Term
Nervous System
Sensory input - _____
Integration
Motor output - ______ |
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Definition
Nervous System
Sensory input - afferent
Integration
Motor output - efferent |
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Term
Nervous System
Processes and interprets sensory input
Makes decisions – _______
Dictates a response by activating ____ organs
Response – motor output |
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Definition
Processes and interprets sensory input
Makes decisions – integration
Dictates a response by activating effector organs
Response – motor output |
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Term
Basic Divisions of the Nervous System
Central nervous system (CNS):
_____ and _____
Integrating and command center
Peripheral nervous system (PNS)
____ the CNS
Consists of nerves extending from __ and _____
Cranial nerves
Spinal nerves
Peripheral nerves link all regions of the body to the CNS |
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Definition
Basic Divisions of the Nervous System
Central nervous system (CNS)
Brain and spinal cord
Integrating and command center
Peripheral nervous system (PNS)
Outside the CNS
Consists of nerves extending from brain and spinal cord
Cranial nerves
Spinal nerves
Peripheral nerves link all regions of the body to the CNS |
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Term
Sensory Input and Motor Output
Sensory (____) signals picked up by sensor receptors
Carried by nerve fibers of __ to the CNS
Motor (___) signals are carried away from the CNS
Innervate ___ and ____ |
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Definition
Sensory Input and Motor Output
Sensory (afferent) signals picked up by sensor receptors
Carried by nerve fibers of PNS to the CNS
Motor (efferent) signals are carried away from the CNS
Innervate muscles and glands |
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Term
Sensory Input and Motor Output
Divided according to region they serve
Somatic body region
Visceral body region
Results in four main subdivisions
Somatic _____
Visceral _____
Somatic ______
Visceral _____ |
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Definition
Sensory Input and Motor Output
Divided according to region they serve
Somatic body region
Visceral body region
Results in four main subdivisions
Somatic sensory
Visceral sensory
Somatic motor
Visceral motor |
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Term
Somatic sensory
General somatic senses – receptors are widely spread (5)senses
Proprioceptive senses – detect _____
Body sense – _____
Special somatic senses
(4) |
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Definition
Somatic sensory
General somatic senses – receptors are widely spread
Touch, pain, vibration, pressure, and temperature
Proprioceptive senses – detect stretch in tendons and muscle
Body sense – position and movement of body in space
Special somatic senses
Hearing, balance, vision, and smell |
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Term
| Visceral sensory General visceral senses –(5) Widely felt in digestive and urinary tracts, reproductive organs Special visceral senses – (1) |
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Definition
| Visceral sensory General visceral senses – stretch, pain, temperature, nausea, and hunger Widely felt in digestive and urinary tracts, reproductive organs Special visceral senses – taste |
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Term
Somatic motor
General somatic motor – signals _____ muscles
Under our voluntary control
Often called “voluntary nervous system” |
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Definition
Somatic motor
General somatic motor – signals contraction of skeletal muscles
Under our voluntary control
Often called “voluntary nervous system” |
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Term
Visceral motor
Regulates the contraction of _____
Makes up autonomic nervous system
Controls function of visceral organs
Often called “involuntary nervous system” |
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Definition
Visceral motor
Regulates the contraction of smooth and cardiac muscle
Makes up autonomic nervous system
Controls function of visceral organs
Often called “involuntary nervous system” |
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Term
Types of Sensory and Motor Information
Nervous Tissue
Cells are densely packed and intertwined
Two main cell types
___ – transmit electrical signals
____ (neuroglial cells) – nonexcitable
Surround and wrap neurons |
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Definition
Types of Sensory and Motor Information
Nervous Tissue
Cells are densely packed and intertwined
Two main cell types
Neurons – transmit electrical signals
Support cells (neuroglial cells) – nonexcitable
Surround and wrap neurons |
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Term
The Neuron
The human body contains billions of neurons
Basic structural unit of the nervous system, large and complex cells
Specialized cells conduct ____ along the ___ membrane |
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Definition
The Neuron
The human body contains billions of neurons
Basic structural unit of the nervous system, large and complex cells
Specialized cells conduct electrical impulses along the plasma membrane |
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Term
The Neuron
Other special characteristics
Longevity – can live and function for ____
Do not ____ – fetal neurons lose their ability to undergo mitosis; neural ____ are an exception in certain brain areas
High metabolic rate – require abundant ___ and ____ |
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Definition
The Neuron
Other special characteristics
Longevity – can live and function for a lifetime
Do not divide – fetal neurons lose their ability to undergo mitosis; neural stem cells are an exception in certain brain areas
High metabolic rate – require abundant oxygen and glucose |
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Term
The Cell Body
Cell body (_____)
Size varies from 5–140µm
Contains usual organelles plus other structures
____ bodies (Nissl bodies)
Clusters of rough ___ and ______
Stain darkly
____ – bundles of intermediate filaments
Form a network between _____ bodies
Most neuronal cell bodies
Located within the ___
Protected by bones of the skull and vertebral column
____ – clusters of cell bodies
Lie along nerves in the ___ |
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Definition
The Cell Body
Cell body (perikaryon)
Size varies from 5–140µm
Contains usual organelles plus other structures
Chromatophilic bodies (Nissl bodies)
Clusters of rough ER and free ribosomes
Stain darkly
Neurofibrils – bundles of intermediate filaments
Form a network between chromatophilic bodies
Most neuronal cell bodies
Located within the CNS
Protected by bones of the skull and vertebral column
Ganglia – clusters of cell bodies
Lie along nerves in the PNS |
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Term
Structure of a Typical Large Neuron
Neuron Processes
Armlike processes extend from cell bodies
Two types. Differ from each other in structure and function of their ___
Dendrites
Extensively branching from the cell body. More than 1
Transmit electrical signals (graded potentials) ___ the cell body
Chromatophilic bodies – only extend into the basal part of dendrites
Function as ____ sites
Axon
Neuron has only one
Impulse generator and conductor
Transmits impulses ___ from the cell body
Chromatophilic bodies are ____
No ___ synthesis in axon |
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Definition
Structure of a Typical Large Neuron
Neuron Processes
Armlike processes extend from cell bodies
Two types. Differ from each other in structure and function of their PM
Dendrites
Extensively branching from the cell body. More than 1
Transmit electrical signals (graded potentials) toward the cell body
Chromatophilic bodies – only extend into the basal part of dendrites
Function as receptive sites
Axon
Neuron has only one
Impulse generator and conductor
Transmits impulses away from the cell body
Chromatophilic bodies are absent
No protein synthesis in axon |
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Term
Axons
____filaments, ___ microfilaments, and micro____
Provide ____ along length of axon
Aid in the transport of ____ to and from the cell body
Axonal transport
Branches along length are infrequent
Axon collaterals
Multiple branches at end of axon
Terminal branches (telodendria)
~10000/neuron
End in knobs called axon terminals (also called end bulbs or boutons) |
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Definition
Axons
Neurofilaments, actin microfilaments, and microtubules
Provide strength along length of axon
Aid in the transport of substances to and from the cell body
Axonal transport
Branches along length are infrequent
Axon collaterals
Multiple branches at end of axon
Terminal branches (telodendria)
~10000/neuron
End in knobs called axon terminals (also called end bulbs or boutons) |
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Term
Neuron Processes
Nerve impulse
Generated at the ____ segment of the axon
Conducted along the ____
Releases _____ at axon terminals
_____– excite or inhibit neurons
Neuron receives and sends signals |
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Definition
Neuron Processes
Nerve impulse
Generated at the initial segment of the axon
Conducted along the axon
Releases neurotransmitters at axon terminals
Neurotransmitters – excite or inhibit neurons
Neuron receives and sends signals |
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Term
Synapses
Site at which neurons _____
Signals pass across synapse in ___ direction
Presynaptic neuron
Conducts signal ____ a synapse
Postsynaptic neuron
Transmits electrical activity ___ from a synapse |
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Definition
Synapses
Site at which neurons communicate
Signals pass across synapse in one direction
Presynaptic neuron
Conducts signal toward a synapse
Postsynaptic neuron
Transmits electrical activity away from a synapse |
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Term
Two Neurons Communicating at a Synapse
Types of Synapses
Axodendritic
Between ____ of one neuron and _____ of another
Most common type of synapse |
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Definition
Two Neurons Communicating at a Synapse
Types of Synapses
Axodendritic
Between axon terminals of one neuron and dendrites of another
Most common type of synapse |
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Term
Two Neurons Communicating at a Synapse
Types of Synapses
Axosomatic
Between ____ and neuronal ______
Axoaxonic, dendrodendritic, and dendrosomatic
Between two axons, two dentrites or between a dentrite and a cell body
Uncommon types of synapses |
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Definition
Two Neurons Communicating at a Synapse
Types of Synapses
Axosomatic
Between axons and neuronal cell bodies
Axoaxonic, dendrodendritic, and dendrosomatic
Between two dentrites or between a dentrite and a cell body
Uncommon types of synapses |
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Term
Some Important Types of Synapses
Synapses
Elaborate cell _____
Axodendritic synapses – representative type
Synaptic vesicles on ____ side
Membrane-bound sacs containing _____
Mitochondria ____ in axon terminals
Synaptic cleft separates the plasma membrane of the two ____ |
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Definition
Some Important Types of Synapses
Synapses
Elaborate cell junctions
Axodendritic synapses – representative type
Synaptic vesicles on presynaptic side
Membrane-bound sacs containing neurotransmitters
Mitochondria abundant in axon terminals
Synaptic cleft separates the plasma membrane of the two neurons |
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Term
Action Potentials on Axons
Strong stimulus applied to the ____triggers
Nerve impulse or ____
Membrane becomes _____ externally
Impulse travels the length of the axon
Membrane repolarizes itself |
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Definition
Action Potentials on Axons
Strong stimulus applied to the axon triggers
Nerve impulse or action potential
Membrane becomes negative externally
Impulse travels the length of the axon
Membrane repolarizes itself |
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Term
Excitatory synapses
Neurotransmitters alter the ____ of the postsynaptic membrane
Leads to an inflow of ___ ions
Depolarizes the postsynaptic membrane
Drives the postsynaptic neuron toward _____ generation. |
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Definition
Excitatory synapses
Neurotransmitters alter the permeability of the postsynaptic membrane
Leads to an inflow of positive ions
Depolarizes the postsynaptic membrane
Drives the postsynaptic neuron toward impulse generation |
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Term
Inhibitory synapses
The external surface of the postsynaptic membrane becomes more ____
Reduces the ability of the postsynaptic neuron to generate an _____ |
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Definition
Inhibitory synapses
The external surface of the postsynaptic membrane becomes more positive
Reduces the ability of the postsynaptic neuron to generate an action potential |
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Term
Structural classification
According to the number of process that extend from cell body
_____ – possess more than two processes
Numerous dendrites and one axon
Most common
_____ – possess two processes
Extend opposite side of cell body
Rare neurons – found in some ____ organs
____ - pseudounipolar – possess one short, single process
Start as bipolar neurons during development
Make up _____ neurons |
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Definition
Structural classification
According to the number of process that extend from cell body
Multipolar – possess more than two processes
Numerous dendrites and one axon
Most common
Bipolar – possess two processes
Extend opposite side of cell body
Rare neurons – found in some special sensory organs
Unipolar - pseudounipolar – possess one short, single process
Start as bipolar neurons during development
Make up sensory neurons |
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Term
Functional Classification of Neurons
According to the direction the nerve impulse travels relative to CNS
_____ (afferent) neurons – transmit impulses toward the CNS from ___receptors in the PNS
Virtually all are __polar neurons
Cell bodies in ___ outside the CNS
Short, single process divides into:
*The ____ process – runs centrally into the CNS
*The _____ process – extends ____ to the receptors |
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Definition
Functional Classification of Neurons
According to the direction the nerve impulse travels relative to CNS
Sensory (afferent) neurons – transmit impulses toward the CNS from sensory receptors in the PNS
Virtually all are unipolar neurons
Cell bodies in ganglia outside the CNS
Short, single process divides into
The central process – runs centrally into the CNS
The peripheral process – extends peripherally to the receptors |
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Term
Functional Classification of Neurons
____ (efferent) neurons
Carry impulses away from the CNS to effector organs
Most motor neurons are _____polar
Cell bodies are within the CNS
Form junctions with effector cells such as ____, ____ |
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Definition
Functional Classification of Neurons
Motor (efferent) neurons
Carry impulses away from the CNS to effector organs
Most motor neurons are multipolar
Cell bodies are within the CNS
Form junctions with effector cells such as muscles, glands |
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Term
______ (association neurons) – most are _____
Lie between motor and sensory neurons
Confined entirely to the CNS |
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Definition
Interneurons (association neurons) – most are multipolar
Lie between motor and sensory neurons
Confined entirely to the CNS |
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Term
Supporting Cells
Non-nervous cells. Each type has unique function
Six types of supporting cells
___ in the CNS
___ in the PNS
Provide supportive functions for neurons
Cover _____ regions of the neurons in insulating nerve ___ from each other |
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Definition
Supporting Cells
Non-nervous cells. Each type has unique function
Six types of supporting cells
Four in the CNS
Two in the PNS
Provide supportive functions for neurons
Cover nonsynaptic regions of the neurons in insulating nerve fibers from each other |
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Term
Supporting Cells (Neuroglial Cells) in the CNS
Neuroglia – usually only refers to supporting cells in the CNS
Glial cells have _____ processes and a central cell ___
Outnumber neurons __ to 1
Make up ___ the mass of the brain
Can divide throughout life |
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Definition
Supporting Cells (Neuroglial Cells) in the CNS
Neuroglia – usually only refers to supporting cells in the CNS
Glial cells have branching processes and a central cell body
Outnumber neurons 10 to 1
Make up half the mass of the brain
Can divide throughout life |
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Term
Types of neuroglial cells
______ – most abundant glial cell type
Take up and release ___ to control the environment around neurons
Recapture and recycle __________
Involved with ____ formation in developing neural tissue
Produce _____ necessary for neural growth
Propagate _____ signals that may be involved in memory |
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Definition
Types of neuroglial cells
Astrocytes – most abundant glial cell type
Take up and release ions to control the environment around neurons
Recapture and recycle neurotransmitters
Involved with synapse formation in developing neural tissue
Produce molecules necessary for neural growth
Propagate calcium signals that may be involved in memory |
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Term
Types of neuroglial cells
_____ – smallest and least abundant
Phagocytes – the _____ of the CNS
Engulf invading microorganisms and dead neurons
Derive from blood cells called monocytes |
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Definition
Types of neuroglial cells
Microglia – smallest and least abundant
Phagocytes – the macrophages of the CNS
Engulf invading microorganisms and dead neurons
Derive from blood cells called monocytes |
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Term
______ cells
Line the central cavity of the spinal cord and brain
Bear _____ – help circulate the cerebrospinal fluid |
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Definition
Ependymal cells
Line the central cavity of the spinal cord and brain
Bear cilia – help circulate the cerebrospinal fluid |
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Term
______ – have few branches
Wrap their cell processes around axons in CNS
Produce myelin sheaths |
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Definition
Oligodendrocytes – have few branches
Wrap their cell processes around axons in CNS
Produce myelin sheaths |
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Term
Supporting Cells in the PNS
____ cells – surround neuron cell bodies within ganglia
____ cells (neurolemmocytes) – surround axons in the PNS
Form myelin sheath around axons of the PNS
Form an insulating layer
Prevent leakage of ______ current
Increase the ___ of impulse conduction |
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Definition
Supporting Cells in the PNS
Satellite cells – surround neuron cell bodies within ganglia
Schwann cells (neurolemmocytes) – surround axons in the PNS
Form myelin sheath around axons of the PNS
Form an insulating layer
Prevent leakage of electrical current
Increase the speed of impulse conduction |
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Term
Myelin Sheaths in the PNS
Formed by ____ cells
Develop during ____ period and in the __ year of postnatal life
___ cells wrap in concentric layers around the ____
Cover the axon in a tightly packed coil of membranes |
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Definition
Myelin Sheaths in the PNS
Formed by Schwann cells
Develop during fetal period and in the first year of postnatal life
Schwann cells wrap in concentric layers around the axon
Cover the axon in a tightly packed coil of membranes |
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Term
Myelin Sheaths in the PNS
Nodes of ____ – gaps along axon
Thick axons are myelinated
Thin axons are unmyelinated |
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Definition
Myelin Sheaths in the PNS
Nodes of Ranvier – gaps along axon
Thick axons are myelinated
Thin axons are unmyelinated |
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Term
Myelin Sheaths in the CNS
______ form the myelin sheaths in the CNS
Have multiple processes
Coil around ___ different axons |
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Definition
Myelin Sheaths in the CNS
Oligodendrocytes form the myelin sheaths in the CNS
Have multiple processes
Coil around several different axons |
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Term
Nerves – cordlike organs in the ___
Consists of numerous ____ wrapped in connective tissue
Axon is surrounded by ____ cells |
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Definition
Nerves – cordlike organs in the PNS
Consists of numerous axons wrapped in connective tissue
Axon is surrounded by Schwann cells |
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Term
_____ – layer of delicate connective tissue surrounding the axon
______ – connective tissue wrapping surrounding a nerve fascicle
______ – whole nerve is surrounded by tough fibrous sheath |
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Definition
Endoneurium – layer of delicate connective tissue surrounding the axon
Perineurium – connective tissue wrapping surrounding a nerve fascicle
Epineurium – whole nerve is surrounded by tough fibrous sheath |
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Term
| Nerve ____ – groups of axons bound into bundles |
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Definition
| Nerve fascicles – groups of axons bound into bundles |
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Term
Reflex arcs – simple chains of neurons
Explain reflex behaviors
Responsible for reflexes
Rapid, ______ responses
Can be visceral or _____ |
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Definition
Reflex arcs – simple chains of neurons
Explain reflex behaviors
Responsible for reflexes
Rapid, autonomic motor responses
Can be visceral or somatic |
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Term
Five Essential Components to the Reflex Arc
_____ – site where stimulus acts
______ neuron – transmits afferent impulses to the CNS
_______ center – consists of one or more synapses in the CNS
_____ neuron – conducts efferent impulses from integration center to an effector
____ – muscle or gland cell
Responds to efferent impulses
Contracting or secreting |
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Definition
Five Essential Components to the Reflex Arc
Receptor – site where stimulus acts
Sensory neuron – transmits afferent impulses to the CNS
Integration center – consists of one or more synapses in the CNS
Motor neuron – conducts efferent impulses from integration center to an effector
Effector – muscle or gland cell
Responds to efferent impulses
Contracting or secreting |
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Term
Types of Reflexes
_____ reflex – simplest of all reflexes
Just one synapse
The fastest of all reflexes
Example – knee-jerk reflex
______ reflex – more common type of reflex
Most have a single interneuron between the sensory and motor neuron
Example – withdrawal reflexes |
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Definition
Types of Reflexes
Monosynaptic reflex – simplest of all reflexes
Just one synapse
The fastest of all reflexes
Example – knee-jerk reflex
Polysynaptic reflex – more common type of reflex
Most have a single interneuron between the sensory and motor neuron
Example – withdrawal reflexes |
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Term
Input Processing
____ processing – neurons pass a signal to a specific destination along a single pathway from one to another
______ processing – input is delivered along many pathways; a single sensory stimulus results in multiple perceptions |
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Definition
Input Processing
Serial processing – neurons pass a signal to a specific destination along a single pathway from one to another
Parallel processing – input is delivered along many pathways; a single sensory stimulus results in multiple perceptions |
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Term
CNS divided into regions of __ matter and ____ matter
Gray matter in the spinal cord
_-shaped region – surrounds central cavity
Dorsal half contains cell bodies of ____
Ventral half contains cell bodies of ___ neurons
Cell bodies are clustered in the ___ matter |
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Definition
CNS divided into regions of gray matter and white matter
Gray matter in the spinal cord
H-shaped region – surrounds central cavity
Dorsal half contains cell bodies of interneurons
Ventral half contains cell bodies of motor neurons
Cell bodies are clustered in the gray matter |
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Term
White matter in the spinal cord
Located ____ to the gray matter
Contains no neuronal cell bodies, but millions of ____
Myelin sheath – white color
Consists of ____ running between different parts of the CNS
_____ – bundles of axons traveling to similar destinations |
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Definition
White matter in the spinal cord
Located externally to the gray matter
Contains no neuronal cell bodies, but millions of axons
Myelin sheath – white color
Consists of axons running between different parts of the CNS
Tracts – bundles of axons traveling to similar destinations |
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Term
Nervous Tissue Throughout Life
Nervous system develops from ______ |
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Definition
Nervous Tissue Throughout Life
Nervous system develops from ectoderm |
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