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Organization, Nerve Impulse, Reflex

Central Nervous System (CNS)

brain and spinal cord

Peripheral Nervous System (PNS)

nerves that extend from brain and spinal cord

spinal nerves

carry impulses to and from spinal cord

cranial nerves

carry impulses to and from brain

sensory (afferent) neurons

carry impulses to CNS (integration center)

motor (efferent) neurons

carry impulses away from CNS to organs (effector)

sensory receptor

responds to stimulus

somatic nervous system

voluntary control (skeletal muscles)

autonomic nervous system

involuntary control (smooth and cardiac muscles)


provides neurons with nutrients


cleans up debris in and around neuron

ependymal cells

keeps cerebrospinal fluid moving & cushions CNS


produces myelin sheath in CNS

satellite cells

protects and cushions cell bodies in PNS

Schwann Cells

forms myelin sheath in PNS

Nissl substance

rough ER


maintain shape of cell body


carries impulses TO cell body


carries impulses AWAY from cell body

axon terminals

storage of neurotransmitters

synaptic cleft

gap between neurons

nodes of Ranvier

gaps between Schwann cells

cutaneous sense organs

sense receptors for pain, temperature, pressure (in the skin)


sense receptors that detect stretch or tension (in muscles and tendons)


bridge between sensory neuron and motor neuron


plasma membrane of a resting neuron


influx of sodium ions that changes polarity of membrane

action potential (nerve impulse)

transmitted signal; all-or-none response


sodium-potassium pump restores initial concentration of ions

neuron-to-neuron communication

release of neurotransmitter from one neuron to another


rapid, predictable, involuntary response to a stimulus

reflex arcs

reflexes occur over neural pathways that involve both PNS and CNS

somatic reflexes

reflexes that stimulate skeletal muscles

autonomic reflexes

reflexes that stimulate smooth and cardiac muscles

first step of reflex arc

sensory receptor in reflex arc

second step of reflex arc

sensory neuron in reflex arc

third step of reflex arc

integration center in reflex arc

fourth step of reflex arc

motor neuron in reflex arc

fifth step of reflex arc

effector organ in reflex arc

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