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Functions of Nervous System

Functions of Nervous System
231問 • 1年前
  • Bear4
    • 通報

    問題一覧

  • 1

    Cells communicate via electrical & chemical signals –Rapid/specific, usually cause almost immediate responses

    Nervous System

  • 2

    is master controlling & communicating system of body

    Nervous System

  • 3

    Nervous system has three overlapping functions

    1) Sensory Input -Information gathered by sensory receptors about internal & external changes, 2) Integration -Processing & interpretation of sensory input, 3) Motor Output -Activation of Effector Organs (muscles & glands) produces a response

  • 4

    Information gathered by sensory receptors about internal & external changes

    Sensory Input

  • 5

    Processing & interpretation of sensory input

    Integration

  • 6

    Activation of Effector Organs (muscles & glands) produces a response

    Motor Output

  • 7

    Divided into two principal parts

    Central Nervous System (CNS) -Brain & spinal cord of dorsal body cavity, Peripheral Nervous System (PNS) –Mainly nerves that extend from brain & spinal cord

  • 8

    Central Nervous System (CNS) left or right

    left

  • 9

    Peripheral Nervous System (PNS) left or right

    right

  • 10

    Brain & spinal cord of dorsal body cavity –Integration & control center •Interprets sensory input & dictates motor output

    Central Nervous System (CNS)

  • 11

    –Mainly nerves that extend from brain & spinal cord •Spinal Nerves to & from Spinal Cord •Cranial Nerves (CN) to & from Brain

    Peripheral Nervous System (PNS)

  • 12

    PNS has two functional divisions

    Sensory (Afferent) division -Somatic sensory fibers: convey impulses from skin, skeletal muscles, & joints to CNS -Visceral sensory fibers: convey impulses from visceral organs to CNS, Motor (Efferent) division -Transmits impulses from CNS to effector organs –Muscles & glands ~Two divisions~ •Somatic Nervous System •Autonomic Nervous System

  • 13

    Sensory (Afferent) division

    -Somatic sensory fibers: convey impulses from skin, skeletal muscles, & joints to CNS, -Visceral sensory fibers: convey impulses from visceral organs to CNS, This is 1/2 of PNS functional divisions

  • 14

    Motor (Efferent) division

    Transmits impulses from CNS to effector organs –Muscles & glands, Two divisions: –Somatic Nervous System –Autonomic Nervous System, 2/2 of PNS two functional divisions

  • 15

    Somatic sensory fibers

    convey impulses from skin, skeletal muscles, & joints to CNS, In PNS, Sensory (Afferent) division

  • 16

    Visceral sensory fibers

    convey impulses from visceral organs to CNS, In PNS, Sensory (Afferent) division

  • 17

    Transmits impulses from CNS to effector organs –Muscles & glands

    Motor (Efferent) division, Two divisions –Somatic Nervous System –Autonomic Nervous System

  • 18

    Motor (Efferent) division Transmits impulses from CNS to effector organs –Muscles & glands (Two divisions)

    –Autonomic Nervous System, –Somatic Nervous System

  • 19

    Somatic Nervous System:

    Motor (Efferent) division, Voluntary

  • 20

    Autonomic Nervous System

    Involuntary, Motor (Efferent) division

  • 21

    conduct impulses from CNS to skeletal muscle -Conscious control of skeletal muscles

    Somatic Nervous System: Voluntary, Functions of Nervous System

  • 22

    Consists of visceral motor nerve fibers –Regulates smooth muscle, cardiac muscle, & glands –Two functional subdivisions: work in opposition to each other ●Sympathetic: Fight or Flight ●Parasympathetic: Rest & Digest

    Autonomic Nervous System: Involuntary, Functions of Nervous System

  • 23

    Autonomic Nervous System: Involuntary -Two functional subdivisions: work in opposition to each other

    Sympathetic: Fight or Flight, Parasympathetic: Rest & Digest

  • 24

    Sympathetic

    Autonomic Nervous System: Involuntary, Fight or Flight

  • 25

    Parasympathetic

    Rest & Digest, Autonomic Nervous System: Involuntary

  • 26

    Nervous tissue consists of two principal cell types

    Neuroglia (Glial Cells): 4 small cells that surround & wrap delicate neurons ●Astrocytes ●Microglial cells ●Ependymal cells ●Oligodendrocytes, Neurons (Nerve Cells): excitable cells that transmit electrical signals

  • 27

    _______(Glial Cells): 4 small cells that surround & wrap delicate neurons________

    Neuroglia, ●Astrocytes ●Microglial cells ●Ependymal cells ●Oligodendrocytes

  • 28

    Neuroglia (Glial Cells): 4 small cells that surround & wrap delicate neurons

    Astrocytes, Microglial cells, Ependymal cells, Oligodendrocytes

  • 29

    ____ (Nerve Cells): excitable cells that transmit electrical signals

    Neurons

  • 30

    Most abundant, versatile, & highly branched of glial cells

    Neuroglia of the CNS: Astrocytes

  • 31

    Cling to neurons, synaptic endings, & capillaries •Functions include: –Support & brace neurons –Play role in exchanges between capillaries & neurons –Guide migration of young neurons –Control chemical environment around neurons –Respond to nerve impulses & neurotransmitters –Influence neuronal functioning –Participate in information processing in brain

    Neuroglia of the CNS: Astrocytes

  • 32

    Migrate toward injured neurons •Can transform to phagocytize microorganisms & neuronal debris

    Neuroglia of the CNS: Microglial Cells

  • 33

    May be ciliated: beat to circulate CSF •Line the central cavities of the brain & spinal column •Form permeable barrier between cerebrospinal fluid (CSF) in cavities & tissue fluid bathing CNS cells

    Neuroglia of the CNS: Ependymal Cells

  • 34

    Branched cells •Processes wrap CNS nerve fibers, forming insulating Myelin Sheaths in thicker nerve fibers sheaths around CNS nerve fibers

    Neuroglia of the CNS: Oligodendrocytes

  • 35

    function similar to Astrocytes –Surround neuron cell bodies in PNS

    Satellite Cells, Red (?), Neuroglia of PNS

  • 36

    (Neurolemmocytes): function similar to Oligodendrocytes –Surround all peripheral nerve fibers & form myelin sheaths in thicker nerve fibers –Vital to regeneration of damaged peripheral nerve fibers

    Green (?), Schwann Cells, Neuroglia of PNS

  • 37

    Schwann Cells (Neurolemmocytes): function similar to

    Oligodendrocytes

  • 38

    Satellite Cells: function similar to

    Astrocytes

  • 39

    Schwann Cells (Neurolemmocytes): function similar to

    Oligodendrocytes

  • 40

    Neurons:

    structural units of the CNS/PNS

  • 41

    Large, highly specialized cells that conduct impulses •Special characteristics –Extreme longevity (lasts a person’s lifetime) –Amitotic, with few exceptions –High metabolic rate: requires continuous supply of oxygen & glucose

    Neurons: structural units of the CNS/PNS

  • 42

    All have Cell Body & one or more processes

    Neurons: structural units of the CNS/PNS

  • 43

    (Neurons) Tracts

    Bundles of neuron processes in CNS

  • 44

    (Neurons) Nerves

    Bundles of neuron processes in PNS

  • 45

    Biosynthetic center of

    Neuron

  • 46

    Biosynthetic center of Neuron

    Synthesizes proteins, membranes, chemicals, Rough ER (chromatophilic substance, or Nissl bodies), Contains Nucleus with Nucleolus

  • 47

    In most, plasma membrane is part of receptive region that receives input info from other neurons

    Neuron Cell Body/Perikaryon/Soma

  • 48

    Most neuron cell bodies are located in CNS

    Nuclei: clusters of neuron cell bodies in CNS, Ganglia: clusters of neuron cell bodies in PNS

  • 49

    clusters of neuron cell bodies in CNS

    Nuclei

  • 50

    clusters of neuron cell bodies in PNS

    Ganglia

  • 51

    both neuron cell bodies & their processes

    CNS contains

  • 52

    chiefly neuron processes

    PNS contains

  • 53

    Armlike processes that extend from cell body

    Dendrites

  • 54

    Motor neurons can contain 100s of these short, tapering, diffusely branched processes –Contain same organelles as Soma

    Neuron Processes: Dendrites

  • 55

    Receptive (input) region of neuron •Convey incoming messages toward cell body as graded potentials (short distance signals) •In many brain areas, finer dendrites are highly specialized to collect information –Contain Dendritic Spines, appendages with bulbous or spiky ends

    Neuron Processes: Dendrites

  • 56

    can be short/absent; or comprises almost entire length of cell ●Can be over 1 meter long

    Neuron Processes: Axon

  • 57

    cone-shaped area at the start of the Axon

    Axon Hillock

  • 58

    long axons

    Nerve Fibers

  • 59

    occasional branches

    Axon Collaterals

  • 60

    branch profusely at their terminus ●Can number as many as 10,000 terminal branches

    Axon Terminals or Terminal Boutons

  • 61

    Functional Characteristics –Conducting region of Neuron –Generates nerve impulses & transmits them along Axolemma (cell membrane) to Axon Terminal

    Neuron Processes: Axon

  • 62

    secretes Neurotransmitters- released into extracellular space which can excite of inhibit neurons it contacts

    Terminal

  • 63

    rely on Soma to renew proteins & membranes

    Axons

  • 64

    have efficient internal transport mechanisms ●Molecules & organelles are moved along axons by motor proteins & cytoskeletal elements -Quickly decay if cut or damaged

    Neuron Processes: Axon

  • 65

    Neuron Processes: Axon Movement occurs in both directions

    Anterograde: away from cell body, Retrograde: toward cell body

  • 66

    away from cell body

    Anterograde

  • 67

    toward cell body

    Retrograde

  • 68

    Ex: mitochondria, cytoskeletal elements, membrane components, enzymes

    Anterograde

  • 69

    Ex: organelles to be degraded, signal molecules, viruses, & bacterial toxins

    Retrograde

  • 70

    Certain viruses & bacterial toxins damage neural tissues by using

    retrograde axonal transport

  • 71

    Ex: Poliomyelitis, Rabies, Herpes Simplex & Tetanus toxin

    Retrograde axonal transport

  • 72

    Viruses containing “corrected” genes or microRNA to suppress defective genes can enter cell through

    retrograde transport

  • 73

    Whitish, protein-lipid substance –Protect and electrically insulate axon –Increase speed of nerve impulse transmission

    Myelin Sheath

  • 74

    segmented sheath surrounds most long or large-diameter axons

    Myelinated Fibers

  • 75

    do not contain sheath –Conduct impulses more slowly

    Non-Myelinated Fibers

  • 76

    Formed by Schwann Cells –Wraps around axon in jelly roll fashion –One cell forms one segment of myelin sheath

    PNS Myelination

  • 77

    peripheral bulge containing nucleus & most of cytoplasm

    Outer Collar of Perinuclear Cytoplasm (Neurilemma):

  • 78

    Plasma membranes have less protein –No channels or carriers, so good electrical insulators –Interlocking proteins bind adjacent myelin membranes

    PNS Myelination

  • 79

    A Schwann cell envelops an axon.

    1

  • 80

    The Schwann cell then rotates around the axon, wrapping its plasma membrane loosely around it in successive layers.

    2

  • 81

    What is step 3

    The Schwann cell then rotates around the axon, wrapping its plasma membrane loosely around it in successive layers., Has Myelin sheath

  • 82

    Myelin sheath

    1

  • 83

    Outer collar of perinuclear cytoplasm (of Schwann cell)

    2

  • 84

    –Gaps between Schwann cells –Sites where axon collaterals can emerge ●Nodes of Ranvier

    Myelin Sheath Gaps

  • 85

    –Thin fibers not wrapped in Myelin; surrounded by Schwann Cells but no coiling; one cell may surround 15 different fibers

    Non-Myelinated fibers

  • 86

    Neuron Processes: CNS Myelination •Formed by processes of _______ not whole cells –Each cell can wrap up to 60 axons at once –Myelin sheath gap is present –No outer collar of perinuclear cytoplasm due to wide distribution

    Oligodendrocytes

  • 87

    are unmyelinated, but covered by long extensions of adjacent neuroglia

    Thinnest fibers

  • 88

    regions of brain & spinal cord with dense collections of myelinated fibers ●Usually fiber tracts

    White matter

  • 89

    mostly neuron cell bodies & non-myelinated fibers

    Gray matter

  • 90

    Structural Classification of Neurons: Multipolar

    3+ processes (1 axon, others dendrites)

  • 91

    Structural Classification of Neurons: Bipolar

    2 processes (1 axon, 1 dendrite) –Rare (ex: retina & olfactory mucosa)

  • 92

    Structural Classification of Neurons: Unipolar

    one T-like process (two axons) –Also called Pseudounipolar

  • 93

    Structural Classification of Neurons: (distal) process: associated with sensory receptor

    Peripheral

  • 94

    Structural Classification of Neurons: (central) process: enters CNS

    Proximal

  • 95

    Many processes extend from the cell body. All are dendrites except for a single axon.

    Multipolar

  • 96

    Two processes extend from the cell body. One is a fused dendrite, the other is an axon.

    Bipolar

  • 97

    One process extends from the cell body and forms central and peripheral processes, which together comprise an axon.

    Unipolar (Pseudounipolar)

  • 98

    MULTIPOLAR: Receptive region (receives stimulus).

    blue

  • 99

    MULTIPOLAR: Conducting region (generates/transmits action potential).

    green

  • 100

    MULTIPOLAR: Secretory region (axon terminals release neurotransmitters).

    red

    • Muscles

    Muscles

    Bear4 · 28問 · 1年前

    Muscles

    Muscles

    28問 • 1年前
    Bear4

    Muscles Lab 3

    Muscles Lab 3

    Bear4 · 102問 · 1年前

    Muscles Lab 3

    Muscles Lab 3

    102問 • 1年前
    Bear4

    The Central Nervous System

    The Central Nervous System

    Bear4 · 111問 · 1年前

    The Central Nervous System

    The Central Nervous System

    111問 • 1年前
    Bear4

    Chapter 13 The Peripheral Nervous System & Reflex

    Chapter 13 The Peripheral Nervous System & Reflex

    Bear4 · 94問 · 1年前

    Chapter 13 The Peripheral Nervous System & Reflex

    Chapter 13 The Peripheral Nervous System & Reflex

    94問 • 1年前
    Bear4

    Part B: The Peripheral Nervous System & Reflex Activity

    Part B: The Peripheral Nervous System & Reflex Activity

    Bear4 · 31問 · 1年前

    Part B: The Peripheral Nervous System & Reflex Activity

    Part B: The Peripheral Nervous System & Reflex Activity

    31問 • 1年前
    Bear4

    Part C: The Peripheral Nervous System & Reflex Activity

    Part C: The Peripheral Nervous System & Reflex Activity

    Bear4 · 71問 · 1年前

    Part C: The Peripheral Nervous System & Reflex Activity

    Part C: The Peripheral Nervous System & Reflex Activity

    71問 • 1年前
    Bear4

    Part D: The Peripheral Nervous System & Reflex

    Part D: The Peripheral Nervous System & Reflex

    Bear4 · 55問 · 1年前

    Part D: The Peripheral Nervous System & Reflex

    Part D: The Peripheral Nervous System & Reflex

    55問 • 1年前
    Bear4

    Chapter 14: The Autonomic Nervous System

    Chapter 14: The Autonomic Nervous System

    Bear4 · 84問 · 1年前

    Chapter 14: The Autonomic Nervous System

    Chapter 14: The Autonomic Nervous System

    84問 • 1年前
    Bear4

    Unit 1

    Unit 1

    Bear4 · 82問 · 1年前

    Unit 1

    Unit 1

    82問 • 1年前
    Bear4

    Unit 3

    Unit 3

    Bear4 · 122問 · 1年前

    Unit 3

    Unit 3

    122問 • 1年前
    Bear4

    Unit 4

    Unit 4

    Bear4 · 33問 · 1年前

    Unit 4

    Unit 4

    33問 • 1年前
    Bear4

    問題一覧

  • 1

    Cells communicate via electrical & chemical signals –Rapid/specific, usually cause almost immediate responses

    Nervous System

  • 2

    is master controlling & communicating system of body

    Nervous System

  • 3

    Nervous system has three overlapping functions

    1) Sensory Input -Information gathered by sensory receptors about internal & external changes, 2) Integration -Processing & interpretation of sensory input, 3) Motor Output -Activation of Effector Organs (muscles & glands) produces a response

  • 4

    Information gathered by sensory receptors about internal & external changes

    Sensory Input

  • 5

    Processing & interpretation of sensory input

    Integration

  • 6

    Activation of Effector Organs (muscles & glands) produces a response

    Motor Output

  • 7

    Divided into two principal parts

    Central Nervous System (CNS) -Brain & spinal cord of dorsal body cavity, Peripheral Nervous System (PNS) –Mainly nerves that extend from brain & spinal cord

  • 8

    Central Nervous System (CNS) left or right

    left

  • 9

    Peripheral Nervous System (PNS) left or right

    right

  • 10

    Brain & spinal cord of dorsal body cavity –Integration & control center •Interprets sensory input & dictates motor output

    Central Nervous System (CNS)

  • 11

    –Mainly nerves that extend from brain & spinal cord •Spinal Nerves to & from Spinal Cord •Cranial Nerves (CN) to & from Brain

    Peripheral Nervous System (PNS)

  • 12

    PNS has two functional divisions

    Sensory (Afferent) division -Somatic sensory fibers: convey impulses from skin, skeletal muscles, & joints to CNS -Visceral sensory fibers: convey impulses from visceral organs to CNS, Motor (Efferent) division -Transmits impulses from CNS to effector organs –Muscles & glands ~Two divisions~ •Somatic Nervous System •Autonomic Nervous System

  • 13

    Sensory (Afferent) division

    -Somatic sensory fibers: convey impulses from skin, skeletal muscles, & joints to CNS, -Visceral sensory fibers: convey impulses from visceral organs to CNS, This is 1/2 of PNS functional divisions

  • 14

    Motor (Efferent) division

    Transmits impulses from CNS to effector organs –Muscles & glands, Two divisions: –Somatic Nervous System –Autonomic Nervous System, 2/2 of PNS two functional divisions

  • 15

    Somatic sensory fibers

    convey impulses from skin, skeletal muscles, & joints to CNS, In PNS, Sensory (Afferent) division

  • 16

    Visceral sensory fibers

    convey impulses from visceral organs to CNS, In PNS, Sensory (Afferent) division

  • 17

    Transmits impulses from CNS to effector organs –Muscles & glands

    Motor (Efferent) division, Two divisions –Somatic Nervous System –Autonomic Nervous System

  • 18

    Motor (Efferent) division Transmits impulses from CNS to effector organs –Muscles & glands (Two divisions)

    –Autonomic Nervous System, –Somatic Nervous System

  • 19

    Somatic Nervous System:

    Motor (Efferent) division, Voluntary

  • 20

    Autonomic Nervous System

    Involuntary, Motor (Efferent) division

  • 21

    conduct impulses from CNS to skeletal muscle -Conscious control of skeletal muscles

    Somatic Nervous System: Voluntary, Functions of Nervous System

  • 22

    Consists of visceral motor nerve fibers –Regulates smooth muscle, cardiac muscle, & glands –Two functional subdivisions: work in opposition to each other ●Sympathetic: Fight or Flight ●Parasympathetic: Rest & Digest

    Autonomic Nervous System: Involuntary, Functions of Nervous System

  • 23

    Autonomic Nervous System: Involuntary -Two functional subdivisions: work in opposition to each other

    Sympathetic: Fight or Flight, Parasympathetic: Rest & Digest

  • 24

    Sympathetic

    Autonomic Nervous System: Involuntary, Fight or Flight

  • 25

    Parasympathetic

    Rest & Digest, Autonomic Nervous System: Involuntary

  • 26

    Nervous tissue consists of two principal cell types

    Neuroglia (Glial Cells): 4 small cells that surround & wrap delicate neurons ●Astrocytes ●Microglial cells ●Ependymal cells ●Oligodendrocytes, Neurons (Nerve Cells): excitable cells that transmit electrical signals

  • 27

    _______(Glial Cells): 4 small cells that surround & wrap delicate neurons________

    Neuroglia, ●Astrocytes ●Microglial cells ●Ependymal cells ●Oligodendrocytes

  • 28

    Neuroglia (Glial Cells): 4 small cells that surround & wrap delicate neurons

    Astrocytes, Microglial cells, Ependymal cells, Oligodendrocytes

  • 29

    ____ (Nerve Cells): excitable cells that transmit electrical signals

    Neurons

  • 30

    Most abundant, versatile, & highly branched of glial cells

    Neuroglia of the CNS: Astrocytes

  • 31

    Cling to neurons, synaptic endings, & capillaries •Functions include: –Support & brace neurons –Play role in exchanges between capillaries & neurons –Guide migration of young neurons –Control chemical environment around neurons –Respond to nerve impulses & neurotransmitters –Influence neuronal functioning –Participate in information processing in brain

    Neuroglia of the CNS: Astrocytes

  • 32

    Migrate toward injured neurons •Can transform to phagocytize microorganisms & neuronal debris

    Neuroglia of the CNS: Microglial Cells

  • 33

    May be ciliated: beat to circulate CSF •Line the central cavities of the brain & spinal column •Form permeable barrier between cerebrospinal fluid (CSF) in cavities & tissue fluid bathing CNS cells

    Neuroglia of the CNS: Ependymal Cells

  • 34

    Branched cells •Processes wrap CNS nerve fibers, forming insulating Myelin Sheaths in thicker nerve fibers sheaths around CNS nerve fibers

    Neuroglia of the CNS: Oligodendrocytes

  • 35

    function similar to Astrocytes –Surround neuron cell bodies in PNS

    Satellite Cells, Red (?), Neuroglia of PNS

  • 36

    (Neurolemmocytes): function similar to Oligodendrocytes –Surround all peripheral nerve fibers & form myelin sheaths in thicker nerve fibers –Vital to regeneration of damaged peripheral nerve fibers

    Green (?), Schwann Cells, Neuroglia of PNS

  • 37

    Schwann Cells (Neurolemmocytes): function similar to

    Oligodendrocytes

  • 38

    Satellite Cells: function similar to

    Astrocytes

  • 39

    Schwann Cells (Neurolemmocytes): function similar to

    Oligodendrocytes

  • 40

    Neurons:

    structural units of the CNS/PNS

  • 41

    Large, highly specialized cells that conduct impulses •Special characteristics –Extreme longevity (lasts a person’s lifetime) –Amitotic, with few exceptions –High metabolic rate: requires continuous supply of oxygen & glucose

    Neurons: structural units of the CNS/PNS

  • 42

    All have Cell Body & one or more processes

    Neurons: structural units of the CNS/PNS

  • 43

    (Neurons) Tracts

    Bundles of neuron processes in CNS

  • 44

    (Neurons) Nerves

    Bundles of neuron processes in PNS

  • 45

    Biosynthetic center of

    Neuron

  • 46

    Biosynthetic center of Neuron

    Synthesizes proteins, membranes, chemicals, Rough ER (chromatophilic substance, or Nissl bodies), Contains Nucleus with Nucleolus

  • 47

    In most, plasma membrane is part of receptive region that receives input info from other neurons

    Neuron Cell Body/Perikaryon/Soma

  • 48

    Most neuron cell bodies are located in CNS

    Nuclei: clusters of neuron cell bodies in CNS, Ganglia: clusters of neuron cell bodies in PNS

  • 49

    clusters of neuron cell bodies in CNS

    Nuclei

  • 50

    clusters of neuron cell bodies in PNS

    Ganglia

  • 51

    both neuron cell bodies & their processes

    CNS contains

  • 52

    chiefly neuron processes

    PNS contains

  • 53

    Armlike processes that extend from cell body

    Dendrites

  • 54

    Motor neurons can contain 100s of these short, tapering, diffusely branched processes –Contain same organelles as Soma

    Neuron Processes: Dendrites

  • 55

    Receptive (input) region of neuron •Convey incoming messages toward cell body as graded potentials (short distance signals) •In many brain areas, finer dendrites are highly specialized to collect information –Contain Dendritic Spines, appendages with bulbous or spiky ends

    Neuron Processes: Dendrites

  • 56

    can be short/absent; or comprises almost entire length of cell ●Can be over 1 meter long

    Neuron Processes: Axon

  • 57

    cone-shaped area at the start of the Axon

    Axon Hillock

  • 58

    long axons

    Nerve Fibers

  • 59

    occasional branches

    Axon Collaterals

  • 60

    branch profusely at their terminus ●Can number as many as 10,000 terminal branches

    Axon Terminals or Terminal Boutons

  • 61

    Functional Characteristics –Conducting region of Neuron –Generates nerve impulses & transmits them along Axolemma (cell membrane) to Axon Terminal

    Neuron Processes: Axon

  • 62

    secretes Neurotransmitters- released into extracellular space which can excite of inhibit neurons it contacts

    Terminal

  • 63

    rely on Soma to renew proteins & membranes

    Axons

  • 64

    have efficient internal transport mechanisms ●Molecules & organelles are moved along axons by motor proteins & cytoskeletal elements -Quickly decay if cut or damaged

    Neuron Processes: Axon

  • 65

    Neuron Processes: Axon Movement occurs in both directions

    Anterograde: away from cell body, Retrograde: toward cell body

  • 66

    away from cell body

    Anterograde

  • 67

    toward cell body

    Retrograde

  • 68

    Ex: mitochondria, cytoskeletal elements, membrane components, enzymes

    Anterograde

  • 69

    Ex: organelles to be degraded, signal molecules, viruses, & bacterial toxins

    Retrograde

  • 70

    Certain viruses & bacterial toxins damage neural tissues by using

    retrograde axonal transport

  • 71

    Ex: Poliomyelitis, Rabies, Herpes Simplex & Tetanus toxin

    Retrograde axonal transport

  • 72

    Viruses containing “corrected” genes or microRNA to suppress defective genes can enter cell through

    retrograde transport

  • 73

    Whitish, protein-lipid substance –Protect and electrically insulate axon –Increase speed of nerve impulse transmission

    Myelin Sheath

  • 74

    segmented sheath surrounds most long or large-diameter axons

    Myelinated Fibers

  • 75

    do not contain sheath –Conduct impulses more slowly

    Non-Myelinated Fibers

  • 76

    Formed by Schwann Cells –Wraps around axon in jelly roll fashion –One cell forms one segment of myelin sheath

    PNS Myelination

  • 77

    peripheral bulge containing nucleus & most of cytoplasm

    Outer Collar of Perinuclear Cytoplasm (Neurilemma):

  • 78

    Plasma membranes have less protein –No channels or carriers, so good electrical insulators –Interlocking proteins bind adjacent myelin membranes

    PNS Myelination

  • 79

    A Schwann cell envelops an axon.

    1

  • 80

    The Schwann cell then rotates around the axon, wrapping its plasma membrane loosely around it in successive layers.

    2

  • 81

    What is step 3

    The Schwann cell then rotates around the axon, wrapping its plasma membrane loosely around it in successive layers., Has Myelin sheath

  • 82

    Myelin sheath

    1

  • 83

    Outer collar of perinuclear cytoplasm (of Schwann cell)

    2

  • 84

    –Gaps between Schwann cells –Sites where axon collaterals can emerge ●Nodes of Ranvier

    Myelin Sheath Gaps

  • 85

    –Thin fibers not wrapped in Myelin; surrounded by Schwann Cells but no coiling; one cell may surround 15 different fibers

    Non-Myelinated fibers

  • 86

    Neuron Processes: CNS Myelination •Formed by processes of _______ not whole cells –Each cell can wrap up to 60 axons at once –Myelin sheath gap is present –No outer collar of perinuclear cytoplasm due to wide distribution

    Oligodendrocytes

  • 87

    are unmyelinated, but covered by long extensions of adjacent neuroglia

    Thinnest fibers

  • 88

    regions of brain & spinal cord with dense collections of myelinated fibers ●Usually fiber tracts

    White matter

  • 89

    mostly neuron cell bodies & non-myelinated fibers

    Gray matter

  • 90

    Structural Classification of Neurons: Multipolar

    3+ processes (1 axon, others dendrites)

  • 91

    Structural Classification of Neurons: Bipolar

    2 processes (1 axon, 1 dendrite) –Rare (ex: retina & olfactory mucosa)

  • 92

    Structural Classification of Neurons: Unipolar

    one T-like process (two axons) –Also called Pseudounipolar

  • 93

    Structural Classification of Neurons: (distal) process: associated with sensory receptor

    Peripheral

  • 94

    Structural Classification of Neurons: (central) process: enters CNS

    Proximal

  • 95

    Many processes extend from the cell body. All are dendrites except for a single axon.

    Multipolar

  • 96

    Two processes extend from the cell body. One is a fused dendrite, the other is an axon.

    Bipolar

  • 97

    One process extends from the cell body and forms central and peripheral processes, which together comprise an axon.

    Unipolar (Pseudounipolar)

  • 98

    MULTIPOLAR: Receptive region (receives stimulus).

    blue

  • 99

    MULTIPOLAR: Conducting region (generates/transmits action potential).

    green

  • 100

    MULTIPOLAR: Secretory region (axon terminals release neurotransmitters).

    red