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nervous system

the master control and communication system of the body

sensory input

the gathered information of the changes inside and outside the body; stimuli


a process in which the nervous system interprets the sensory input and decides what should be done at each moment

motor output

the response of the nervous system to integration by activating effector organs (muscle/glands)

central nervous system (CNS)

the integrating and command center of the nervous system; consists of the brain and spinal cord

peripheral nervous system (PNS)

the communication lines that link all parts of the body to the CNS; consists of cranial and spinal nerves

sensory (afferent) division

the subdivision of the PNS that consists of nerve fibers that convey impulses TO the CNS from sensory receptors

motor (efferent) division

the subdivision of the PNS that consists of nerve fibers that transmit impulses FROM the CNS to effector organs (muscles and glands)

somatic nervous system

voluntary nervous system; the subdivision of the motor division that is composed of somatic motor nerve fibers that conduct impulses from the CNS to skeletal muscles

autonomic nervous system

the subdivision of the motor division that consists of visceral motor nerve fibers that regulate the activity of smooth muscles, cardiac muscles and glands

sympathetic division

the division of the ANS that activates the body to cope with some stressor (danger, excitement etc); the fight, fright, and flight subdivision

parasympathetic division

the division of the ANS that oversees digestion, elimination, and glandular function; the resting and digesting subdivision; feed and breed subdivision


glial cells; supporting cells in the nervous system


star-shaped supporting cells in the CNS that are the most abundant & versitile; assists in exchanges between blood in capillaries and neurons


small ovoid-shaped supporting cells in CNS that have long thorny processes; can transform into macrophages to destroy bacteria, viruses, and damaged cells

ependymal cells

supporting cells in the CNS that line the cavities of the brain/spinal cord


supporting cells in the CNS that wrap their cytoplasmic extensions around the nerve fibers, producing insulating covering called myelin sheaths

satellite cells

supporting cells in the PNS that surround neuron cell bodies within ganglia; function still unkown

Schwann cells

the suppporting cells in PNS that surround and form myelin sheaths around larger nerve fibers in the PNS


the structural units of the nervous system; also called nerve cells

cell body

soma; contains cell organelles and carries on cell functions of synthesis and metabolis


armlike extension from the cell body


short, tapering branching extensions of motor neurons that serve as receptive or input regions; transmit the nerve impulse towards the cell body


a process that carries nerve impulses away from the nerve cell body

axon hillock

a cone-shaped area of the cell body from which the nerve impulse is triggered to move down the nerve fiber

myelin sheath

whitish, fatty, segmented sheath that protects and electically insulates fibers form one another and increases the speed of nerve transmission

myelinated fibers

axons with a myelin sheath that conduct nerve impulses rapidly

unmyelinated fibers

axon with myelin that conduct nerve impulses slowly

nodes of Ranvier

that gaps between adjacent Schwann cells along an axon

white matter

regions of the brain and spinal cord containing dense collection of myelinated fibers

gray matter

regions of the brain and spinal cord containing mostly nerve cell bodies and unmyelinated fibers

multipolar neuron

neuron with many dendrites extending from the cell body and only one axon

bipolar neuron

neuron with two processes extend for the cell; one is the dendrite, the other is an axon

unipolar neuron

neuron with one process that extends from the body, an axon

sensory neuron

afferent neruon; transmits impulses from sensory receptors in the skin or internal organs toward or into the central nervous system

motor neuron

efferent neuron; carry impulses away from the central nervous system to the effector organs (muscles or glands)


association neurons; lie between motor and sensory neurons in neural pathways and shuttle signals through CNS pathways where integration occurs

action potential

nerve impulse

resting membrane potential

the difference in electrical charges on either side of a cell membrane when the cell is at rest, measured in millivolts, inside membrane is more negative than outside, difference in change is ions moving- K+ diffusing out of cell


the process during the action potential when sodium is rushing into the cell causing the interior to become more positive


outflow of positive ions from the nerve cell restores the electrical conditions at the membrane to the polarized, or resting state


when axon is repolarizing, more K+ ions leave the cell, causing the cell to become MORE polarized than before it started


the level of stimulation required to trigger a neural impulse; -55 mV

All or None Principle

the law that the neuron either generates an action potential when the stimulation reaches threshold or it doesn't fire when stimulation is below threshold

reflex arc

pathway for a simple nervous reaction: knee jerk, sensory receptor, sensory neuron, motor neuron, and effector that are involved in a quick response to a stimulus


the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or cleft.


a chemical messenger that travels across the synapse from one neuron to the next and influences whether a neuron will generate an action potential(impulse)


a neurotransmitter that enables learning and memory and also triggers muscle contraction


neurotransmitter that influences voluntary movement, attention, alertness; lack of dopamine linked with Parkinson's disease; too much is linked with schizophrenia


an excitatory neurotransmitter secreted by motor neurons innervating skeletal muscle

receptor, efferent neuron, integration center, afferent neuron, effector

What is the path of a simple spinal reflex?


Sensory receptors are part of which division of the nervous system?

refractory period

What is the period after an initial stimulus when a neuron is not sensitive to another stimulus?

sympathetic and parasympathetic

The autonomic nervous system is divided into what subdivisions?


Schwann cells are functionally similar to what?

sensory, interneuron, motor

What neuron pathway is involved in a reflex arch?

dendrites, axon, soma

What are the primary components of a nerve cell?


What type of message crosses a synapse between two neurons?


The voluntary and non-voluntary divisions are part of which branch of the nervous system

action potential

What is the electrical wave that travels down a nerve cell axon?

Action potentials are moving too slowly to communicate

Why is nerve function impaired when myelin surrounding an axon is damaged?


What is the most common neurotransmitter in the body?

central nervous system

Which branch of the nervous system contains the major organs of the nervous system?

peripheral nervous system

Which branch of the nervous system connects the brain and spinal cord to other organs?

the spinal cord

What is the primary integration center of a spinal reflex?

nerve cell bodies and glial cell bodies

What is the gray matter of the central nervous system composed of?


True or False--The brain never recieves the message in a reflex response.


True or False--Bigger axons take longer to conduct impulses.


True or False--Electrical nerve stimulation is a more effective anesthesia than chemical inhibitors.


True or False--Neurons are mitotic and therefore are responsible for most brain neoplasms.


True or False--Ependymal cells show irritability and conductivity.


True or False--Nerve cells have a semi-permeable plasma membrane.


True or False--Astrocytes line the central cavities of the brain.


True or False--The intensity of light does not change the rate of the pupilary response.


What cells are phagocytic and clear away debris from dead cells?


What cells support and brace neurons and control the chemical environment?

ependymal cells

What cells may be ciliated and line the cavities of the brain?

oligodendrocytes in CNS and Schwann cells in PNS

What cells produce the myelin sheath?

conditioned reflex

What reflex is conscious, voluntary and learned?

simple reflex

What reflex is involuntary, rapid and unconscious?

Peripheral Nervous System

The following are characteristics of which branch of the nervous system? carries messages to and from the brain and spinal cord, contain somatic and autonomic divisions, contain motor and sensory nerve cells.

Central Nervous System

The following are characteristics of which branch of the nervous system? the brain and spinal cord, integration, command center

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