nervous system chapter 11

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50 Terms

1
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CNS is composed of what?

Brain and spinal chord

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what are the three functions of the nervous system

sensory input, intergration, motor input

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nerve cells travel fastest in:

large myelinated fibers

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central nervous system contains what

Brain and spinal cord. Intergration and command center

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peripheral nervous system does/contains what

paired spinal and cranial nerves. carries messages to and from the spinal cord and brain

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what are the two PNS functional divisions

sensory (afferent) sensory afferent fibers carry impulses from skin, skeletal muscles, and joints to the brain.

Motor (efferent) transmits impulses from the CNS to effector organs

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what are the two motor division parts

somatic nervous sytem: conscious control of skeletal muscles , somatic motor efferent fibers

autonomic nervous system: visceral (autonomic) motor efferent fibers. regulates smooth muscle, cardiac muscle and glands. divisions are sympathetic and parasympathetic

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what are the two principal cell types of the nervous system

neurons- excitable cells that transmit electrical signals

supporting cells- cells that surround and wrap neurons

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what do supporting cells (neuroglia cells) do

provide a supportive scaffolding for neurons, segregate and insulate neurons, guide young neurons to the proper connections, promote health and growth.

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how many supporting cells are in CNS and PNS

four in CNS: astrocytes, microglia, ependymal, oligodendrocytes

two in pns: schwann cells, satalite cells

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Describe astrocytes

most abundant, versatile, and highly branched glial cells.

help form blood brain barriers

guide young neurons

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describe microglia cells

small, ovoid cells with spiny processes. phagocytes that monitor the health of neurons

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describe ependymal

range in shape from squamous to columnar. they line the central cavities of the brain and spinal column( blood brain barrier)

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describe oligodendrocytes

branched cells that wrap CNS nerve fibers (myelinate)

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describe Schwann cells

surround fibers of the PNS (myelinate)

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Describe satellite cells

surround neuron cell bodies with ganglia

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describe neurons (nerve cells)

structural units of the nervous system. composed of a body, axon, and dendrites

their plasma membrane functions in: electrical signaling, and cell-to-cell signaling during development

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describe a nerve cell body

contains the nucleus and a nucleolus

has no centrioles

has well developed Nissl bodies

contains axon hillock- cone shaped area from which axons arise

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clusters of neuron cell bodies are called what

nuclei in the CNS

Ganglia in the PNS

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what are processes

armlike extensions from the soma

called tracts in the CNS and nerves in the PNS

there are two types: axons and dendrites

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describe dendrites of motor neurons

short, tapering, and diffusely branched processes

they are receptive, or input, regions of the neuron- carry info to the soma

electrical signals are conveyed as graded potentials

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describe “axons” structure

slender process of uniform diameter arising from the hillock

long axons are called nerve fibers

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describe axon functions

generate and transmit action potentials (conducting component)

secrete neurotransmitters from the axonal terminals at the end of terminal branches

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movement along axons occur in what two ways

anterograde- toward axonal termanal

retrograde- away from axonal terminal (recycling)

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describe a myelin sheath

whitish, fatty, segmented sheath around most long axons

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what are myelin sheath functions

protect axons

electrically insulate fibers from one another

increase speed of the nerve impulse transmission

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what is ‘‘white'‘ and “gray” matter in the regions of the brain and spinal cord

white matter- dense collections of myelinated fibers

gray matter- mostly soma and unmyellinated fibers

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what are the three neuron classifications (structural)

multipolar- three or more processes, most common major type of CNS

bipolar- two process (axon and dendrite)

unipolar- single process, sensory in PNS

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unipolar neurons are more accurately called

pseudounipolar

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what are the three “functional” neuron classifications

sensory (afferent)- transmit impulses toward the CNS

motor (efferent)- carry impulses away from the CNS

interneurons (association neurons)- shuttle signals through CNS pathways

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neurons are highly irritable -True/False

True

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action potentials, or nerve impulses are:

electrical impulses carried along the length of axons

the underlying functional feature of the nervous system

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nerve fibers are classified according to:

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describe a synapse

a junction that mediates information transfer from one neuron:

-to another neuron

-to an effector

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types of synapses

axodendritic- synapses between the axon of one neuron and the dendrite of another

axosomatic- synapses between

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describe electrical synapses

are less common than chemical synapses

correspond to gap junctions found in other cell types

are important in the CNS- arousal from sleep, mental attention

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describe chemical synapses

specialized for the release of reception of neurotransmitters

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chemical synapses are composed of what two parts

axonal terminal of the presynaptic neuron

receptor region on the dendrites or soma of the postsynaptic neuron

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describe a synaptic cleft

fluid filled space seperating the presynaptic and postsynaptic neurons

prevent nerve impulses from directly passing from one neuron to the next

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one role of the astrocyte is to:

help form the blood brain barrier

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what lines the ventricles in the brain

astrocytes

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oligodendrocytes are only found in :

CNS

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interneurons are only found in:

CNS

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the visceral motor division is further divided into:

sympathetic and parasympathetic divisions

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satellite cells are only found in:

PNS

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a bipolar neuron has:

one axon and one dendrite arising from the soma

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the majority of neurons are

multipolar

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which cells form the myelin sheath in the CNS

oligodendrocytes

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what is the neurolemma

the outermost layer of a schwann cell

50
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which structures are found only in the PNS

nerves