The Nervous System Poudre High School By: Ben Kirk

The Nervous SystemThe Nervous System

Poudre High SchoolPoudre High School

By:By:

Ben KirkBen Kirk

FunctionsFunctions

Regulation of all body functionRegulation of all body function Sensory: Information receptionSensory: Information reception Response: Response transmission Response: Response transmission Integrate: Integrate and interpret all body Integrate: Integrate and interpret all body

changes/stimulichanges/stimuli

OrganizationOrganization

Central Nervous System (CNS): Brain Central Nervous System (CNS): Brain and Spinal Cordand Spinal Cord Control center for the entire nervous systemControl center for the entire nervous system Receives, processes, integrates and Receives, processes, integrates and

produces responses to all stimuliproduces responses to all stimuli Higher Functioning (the brain primarily): Higher Functioning (the brain primarily):

intelligence, memory, thought, emotion and intelligence, memory, thought, emotion and learninglearning

The Central Nervous SystemThe Central Nervous System

http://www.sruweb.com/~walsh/cns_pns.jpg


Peripheral Nervous System (PNS): All Peripheral Nervous System (PNS): All neural tissue outside the CNSneural tissue outside the CNS Delivery of sensory information from sensory Delivery of sensory information from sensory

glands/organs to the CNSglands/organs to the CNS Transmission of motor information from the Transmission of motor information from the

CNS to effectors glands/organsCNS to effectors glands/organs


Peripheral Nervous SystemPeripheral Nervous System Somatic Nervous System: VoluntarySomatic Nervous System: Voluntary

Controls voluntary muscle contractions (skeletal Controls voluntary muscle contractions (skeletal muscle)muscle)

Autonomic Nervous System: InvoluntaryAutonomic Nervous System: Involuntary Involuntary movements, processes and reflexesInvoluntary movements, processes and reflexes Visceral organs, cardiac muscle, smooth muscle Visceral organs, cardiac muscle, smooth muscle

and glands (heart rate, vessel diameter, and glands (heart rate, vessel diameter, digestion, etc…)digestion, etc…)


Autonomic Nervous SystemAutonomic Nervous System Sympathetic Nervous System: Expenditure of Sympathetic Nervous System: Expenditure of

energy energy Fight or FlightFight or Flight Increased Heart RateIncreased Heart Rate

Parasympathetic Nervous System: Restoration Parasympathetic Nervous System: Restoration and conservation of energyand conservation of energy

Rest and DigestRest and Digest Slows Heart RateSlows Heart Rate

http://www.sirinet.net/~jgjohnso/nervous.html

HistologyHistology

Neuroglia: Glial CellsNeuroglia: Glial Cells 6 Types of glia cells6 Types of glia cells Primary Function is to protect and support Primary Function is to protect and support

neuronsneurons Smaller and more numerous (5-10X) than Smaller and more numerous (5-10X) than

neuronsneurons Common source of tumors (Gliomas)Common source of tumors (Gliomas)

40-45% of all brain tumors40-45% of all brain tumors

HistologyHistology

Neurons: Conduct impulses from one part of Neurons: Conduct impulses from one part of the body to anotherthe body to another Cell Body (Soma):Cell Body (Soma):

Large, pronounced nucleusLarge, pronounced nucleus No myotic apparatus in cytoplasmNo myotic apparatus in cytoplasm

Neuron reproduction/regeneration is compromised Neuron reproduction/regeneration is compromised

Dendrites:Dendrites: Highly branched processes extending from cell bodyHighly branched processes extending from cell body Each neuron in the CNS has 10,000-100,000 dendrite Each neuron in the CNS has 10,000-100,000 dendrite

branches.branches. Each branch has 100,000-1million sensory inputs!!!Each branch has 100,000-1million sensory inputs!!!

HistologyHistology

Neurons:Neurons: Axon: Single thin extension that sends Axon: Single thin extension that sends

electrical impulses to other neurons or electrical impulses to other neurons or tissuestissues 1mm-1meter in length1mm-1meter in length Axon Terminal contains neurotransmitters that Axon Terminal contains neurotransmitters that

are released to trigger subsequent impulsesare released to trigger subsequent impulses

Axon Hillock: Where all electrical impulses Axon Hillock: Where all electrical impulses are summated to trigger an impulse, or not.are summated to trigger an impulse, or not.

The NeuronThe Neuron

HistologyHistology

Neuron:Neuron: Myelin (myelin sheath): Multiple layered, Myelin (myelin sheath): Multiple layered,

lipid and protein sheath covering neuron lipid and protein sheath covering neuron axons (not all axons are myelinated)axons (not all axons are myelinated) Electrically insulates axon and increases Electrically insulates axon and increases

conduction speed (Ex. Leaky garden hose)conduction speed (Ex. Leaky garden hose) Multiple Sclerosis: Autoimmune disease that Multiple Sclerosis: Autoimmune disease that

breaks down the myelin sheath in the CNS.breaks down the myelin sheath in the CNS. Tremors: Unregulated electrical impulsesTremors: Unregulated electrical impulses

HistologyHistology

Neurons:Neurons: Myelin:Myelin:

Myelin ProductionMyelin Production Schwann cells (PNS): Myelinate a single segment of a single Schwann cells (PNS): Myelinate a single segment of a single

axon.axon. Have limited ability to regenerate PNS neural tissueHave limited ability to regenerate PNS neural tissue

Oligodendrocyte (CNS): A single oligodendrocyte can Oligodendrocyte (CNS): A single oligodendrocyte can myelinate multiple segments of multiple axonsmyelinate multiple segments of multiple axons

CNS neuron regeneration is very complex and relatively CNS neuron regeneration is very complex and relatively nonexistent.nonexistent.

Myelination = White Myelination = White Unmyelinated = GrayUnmyelinated = Gray

Classification of NeuronsClassification of Neurons

Structural: Based on the # of processes Structural: Based on the # of processes extending from the cell bodyextending from the cell body Multipolar: many dendrites and one axonMultipolar: many dendrites and one axon

Most cells of the CNSMost cells of the CNS

Bipolar: One dendrite and one axonBipolar: One dendrite and one axon Retina of eye, inner ear and noseRetina of eye, inner ear and nose

Unipolar: Has one continuous branch with both an Unipolar: Has one continuous branch with both an axon and a dendrite (cell body off to side) axon and a dendrite (cell body off to side) Dorsal root ganglia (sensory cell bodies of spinal nerves)Dorsal root ganglia (sensory cell bodies of spinal nerves)

Classification of NeuronsClassification of Neurons

Functional: Based on the direction of impulse Functional: Based on the direction of impulse propagationpropagation Sensory (Afferent): Transmit impulses from Sensory (Afferent): Transmit impulses from

receptors in skin, muscles, sensory organs, joints, receptors in skin, muscles, sensory organs, joints, and viscera to the CNSand viscera to the CNS

Motor (Efferent): Transmit impulses from the CNS Motor (Efferent): Transmit impulses from the CNS to peripheral effectors (muscles and glands)to peripheral effectors (muscles and glands)

Interneuron (Association): Carry impulses from Interneuron (Association): Carry impulses from sensory neurons to motor neurons within the CNSsensory neurons to motor neurons within the CNS Make up the majority of human neuronsMake up the majority of human neurons

Grouping of Neural Grouping of Neural TissueTissue

Nerve FiberNerve Fiber: Any process projecting from a : Any process projecting from a cell bodycell body Axon or dendriteAxon or dendrite

NerveNerve: A group of many fibers within the PNS: A group of many fibers within the PNS Not a neuronNot a neuron Usually contain both sensory and motor nerve fibersUsually contain both sensory and motor nerve fibers sciatic nerve, ulnar nervesciatic nerve, ulnar nerve

GangliaGanglia: Group of cell bodies and synapses : Group of cell bodies and synapses within the PNS.within the PNS.


Tract: Bundle of fibers within the CNSTract: Bundle of fibers within the CNS May run long distances up or down the spinal May run long distances up or down the spinal

column or connecting parts of the braincolumn or connecting parts of the brain Ascending tracts carry information upward (sensory)Ascending tracts carry information upward (sensory) Descending tracts carry information downward Descending tracts carry information downward

(motor)(motor)

White Matter: Group of myelinated axons from White Matter: Group of myelinated axons from many neuronsmany neurons Look white due to myelinationLook white due to myelination


Gray Matter: Unmyelinated axons, Gray Matter: Unmyelinated axons, dendrites, or cell bodies within the CNSdendrites, or cell bodies within the CNS Found covering the outer surfaces and in the Found covering the outer surfaces and in the

deeper regions (nuclei) of the braindeeper regions (nuclei) of the brain Compose the “horns” of the spinal cordCompose the “horns” of the spinal cord

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The Nervous System Poudre High School By: Ben Kirk