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82 terms

Nervous System 2012

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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
integration
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
neuroglia
glial cells; supporting cells in the nervous system
astrocytes
star-shaped supporting cells in the CNS that are the most abundant & versitile; assists in exchanges between blood in capillaries and neurons
microglia
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
oligodendrocytes
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
neuron
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
process
armlike extension from the cell body
dendrites
short, tapering branching extensions of motor neurons that serve as receptive or input regions; transmit the nerve impulse towards the cell body
axon
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)
interneurons
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
depolarization
the process during the action potential when sodium is rushing into the cell causing the interior to become more positive
repolarization
outflow of positive ions from the nerve cell restores the electrical conditions at the membrane to the polarized, or resting state
hyperpolarization
when axon is repolarizing, more K+ ions leave the cell, causing the cell to become MORE polarized than before it started
threshold
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
synapse
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.
neurotransmitter
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)
acetylcholine
a neurotransmitter that enables learning and memory and also triggers muscle contraction
dopamine
neurotransmitter that influences voluntary movement, attention, alertness; lack of dopamine linked with Parkinson's disease; too much is linked with schizophrenia
acetylcholine
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?
peripheral
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?
oligodendrocytes
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?
chemical
What type of message crosses a synapse between two neurons?
peripheral
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?
acetylcholine
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?
False
True or False--The brain never recieves the message in a reflex response.
False
True or False--Bigger axons take longer to conduct impulses.
False
True or False--Electrical nerve stimulation is a more effective anesthesia than chemical inhibitors.
False
True or False--Neurons are mitotic and therefore are responsible for most brain neoplasms.
False
True or False--Ependymal cells show irritability and conductivity.
True
True or False--Nerve cells have a semi-permeable plasma membrane.
False
True or False--Astrocytes line the central cavities of the brain.
True
True or False--The intensity of light does not change the rate of the pupilary response.
microglia
What cells are phagocytic and clear away debris from dead cells?
astrocytes
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