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66 Cards in this Set
- Front
- Back
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control of the body's billions of cells is accomplished by two body-wide communication systems:
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nervous system and endocrine system
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how does the nervous system transmits info?
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very rapidly by nerve impulses conducted from one body area to another
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the communication systems of the body:
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are also its control and integrating systems
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what is homeostasis?
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the balanced and controlled internal environment of the body that is basic to life itself
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what are the organs of the nervous system?
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brain, spinal cord, nerves, specialized sense organs, microscopic sense organs
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what are the two principal divisions of the nervous system?
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central nervous system and peripheral nervous system
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the _____ and _____ _____ make up the central nervous system
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brain , spinal cord
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the usual designation for the nerves of the body is the _____ _____ _____ or ____
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peripheral nervous system, PNS
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_____ is appropriate because nerves extend to outlying or _____ parts of the body
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peripheral, peripheral
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outlying =
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peripheral
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subdivision of the peripheral nervous system:
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autonomic nervous system (ANS)
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autonomic nervous system:
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consists of structures that regulate the body's automatic or involuntary functions
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automatic/involuntary functions:
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heart rate, contractions of stomach and intestines, secretion of chemical compounds by glands
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what are the two types of cells found in the nervous system?
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neurons and glia
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neurons:
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nerve cells
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glia:
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specialized connective tissue cells
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what cells conduct impulses?
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neurons
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what cells support neurons?
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glia
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neurons consist of three parts:
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cell body, dendrites, axon
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what is the cell body?
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main part of neuron
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what are dendrites?
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one or more branching projections of the neuron
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what are axons?
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elongated projection of neuron
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dendrites:
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processes or projections that transmit impulses TO the neuron cell bodies
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axons:
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processes that transmit impulses AWAY from the neuron cell bodies
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axons
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a = away
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there are three types of neurons:
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sensory, motor, interneurons
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_____ neurons transmit impulses ___ the spinal cord and brain from all parts of the body
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sensory, to
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sensory neurons are also called ______ neurons
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afferent
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_____ neurons transmit impulses ____ from the brain and spinal cord
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motor, away
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motor neurons are also called _____ neurons
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efferent
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motor neurons transmit in the _____ direction of sensory neurons
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opposite
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motor neurons do not conduct impulses to all parts of the body - only to two kinds of tissue:
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muscle and glandular epithelial tissue
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interneurons:
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conduct impulses from sensory neurons to motor neurons
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interneurons are sometimes called _____ or _____ neurons
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central, connecting
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myelin:
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white, fatty substance formed by Schwann cells that wrap around some axons outside the cns
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nodes of ranvier:
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indentations between adjacent schwann cells
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neurilemma:
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outer cell membrane of a schwann cell
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axons in the brain and spinal cord:
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have no neurilemma
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potential for regeneration in the brain and spinal cord is
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far less than it is in the peripheral nervous system
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glia (neuroglia)
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do not specialize in transmitting impulses
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glia are
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special types of supporting cells
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glia is a greek word meaning
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glue
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one function of glia cells is to
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hold the functioning neurons together and protect them
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glioma
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one of the most common types of brain tumor that develops from glia
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glia
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regulate neuron function
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some glia are
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relatively large cells that look somewhat like stars because of the threadlike extensions that jut out from their surfaces
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astrocytes:
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glia that look like stars.
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what does astrocyte mean?
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star cells
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the branches of astrocytes
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attach to neurons and to small blood vessels, holding the structures close to each other
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astrocytes:
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form a two-layer structure called the blood-brain barrier (BBB)
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blood brain barrier (BBB)
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separates the blood tissue and nervous tissue to protect vital brain tissue from harmful chemicals that might be in the blood
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microglia
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smaller than astrocytes
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microglia usually remain stationary, but in inflamed or degenerating brain tissue
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they move about, and act as microbe-eating scavengers
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microglia use:
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phagocytosis
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oligodendrocytes
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help hold nerve fibers together
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an important function of microglia is:
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they produce the fatty myelin sheath that envelops nerve fibers located in the brain and spinal cord
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schwann cells
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are glial cells that also form myelin sheaths but do so only in the pns
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a nerve
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is a group of peripheral nerve fibers (axons) bundled together like the strands of a cable
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peripheral nerve fibers:
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usually have a myelin sheath
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peripheral nerves often look white because:
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myelin is white
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tracts are:
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bundles of axons in the cns
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tracts are myelinated:
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and thus form the white matter of the brain and cord
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brain and cord tissue composed of cell bodies and unmyelinated axons and dendrites is called gray matter
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because of its characteristic gray appearance
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endoneurium
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thin wrapping of fibrous connective tissue that surrounds the axons in a nerve
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fascicles:
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groups of endoneurium wrapped axons
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perineurium:
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thin and fibrous, surrounds each fascicle
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