ORGANIZATION OF THE NERVOUS SYSTEM

ORGANIZATION OF THE ORGANIZATION OF THE NERVOUS SYSTEMNERVOUS SYSTEM

FUNCTIONSFUNCTIONSSENSORYSENSORYMOTORMOTORCOGNITIVECOGNITIVE

ANATOMICAL ORGANIZATION of the ANATOMICAL ORGANIZATION of the NERVOUS SYSTEMNERVOUS SYSTEM

NervousSystem

CNS PNS ANS

BRAIN

SPINALCORD

CRANIALNERVES

SPINALNERVES

SYMPATHETIC

PARA-SYMPATHETIC

Central Nervous System (CNS)Central Nervous System (CNS)Unpaired, bilaterally symmetrical Unpaired, bilaterally symmetrical

structures extending along the longitudinal structures extending along the longitudinal axis of the midsagittal plane of the body.axis of the midsagittal plane of the body.

Structures arising directly from the neural Structures arising directly from the neural tube.tube.

Includes:Includes:BrainBrainSpinal cordSpinal cord

Peripheral Nervous SystemPeripheral Nervous System (PNS)(PNS)Made up of transmission pathways Made up of transmission pathways

carrying information between the CNS and carrying information between the CNS and external/internal environments.external/internal environments.

Afferent (sensory) pathways:Afferent (sensory) pathways:Carry information to the CNS.Carry information to the CNS.

Efferent (motor) pathways:Efferent (motor) pathways:Carry information from the CNS.Carry information from the CNS.

Peripheral Nervous SystemPeripheral Nervous System Includes:Includes:

Cranial nerves (12 pairs)Cranial nerves (12 pairs)Spinal nerves (31 pairs)Spinal nerves (31 pairs)

Also includes sensory receptors in skin Also includes sensory receptors in skin and wall of gut tube as well as in tendons and wall of gut tube as well as in tendons and skeletal muscles.and skeletal muscles.

Also includes motor end plates between Also includes motor end plates between motor neurons and skeletal muscle fibers.motor neurons and skeletal muscle fibers.

Autonomic Nervous SystemAutonomic Nervous SystemMay be considered a subdivision of the May be considered a subdivision of the

PNS.PNS.Entirely motor.Entirely motor. Innervates smooth muscle and glands Innervates smooth muscle and glands

(viscera)(viscera)

ANS SubdivisionsANS SubdivisionsSympathetic systemSympathetic system

(fight or flight)(fight or flight)Also called thoracolumbarAlso called thoracolumbar

Parasympathetic systemParasympathetic system(feed and breed)(feed and breed)Also called craniosacralAlso called craniosacral

Parts of a NeuronParts of a NeuronCell body:Cell body:

Trophic unitTrophic unitPerikaryonPerikaryon

Dendrites:Dendrites:Receptive unitReceptive unit

Axon:Axon:Conductive unitConductive unit

Cell BodyCell BodyThat part of a neuron that encloses That part of a neuron that encloses

the nucleus and other organelles the nucleus and other organelles necessary to maintain and repair necessary to maintain and repair neuron.neuron.

Cell Body OrganellesCell Body OrganellesNucleusNucleusGolgi apparatusGolgi apparatusRERRER

RibosomesRibosomes=Nissl substance=Nissl substance

DendritesDendritesBranches off the cell body that carry Branches off the cell body that carry

information to the cell body.information to the cell body.Usually several to many.Usually several to many.Relatively short.Relatively short.Often branched.Often branched.Have receptors for neurotransmitters.Have receptors for neurotransmitters.Conduct local potentials.Conduct local potentials.

AxonAxonThat part of the neuron that carries That part of the neuron that carries

information to another neuron or muscle information to another neuron or muscle cell.cell.

Usually relatively long.Usually relatively long.Single.Single.Conducts action potential (nerve impulse)Conducts action potential (nerve impulse)

AxonAxonEnds in short branched processes called:Ends in short branched processes called:

Telodendria:Telodendria:Give off endings called terminal boutons.Give off endings called terminal boutons.Terminal boutons contain synaptic vesicles Terminal boutons contain synaptic vesicles

of of neurotransmitters.neurotransmitters.May have collateral branches.May have collateral branches.

AxonAxonCell membrane is called the axolemma.Cell membrane is called the axolemma.

Cytoplasm is called the axoplasm.Cytoplasm is called the axoplasm.

AxonAxonContains:Contains:

MitochondriaMitochondriaNeurofilamentsNeurofilamentsNeurotubulesNeurotubules

Axonal TransportAxonal TransportAnterogradeAnterogradeRetrogradeRetrogradeSlow transportSlow transportFast transportFast transport

AxonAxonCovered by neurolemma:Covered by neurolemma:

Made up of Schwann cells.Made up of Schwann cells.Often myelinated:Often myelinated:

Myelin is formed by Schwann cells.Myelin is formed by Schwann cells.Note: axon is only part of neuron that is Note: axon is only part of neuron that is

ever myelinated.ever myelinated.

General TerminologyGeneral TerminologyNucleus:Nucleus:

Aggregation of dendrites and nerve cell Aggregation of dendrites and nerve cell bodies in the CNS.bodies in the CNS.

Ganglion:Ganglion:Aggregation of dendrites and nerve cell Aggregation of dendrites and nerve cell

bodies in the PNS.bodies in the PNS.

General TerminologyGeneral TerminologyNerve:Nerve:

Bundle of fibers (axons) in the PNS.Bundle of fibers (axons) in the PNS.Tract:Tract:

Bundle of fibers (axons) in the CNS.Bundle of fibers (axons) in the CNS.Commissure:Commissure:

Tract in the CNS that crosses from one Tract in the CNS that crosses from one side side to the other.to the other.

General TerminologyGeneral TerminologyWhite matter:White matter:

Areas of myelinated axons.Areas of myelinated axons.Gray matter:Gray matter:

Areas of unmyelinated axons, cell bodies, Areas of unmyelinated axons, cell bodies, and dendrites.and dendrites.

Functions of the CNSFunctions of the CNSRefer to p. 63 in syllabusRefer to p. 63 in syllabus

Spinal Nerve BranchesSpinal Nerve BranchesDorsal primary ramusDorsal primary ramusVentral primary ramusVentral primary ramusRamus recurrensRamus recurrensWhite ramus communicansWhite ramus communicansGray ramus communicansGray ramus communicans

Spinal Nerve BranchesSpinal Nerve BranchesParavertebral ganglionParavertebral ganglionSplanchnic nerveSplanchnic nervePrevertebral ganglion Prevertebral ganglion

Reflex ArcReflex ArcAfferent (sensory) pathways:Afferent (sensory) pathways:

Somatic.Somatic.Visceral (splanchnic).Visceral (splanchnic).

Efferent (motor) pathways:Efferent (motor) pathways:Somatic.Somatic.Visceral (splanchnic).Visceral (splanchnic).

Association neurons (interneurons).Association neurons (interneurons).

SynapseSynapseComponents:Components:

Presynaptic membrane:Presynaptic membrane:With synaptic vesicles filled with With synaptic vesicles filled with neurotransmitters.neurotransmitters.

Synaptic cleft:Synaptic cleft:Postsynaptic membrane:Postsynaptic membrane:

With receptors for neurotransmitters.With receptors for neurotransmitters.Monosynaptic pathways.Monosynaptic pathways.Polysynaptic pathways.Polysynaptic pathways.