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Anatomy and Physiology 203 > Chapter 11 pt 1) Fundamentals of Nervous System > Flashcards

Chapter 11 pt 1) Fundamentals of Nervous System Flashcards

1
Q

The Nervous System (Overview and Functions)

A
  • Master control of the body
  • Communicate via Electrical and Chemical Signals
    • Signals are Rapid and Specific
    • Response is usually immediate
  • Three Functions of Nervous system
    1. Sensory Input) Gather information and through sensory receptores (affrent pathway)
    2. Integration) Processing and interpretation of sensory input (Control center)
    3. Motor Output) Activation of effector organs (muscles/glands). Produces a response. (effrent pathway).
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2
Q

Two Divisions of the Nervous System

A
  • CNS) Central Nervous System
    • Brain and Spinal cord
    • Inegration and Control Center. Determines motor output
  • Prepherial Nervous System
    • Any nervous tissue ouside of CNS
    • Consists of nerves that extend from the brain and spinal chord
      • Spinal nerve) connects to spine
      • Cranial nerve) connects to brain.
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3
Q

Prepherial Nervous System (Two Divisions)

A
  • Sensory (Afferent) Division
    • Somatic sensory fibers) convay inpulses from skin, muscles, and joints to CNS.
    • Viseral Sensory Fibers) Convay Impules from visceral (internal) organs.
  • Motor (Efferent) Division
    • Transmits Impules from CNS to motor nuerons.
    • Two divisions) Somatic and Autonomic
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4
Q

Somatic Nervous System

A
  • Nerve Fibers conduct impules from CNS to skeletal muscles
  • Called the Voluntary Nervous System
    • Concious Control of Skeletal Muscles.
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5
Q

Autonomic Nervous System

A
  • Visceral Motor Nerve Fibers
  • Regulates smooth muscles, cardiac muscles, and glands
  • Called the Involuntary Nervous system
  • Two divisions
    • Sympathetic) Fight Or Flight System
    • Parasympathetic) Rest and Digest System.
    • Two systems work oppiosite to eachother
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6
Q

Histology of Nervous Tissue

A
  • Nuerons) Excitible cells that transmit signals
  • Nurogalieal cells) Support, protect and insulate Nuerons
    • Four main types in CNS
      • Astrocytes
      • Microglial Cells
      • Ependymal Cells
      • Oligodendrocytes
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7
Q

Astrocytes

A
  • Most abundant, versitile, and highly branched galial ce;;s/
  • Cling to nuerons, synaptic endings, and capaliries
  • Many functions which include
    • Support and Bracing of Nuerons
    • Exchanges between capaleries and nuerons
    • Guide Migration of Young Nuerons
    • Control enviornment around nuerons
    • Respomd to nerve impules and nuerotransmiters
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8
Q

Microgalial cells

A
  • Small, Ovoid Cells with thorny processes that touch and moniter nuerons.
  • Migrate toward injured nuerons and can transform and phagocytize (remove) microrganisms and nueronal debris.
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9
Q

Epedymal cells

A
  • Line fluid filled cavities in CNS and provide a barrier between cerebrospinal fluid and other fluid
  • Can be columnar or squamous, some are cilliated
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10
Q

Oligodendrocytes

A
  • Form thick Myelin Sheaths which insulare nerve fibers.
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11
Q

Nueroglia In PNS

A
  • Sataleite Cells) Surround nueron cell bodies in PNS
    • Similar function to Astrocytes
  • Schwann Cells) Completely surround prepherial nerve fibers and form mylin sheaths
    • Similar function to oligodendrocytes
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12
Q

Nuerons

A
  • Structural Units of nervous system
  • Last for a persons entire lifspan without dividing. (olfactory eptheliam does)
  • All have a Cell body and one or more processes
    *
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13
Q

Cell Body (Perikaryon or Soma)

A
  • Biosynthetic Center
    • Synthesises Protiens, Membranes, And Chemicals
    • Done in Rough ER (Also called Nissil Bodies)
  • Most are located in CNS
    • Nuclei) Clusters of nueron cell bodies in CNA
    • Ganglia) Clusters of Nueron Bodies in PNS
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14
Q

Nueron Processes

A
  • Extend from the body of the nerve
    • CNS) Contains cell bodies and processes
    • PNS) mostly cell processes
  • Tracts) Bundels of nueron processes in the CNS
  • Nerves) Bundles of nueron processes in the PNS
  • Two types
    • Axons and Dendrites
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15
Q

Dendrites

A
  • Short, tapering, branched processes
    • Contain same organelles as cell body
  • Recive (input) regoin of the nueron
    • Never goes out
    • Convay messages to cell body as Graded Potential
  • Contain Dendric spines
    • bulbous or spiky
    • point of contact (synapse) with other nueron.
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16
Q

The Axon (Structure)

A
  • Only one per nueron. Attached to cone shaped area called Axon Hitchcock.
  • Axon can be short or almost the entire length of the cell
    • Some over 1 meter long
  • Occasionally branched at a place called axon collaterals.
  • At the ends of axons there are thousands of branches
    • These brances are called Axon Terminals
17
Q

Axon (Funtions and Charcteristics)

A
  • Conduction region of nueron
  • Nuerons generate nerve impules and then transmit them along the cell membrane (axolemma) to Axon Terminal.
    • Terminal) place that secretes nurotransmitters
    • Nuerotransmiters excite or inhibit nuerons
  • Lack Golgi apperatus and ER
18
Q

Transport On the Axon (2 ways)

A
  • Molecules and Organelles are moved along axons by motor protiens in two directions
  • Anterograde) away from the cell body
    • EX) Midochondria, Cytoskeletal elements, membrane componants, enzymes.
  • Retrograde) Toward Cell body
    • EX) organelles that need to be destroyed, signal molecules, viruses, and toxins (to be destroyed)
19
Q

Myelin Sheath

A
  • Myelin) protien-lipid substance that protects and electrically insulates the axon.
    • Increases nerve tansmission speed
  • Mylinated Fibers) Most long or large diamater Axons
  • Nonmylinated Fibers) conduct impules more slowly.
20
Q

Mylenation in PNS

A
  • Function of Schwarnn cells
    • Cell coils around Axon and wraps itself tight
    • Outer collar of Perinuclar Cytoplasm contains nucleus
  • No protien channels or carriers so they are good at electrical insulation.
  • Signal Jumps on Nodes of Ravier (gaps between adjacent Schwann cells)
21
Q

Myelination in CNS

A
  • Formed by Oligodendrocytes but not the whole cell
    • Each cell can wrap 60 axons at once
    • Myelin sheath gap is present
22
Q

Structural Classification of Nuerons (3 types)

A
  • Multipolar) Have three or more processes (one axon)
    • Most common; major in CNS
  • Bipolar) 2 processes, 1 axon and one dendrite
    • Rare, (Retina and Olfactory Mucosa)
  • Unipolar) 1 short T like process, 2 axons
    • Also called psuedounipolar
  • Prepherial Process) Associated with Sensory Receptor
  • Central Process) Enter the CNS
    • Found in Ganglia.
23
Q

Functional Classification of Nuerons

A
  • Sensory (afferent) Transmit impulses from sensory receptors to CNS
  • Motor (Efferent) Carry impulses from CNS to effectors.
    • Multipolar. Most cell bodies are located in CNS
  • Internuerons) Association Nuerons
    • Between sensory and motor nuerons
    • Shuttle signals through the CNS pathway. Most are in CNS
    • 99% of the bodies nuerons are internuerons.
24
Q

Membrane Potentials

A
  • Nuerons have a resting membrane potential that they can rapidly change
  • Nerves respond to stimilus by creating an action potential (nerve impulse).
    • Impulse is the same regardless of the channel it came through.
25
Q

Roles of Membrane Ion Channels

A
  • Leakage (nongated) channels) Always open
  • Gated Channels) Protien changes shape to open
    • When channels are open ions diffuse quicky across membrane.
    • Diffuse doen chemical and electrical gradients. (electrochemical gradient)
  • Three types
    • Chemically Gated) Open when chemical binds
    • Voltage Gated) Open in response to changes in membrane potential
    • Mechanically Gated) open in close in response to receptors.
26
Q

Resting Membrane Potential

A
  • Of a resting nueron) -70mV
    • cytoplamsic side is slightly negative
    • actual voltage varries from -40 to -90 mV
  • Membrane is said to be polarized
  • Potential is made by
    • Diffrences in ionic compisition of ECF and ICF
    • Diffrences in plasma membrane permabiltiy.
27
Q

Diffrences in Ionic Compisition

A
  • ECF) has more Na+ than ICF
    • Balanced by clorine ions (Cl-)
  • ICF has higher concentration of K+ than ECF
    • Balanced by negativly charged protiens.
  • K+ plays the most improtant role in RMP
28
Q

Diffrences in Membrane Permiability

A
  • Impermiable to large, anionic protiens.
  • Slightly Permiable to Na+
    • Sodium diffuses into cell down concentration gradient
  • Membrane is 25 times more permiable to K+ than sodium
    • Potassium diffuses out of cell
  • Permiable to Cl-
  • More potassium diffused out than sodium goes in
    • As a result the inside of the cell is more negavitve
    • This charge makes RMP
  • Sodium Potassium Pump
    • Mantains concentration gradient of Na+ and K+
    • Three Na+ pumped out and two K+ pumped in
29
Q

Changing Membrane Potential

A
  • Membrane Potential Changes when
    • Ion concentration changes
    • Membrane permiabilty to ions change
  • Changes produce two signals
    • Graded Potential) short distance signals
    • Action Potential) long-distance axons
  • Changes in RMP send, inegrate, and recive information.
  • Changes in membrane potential are relative to RMP
    • Deplorization) decrese in membrane potential
      • Inside is less negative
      • Impulse probability increases
    • Hyperpolarization) Increase in membrane potential
      • Inside is more negative
      • Impule probability decreses.
30
Q

Action Potential

A
  • Long distance signal sending
  • Occurs in mucle cells and Axons of nuerons
  • Breif reversal of membrane potential with change in voltage. Carries signal long way
  • Also refered to as a Nerve Impulse.
31
Q

Four Steps of Action Potential

A
  1. Resting State) All Na+ and K+ channels are closed
    • Only leakage channels are open.
    • Na+ channels have two voltage sensitive gates
      • Activation gates) closed at rest
      • Inactivation gates) open at rest, channel is blocked so Na+ can’t enter
    • K+ channel is closed at rrst
  2. Deplorization) Na+ channels open
    • Na+ rushes in and gates open
    • Eventually all channels open (at -55 to -50 mv) and ICF is less negative.
  3. Repolarization) Na+ channels inactivate and K+ channels open
    • K+ exits cell down concentration graident
  4. Hyperpolarization) Some K+ channels remain open
    • Inside of membrane becomes more nagative
    • causes slight hyperpolarization
  • Once channels close Na+/K+ pumps restore orginal balance.
32
Q

Graded Potentials

A
  • Short Lived, Local messages that can die off
    • Stronger the stimulus, the more voltage changes and the further the current flows.
  • Trigegred by the stimulius that opens gated ion channels.
    • Once channel opens, deplorization spread
      *

Anatomy and Physiology 203 (43 decks)

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