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224 Cards in this Set
- Front
- Back
What four things is the nervous system composed of? |
brain, spinal cord, nerves, ganglia
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What are the 3 general functions of the nervous system?
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Collect information
Process and evaluate information Initiate response to information |
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Specialized nervous system cells
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neurons
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_____ are specialized nervous system structures that monitor changes in both the internal and external environment called stimuli
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Receptors
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Changes to the internal and external environment is called _____
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stimuli
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_____ include all three types of muscle tissue and glands.
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Effectors
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What are the different types of effectors controlled by the nervous system?
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All three types of muscle tissue and glands
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What are the two anatomic divisions of the nervous system?
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central nervous system (CNS)
peripheral nervous system (PNS) |
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____ includes the brain and spinal cord
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CNS
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_____ includes nerves and ganglia
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PNS
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_____ are bundles of neuron processes (axons)
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nerves
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____ are clusters of neuron cell bodies located along nerves
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ganglia
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What are the two functional divisions of the nervous system?
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sensory and motor
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_____ is responsible for receiving sensor information FROM receptors that detect stimuli and transmitting this information TO the CNS.
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sensory nervous system
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How is the sensory nervous system subdivided?
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somatic (conscious)
visceral (automatic) |
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Receptors of the somatic sensory nervous system include:
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eyes, nose, tongue, ears, skin, proprioreceptors
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Receptors in muscle and joints that detect body position
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proprioreceptors
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_____ sensory components detect stimuli that we don't consciously perceive
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visceral sensory components
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Receptors of the visceral sensory nervous system include:
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structures located within blood vessels and internal organs, e.g., heart, stomach, kidneys
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What is another name for the motor nervous system?
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efferent nervous system
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The _____ is responsible for initiating and transmitting motor output FROM the CNS TO effectors
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motor nervous system
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This system controls muscle tissue and glands
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motor nervous system
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Is the motor nervous system subdivided into somatic and visceral parts
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yes
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The _____ component initiates and transmits motor output from the CNS to voluntary skeletal muscles
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somatic motor
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what is the other name for autonomic motor nervous system?
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visceral motor
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the visceral motor component of the motor nervous system innervates and regulates:
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cardiac muscle, smooth muscle, and glands
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What are the two subdivisions of the autonomic nervous system?
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sympathetic; parasympathetic
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_____ is the primary tissue of the nervous system.
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Nervous tissue
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nervous tissue is composed of two distinct cell types:
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neurons and glial cells
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_____ are excitable cells that initiate and transmit electrical signals.
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neurons
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_____ cells are nonexcitable cells that primarily support and protect neurons
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glial cells
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Neurons have several special characteristics including:
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excitability
conductivity secretion extreme longevity amitotic |
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This is a responsiveness to stimulation
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excitability
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The type of stimulation that a neuron responds to is dependent upon ______
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its location
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Most neurons usually respond only to binding of secreted molecules called _____
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neurotransmitters
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neurotransmitters are released from
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other neurons
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These are electrical changes that are quickly propagated along the plasma membrane of neurons following stimulation
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conductivity
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Neurons release neurotransmitters in response to _____
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conductive activity
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How many types of neurotransmitters does a typical neuron release?
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only one type
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a neurotransmitter may have either ___ or ___ effect on its target organ
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excitatory or inhibitory
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T/F
most neurons formed during fetal development are still functional in very elderly individuals |
True
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When is mitotic development lost in most neurons?
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during fetal development of neurons
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What are the exceptions to loss of mitotic development of neurons during fetal development?
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olfactory epithelium of the nose and certain areas of the brain
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This region of the brain is involved in memory processing:
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hippocampus
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This region of the brain contains a population of neural stem cells
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hippocampus
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What are the basic structural features of a neuron?
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cell body, dendrites, an axon
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What is another name for a cell body?
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soma
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What is another name for a soma?
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cell body
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a cell body is enclosed by a _____
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plasma membrane
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a cell body has _____ surrounding a nucleus
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cytoplasm
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_____ serve as the neuron's control center
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cell bodies
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_____ conduct electrical signals to the axon
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cell bodies
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electrical signals can either be initiated _____ or _____
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within the cell body;
received from the dendrites |
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What is the cytoplasm within a neuron cell body called?
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perikaryon
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Ribosomes are formed in ___ in a neuron
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nucleolus
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Where is the nucleolus in a neuron?
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The nucleus
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_____ occurs at approx 400 millimeters per day and involves movement along microtubules.
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Fast axonal transport
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_____ occurs at apprix .1 - 3 millimeters per day and results from the flow of the axoplasm, also called axoplasmic flow.
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Slow axonal transport
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______ are the most common type of neuron
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multipolar neurons
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These neurons have many dendrites and a single axon that extends from the cell body.
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Multipolar neurons
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_____ have two processes that extend from the cell body - one dendrite and one axon.
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bipolar neurons
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The location of these neurons is relatively limited in humans eg retina of the eye and olfactory mucosa in the nasal cavity
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bipolar neurons
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In what two locations can bipolar neurons be found in humans?
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retina of the eye, olfactory mucosa in the nasal cavity
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What are the three categories of functional classification of neurons?
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Sensory neurons
Motor neurons Interneurons |
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Are most sensory neurons unipolar, bipolar, multipolar, or anaxonic? What are the exceptions?
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unipolar
retina and nasal mucosa are bipolar |
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All motor neurons are unipolar, bipolar, multipolar, or anaxonic?
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multipolar
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Where do the cell bodies fo the motor neurons lie?
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In the CNS
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What is another name for sensory neurons?
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afferent neurons
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What is another name for afferent neurons?
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sensory neurons
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What is another name for motor neurons?
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efferent neurons
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What is another name for efferent neurons?
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motor neurons
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what is another name for interneurons?
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association neurons
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what is another name for association neurons
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interneurons
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Interneurons lie entirely within the ___
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CNS
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_____ facilitate communication between sensory and motor neurons
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interneurons
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_____ outnumber all other neurons
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interneurons
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it is estimated that ____% of our neurons are _____
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interneurons
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Interneurons are generally multipolar, unipolar, bipolar, anaxonic
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multipolar
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A _____ is a cable-like bundle of parallel axons that are components of the PNS
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nerve
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A nerve is a cable-like bindle of parallel axons that are components of the _____
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PNS
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A thick layer of dense irregular connective tissue that encloses the entire nerve and provides both support and protection.
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Epineurium
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What is the epineurium?
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A thick layer of dense irregular connective tissue that encloses the entire nerve and provides both support and protection
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a layer of dense irregular connective tissue that wraps fascicles, which are bundles of axons. This layer supports blood vessels
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perineurium
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What is the perineurium?
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a layer of dense irregular connective tissue that wraps fascicles, which are bundles of axons. This layer supports blood vessels.
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This layer of connective tissue wrappings supports blood vessels
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perineurium
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An individual axon in a myelinated neuron is surrounded by _____, then wrapped in the _____
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neurolemmocytes; endoneurium
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What kind of connective tissue separates and insulates each axon as part of the endoneurium?
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areolar
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What separates and electrically insulates each axon?
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endoneurium (areolar connective tissue)
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Within which connective tissue layer lie capillaries that supply each axon?
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endoneurium
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_____ nerves extend from the brain
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cranial nerves
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_____ nerves extend from the spinal cord
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spinal nerves
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What are the two structural classifications of nerves?
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cranial nerves and spinal nerves
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What are the three functional classifications of nerves?
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sensory nerves, motor nerves, mixed nerves
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Sensory nerves relay information (to/from) the CNS
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to
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Motor nerves relay information (to/from) the CNS
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from
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What are the three connective tissue wrappings in a nerve, and what specific structure does each ensheathe?
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Epineurium; entire nerve
perineurium; fascicles or bundles of axons endoneurium; each axon |
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The specific location where a neuron is functionally connected to either another neuron or an effector
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synapse
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What is a synapse?
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The specific location where a neuron is functionally connected to either another neuron or an effector
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What are the two types of synapses in the human body?
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chemical; electrical
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Most synapses within the nervous system are _____ synapses (chemical, electrical)
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chemical
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A _____ synapse is composed of a presynaptic neuron, which is a signal producer, and a postsynaptic neuron, which is the signal receiver or target
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chemical synapse
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A chemical synapse is composed of a ______ which is a signal producer and a _____ which is the signal receiver
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presynaptic neuron; postsynaptic neuron
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in regards to a chemical synapse, which is the signal producer and which is the signal receiver or target?
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presynaptic is the producer
postsynaptic is the receiver or target |
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Transmission between a pre and post synaptic neuron occurs when _____ molecules stored in synaptic vesicles are released from the synaptic knob of a presynaptic neuron into the synaptic cleft.
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neurotransmitter molecules
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There is a ______ associated with neurotransmitter release at chemical synapses.
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synaptic delay
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What causes the synaptic delay?
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release of neurotransmitter from presynaptic cell, the diffusion across the synaptic cleft, and the binding to receptors in the postsynaptic plasma membrane.
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An _____ is composed of a presynaptic and postsynaptic neuron fused together
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electrical synapse
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_____ are present in the plasma membranes of both neurons and facilitate the flow of ions between cells in electrical synapses
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gap junctions
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Is there synaptic delay with electrical synapses?
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no
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Which has synaptic delay? Chemical synapses or electrical synapses?
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chemical synapses
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Where are electrical synapses in the body?
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limited regions of the brain and the eyes
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what kind of synapses are in limited regions of the brain and the eyes?
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electrical synapses
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Are glial cells excitable?
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No
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What is the primary function of glial cells?
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to support and protect the neurons
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What is another name for glial cells?
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neuroglia
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Are glial cells found in both the CNS and PNS?
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yes
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what is another name for neuroglia
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glial cells
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Are glial cells larger or smaller than neurons?
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smaller
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Are glial cells capable of mitosis?
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Yes
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Do glial cells transmit nerve signals?
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no
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The _____ cells cooperate to physically protect and help nourish neurons as well as provide an organized, supporting scaffolding for all the nervous tissue.
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glial
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During development, _____ cells form the framework that guides young, migrating neurons to their final destinations.
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glial cells
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Do glial cells outnumber neurons or vice versa
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glial cells outnumber neurons
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_____ account for roughly half of the volume of the nervous system
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glial cells
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Large cel with numerous cell processes; in contact with neurons and capillaries; most common type of glial cell
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Astrocyte
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Helps form the blood-brain barrierRegulates tissue fluid compositionProvides structural support and organization to the CNSAssists with neuronal developmentReplicates to occupy space of dying neurons
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Astrocyte
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Simple cuboidal or columnar epithelial cells that line cavities in brain and spinal cord; cilia on apical surface
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Ependymal cell
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Lines ventricles of brain and central canal of spinal cordAssists in production and circulation of cerebrospinal fluid (CSF)
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Ependymal cell
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Small cell with slender branches from cell body; least common type of glial cell
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Microglial cell
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Defends against infectious agents and engulfs debris from dead or dying neurons
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Microglial cell
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Rounded, bulbous cell with slender cytoplasmic extensions; extensions wrap around CNS axons
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Oligodendrocyte
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Myelinates and insulates CNS axonsAllows faster action potential conduction along axons in the CNS
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Oligodendrocyte
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Flattened cell; groups of these cells cluster around neuronal cell bodies in a ganglion
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Satellite cell
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Protects and regulates nutrient and waste exchange for cell bodies in ganglia
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Satellite cell
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flattened cell wrapped around a portion of an axon in the PNS
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Neurolemmocyte
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Myelinates and insulates PNS axons and allows for faster action potential conduction along an axon in the PNS
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Neurolemmocyte
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What are the four types of glial cells found in the CNS?
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astrocytes, ependymal cells, microglia, and oligodendrocytes
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astrocytes, ependymal cells, microglia, and oligodendrocytes are:
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The four types of glial cells found in the CNS
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These glial cells of the CNS have a star-like shape
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astrocytes
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Astrocyte glial cells of the CNS have projections that touch both _____ and _____
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capillary walls, neurons
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_____ are the most abundant glial cell in the CNS and constitute over 90% of the nervous tissue in some areas of the brain
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Astrocytes
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Astrocytes nurture, protect, support, and guide neurons in these 5 ways:
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help form the blood - brain barrier
regulate tissue fluid composition form a structural network assist neuronal development occupy the space of dying neurons |
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The ends of astrocyte processes are called _____
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perivascular feet
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What are perivascular feet?
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The ends of astrocyte processes
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The _____ and the _____ together contribute to a blood brain barrier (BBB)
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perivascular feet; capillaries
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The _____ strictly controls movement of tubstances from exiting the blood and entering the nervous tissue in the brain
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Blood-brain barrier (BBB)
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How do astrocytes help regulate the chemical composition of the interstitial fluid within the brain ?
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controlling movement of ions and molecules between the blood and the interstitial fluid
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The cytoskeleton in _____ strengthens and organizes nervous tissue in the CNS by forming a framework to support neurons
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astrocytes
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_____ help direct the development of neurons in the fetal brain by secreting chemicals that regulate the formation of connections between neurons
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astrocytes
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When neurons are damaged and die, the space they formerly occupied is often filled by cells produced by ______ _______, a process termed astrocytosis.
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astrocyte division
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The process of astrocyte division is called _____
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astrocytosis
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_____ are ciliated simple cuboidal or simple columnar epithelial cells that line the internal cavities of the brain and spinal cord
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Ependymal cells
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What shapes can ependymal cells be?
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Simple cuboidal or simple columnar
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What forms the choroid plexus?
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ependymal cells and capillaries
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What helps produce cerebral spinal fluid (CNS)?
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choroid plexus
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What is CNF?
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A clear liquid that bathes the external surfaces of the CNS and fills its internal cavities.
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A clear liquid that bathes the external surfaces of the CNS and fills its internal cavities.
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Cerebral spinal fluid
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What is the purpose of the cilia on ependymal cells?
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To help circulate CSF
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What helps circulate CNF?
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The cilia on ependymal cells
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These are typically small cells that have slender branches extending from the main portion of the cell
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Microglia
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This type of glial cell represents the smallest percentage of CNS glial cells
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microglial cells
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This type of glial cell is classified as a phagocytic cell of the the immune system
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Microglial cells
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Microglial cells wander through the CNS and replicate in response to _______
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an infection
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These glial cells in the CNS protect against microorganisms and other potentially harmful substances by engulfing infectious agents and removing debris from dead or damaged nervous tissue
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microglial cells
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How many types of glial cells are found in the PNS?
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Two
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What are the two types of glial cells found in the PNS?
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Satellite cells; neurolemmocytes
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_____ are flattened cells arranged around neuronal cell bodies in a ganglion.
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Satellite cells
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What is a ganglion?
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a collection of neuron cell bodies located outside the CNS
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_____ physically separate cell bodies in a ganglion from their surrounding interstitial fluid
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satellite cells
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_____ regulate the exchange of nutrients and waste products between neurons and their environment in the PNS
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satellite cells
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What is another name for neurolemmocytes?
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Schwan cells
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What is another name for Schwan cells?
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neurolemmocytes
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These flattened cells ensheathe PNS axons to form a myelin sheath
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neurolemmocytes
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These are large cells with a bulbous body and slender cytoplasmic extensions or processes (CNS)
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oligodendrocytes
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The processes of _____ (CNS) ensheathe portions of axons of many different neurons
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oligodendrocytes
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The wrapping around an axon by either an oligodendrocyte or neurolemmocyte
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myelin sheath
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This protective covering around the axon insulates and prevents the passage of ions through the axonal membrane. This allows for faster action potential propagation within the CNS
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myelin sheath
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If a person suffers from meningitis, which type of glial cell usually replicates in response to the infection?
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Microglia
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Which specific type of glial cells ensheaths axons in the PNS?
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Neurolemmocytes
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_____ is the process by which part of an axon is wrapped with myelin.
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Myelination
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_____ is the insulating covering around the axon that consists of repeating concentric layers of plasma membrane of glial cells
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myelin
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Myelination is completed by _____ in the PNS and by _____ in the CNS
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neurolemmocytes; oligodenrocytes
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The high _____ content of the myelin gives an axon a distinct, glossy-white appearance and serves to effectively insulate the axon
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lipid
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The wrapped inner portion of a neurolemmocyte on an axon is called the
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myelin sheath
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The outer-most part of the neurolemmocyte around an axon is made up of _____ and _____ and is called the _____
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cytoplasm, nucleus; neurilemma
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A neurolemmocyte in the PNS can myelinate only a _____ mm portion of an axon
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1
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The gaps between the neurolemmocytes are called _____
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neurofibril nodes
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what is another name for a neurofibril node?
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nodes of Ranvier
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What is another name for nodes of Ranvier?
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neurofibril nodes
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What is the difference between what a neurolemmocyte and an oligodendrocite can myelinate?
|
a neurolemmocyte can only myelinate a 1 mm portion of a PNS axon at a time. an oligodendrocyte can myelinate a 1mm portion of multiple axons of the CNS at a time.
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Is a neurilemma formed with CNS myelination?
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No
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Is a neurilemma formed with PNS myelination?
|
Yes
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Are neurofibril nodes between oligodendrocyte myelin sheaths on an axon?
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Yes
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Are all axons myelinated?
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No
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Are PNS unmyelinated axons associated with the neurolemmocyte?
|
Yes, they rest in a depression within the neurolemmocyte, but no sheathe is wrapped around the axon.
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Are CNS unmyelinated axons associated with oligodendrocytes?
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No
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What is the function of the myelin sheathe?
|
Insulation
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Can a damaged PNS axon regenerate and if so under what conditions?
|
Yes, if the cell body remains intact and a critical amount of neurilemma remains.
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The success of PNS axon regeneration depends upon two primary factors:
|
1 - the amount of damage
2 - the distance between the site of the damaged axon and the structure it innervates the possibility of repair decreases with an increase of either of these two factors. |
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______ play an active role in PNS axon regeneration
|
neurolemmocytes
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The process of axon regeneration (PNS) follows what stages? (5)
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|
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What are some of the reasons regeneration of damaged neurons within the CNS is very limited?
|
1 - oligodendrocytes do not release a nerve growth factor and actively inhibit axon growth by producing and secreting several growth-inhibitory molecules. 2 - the large number of axons crowded within the CNS tends to complicate regrowth activities. 3 - both astrocytes and connective tissue coverings may form some scar tissue that obstructs axon regrowth.
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Neurons contain _____ proteins for moving substances across the plasma membrane
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transport
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_____ move substances up (against) a concentration gradient, a process that requires energy
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Pumps
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Why do pumps require energy?
|
Because they are moving substances against a concentration gradient.
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The plasma membrane of neurons contains both ____ pumps and _____ pumps
|
sodium-potassium (Na+/K+)
calcium (Ca2+) |
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_____ provide the means to move a substance down (with) the concentration gradient
|
channels
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List the major types of channels (3)
|
Leak (passive) channels
Chemically gated channels Voltage-gated channels |
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What is another name for leak channels?
|
passive channels
|
|
What is another name for leak channels?
|
Passive channels
|
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These channels are always open, allowing continuous diffusion of a specific type of ion from a region of high concentration to a region of low concentration.
|
Leak channels
|
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These channels are normally closed and open in response to binding of a neurotransmitter.
|
Chemically gated channels
|
|
These channels are normally closed and open in response to changes in electrical charge (potential) across the plasma membrane
|
Voltage-gated channels
|
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Most voltage-gated channels have one gate that is in one of two states; open or closed. _____ voltage-gated channels are unique because they have two gates.
|
Na+
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What are the two gates of a Na+ voltage-gated channel?
|
activation gate and inactivation gate
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What are the activation gate and inactivation gate?
|
The two gates of Na+ voltage-gated channels
|
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What are the three states of voltage-gated Na+ channels?
|
1 - Resting state
2 - Activation state 3 - Inactivation state |
|
Describe the resting state of the voltage-gated Na+ channels.
|
Although the inactivation gate is open, the activation gate is closed and entry of Na+ is prevented.
|
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Describe the activation state of the voltage-gated Na+ channels.
|
Both the inactivation gate (which remains open) and the activation gate are open (activation gate opens in response to a voltage change); Na+ moves into the cell through the open channel.
|
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Describe the inactivation state of the voltage-gated Na+ channels.
|
Although the activation gate is open, the inactivation gate is TEMPORARILY closed (for several milliseconds) following activation of the Na+ channel - during this time, it cannot be stimulated to reopen, and entry of Na+ is prevented. (The resting state of voltage-gated Na+ channels is reestablished as the inactivation gate opens and the activation closes.)
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What pumps and/or channels are located throughout the entire neuron plasma membrane of a neuron?
|
Na+ leak channels, K+ leak channels, and Na+/K+ pumps
|
|
These are important in establishing and maintaining the resting membrane potential of neurons.
|
Na+ leak channels, K+ leak channels, and Na+/K+ pumps
|
|
A typical neuron is functionally organized into these four segments:
|
1 - receptive segment
2 - initial segment 3 - conductive segment 4 - transmissive segment |
|
T/F Each of the four segments of a typical neuron differs in the primary types of channels and pumps located within its plasma membrane
|
True
|