmitters cross cleft and bind to receptors on postsynaptic membrane of neuron (either dendrite or cell body)

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fifth step in synaptic transmission

If enough neurotransmitters are present, an action potential will occur.

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sixth step in synaptic transmission

Neurotransmitters are either decomposed or they move back into presynaptic knob.

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neuron potential

the concentration of ions on either side of the membrane affects its charge distribution

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changes in potentials

when a stimulus encounters a neuron, it responds by changing its permeability to various ions, which affects the potentional

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hyperpolarized

the resting membrane becomes more negative

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depolarized

the resting membrane becomes more positive

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nerve impulse

if stimulus is strong enough it cause Na gates to open Na flows into cell, depolarizing membrane action potential is reached at +30 mV K+gates open K+ moves out, repolarizing membrane hyperpolarizes for brief moment active transport pumps Na out and K in

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resting potential

The charge distribution when a nerve is at rest. No impulse being conducted, so membrane is not very permeable to POTASSIUM (K+) and even less permeable to SODIUM (Na+). Active transport has to be used to pump K+ in and Na+ out. More negatively charged ions on the inside of the cell so more positive particles are going to move in (attraction): More Na+ on outside, K+ on inside Membrane is positive on the outside, negative on the inside Membrane is said to be polarized -70mV- is the difference in charges (resting potential)

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action potential

the rapid sequence of Na and K movements

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nerve impulse

chain reaction of action potentials

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all-or-none response

if a neuron responds at all, it responds COMPLETELY or conducts COMPLETELY or not at all

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refractory period

a short time period after a nerve impulse where a stimulus will not conduct the neuron

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saltatory conduction

type of impulse conduction along myelinated fibers

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nerve impulse speed

thick faster than thin myelinated faster than unmyelinated

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excitatory postsynaptic potential

neurotransmitter triggers Na+ gates to open and membrane is depolarized (more likely reach action potential)

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inhibitory postsynaptic potential

neurotransmitter triggers K+ gates to open and membrane is hyperpolarized (less likely to reach action potential)

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facilitation

if a neuron receives a net excitatory stimulation, but is subthreshold it is more susceptible to an action potential the next time

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monoamines

modifications of amino acids

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epinephrine

boost of energy

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dopamine

feel good hormone

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serotonin

mood stabilizer

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amino acids

unmodified amino acids

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glycine

inhibitory neurons in brain and spinal cord

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gamma-aminobutyric acid (GABA)

inhibitory neurons in brain and spinal cord

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peptides

short chains of amino acids

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substance P

pain perception

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endorphins

reduces pain

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convergence

when a neuron receives impulses from 2 or more other neurons allows the brain to receive info from different regions of the body and respond in a special way

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divergence

when 1 neuron sends impulses to 2 or more other neurons-results in an amplified response

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sensory fibers

contains only sensory fibers (afferent)

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motor fibers

contains only motor fibers (efferent)

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mixed fibers

contains both sensory and motor fibers

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general somatic efferent fibers

carry impulses from CNS to skeletal muscles

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general visceral efferent fibers

carry impulses from CNS to smooth muscles and glands

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general somatic afferent fibers

carry impulses from skeletal muscles and skin to CNS

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general visceral afferent fibers

carry impulses from smooth muscles and glands to CNS

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reflex arc

simple impulse pathway during a reflex

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receptor

specialized nerve endings stimulated by change

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effector

smooth muscle or gland that responds

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meninges

found beneath the bone and soft tissues of nervous system; brain and skull, spinal cord and vertebral column protect the brain and spinal cord

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3 layers outer to inner

dura mater arachnoid mater pia mater

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meningitis

inflammation of the meninges

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spinal cord

31 segments ends between 1 and 2 lumbar relays impulses and info between body and CNS

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