ORGANIZATION OF THE ORGANIZATION OF THE NERVOUS SYSTEMNERVOUS SYSTEM

FUNCTIONSFUNCTIONS

SENSORYSENSORYMOTORMOTORCOGNITIVECOGNITIVE

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:BrainBrain

Spinal 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 System

May 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 Subdivisions

Sympathetic systemSympathetic system(fight or flight)(fight or flight)

Also called thoracolumbarAlso called thoracolumbarParasympathetic systemParasympathetic system

(feed and breed)(feed and breed)

Also called craniosacralAlso called craniosacral

Parts of a NeuronParts of a Neuron

Cell body:Cell body:Trophic unitTrophic unit

PerikaryonPerikaryonDendrites:Dendrites:

Receptive unitReceptive unitAxon:Axon:

Conductive unitConductive unit

Cell BodyCell Body

That 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 Organelles

NucleusNucleusGolgi apparatusGolgi apparatusRERRER

RibosomesRibosomes=Nissl substance=Nissl substance

DendritesDendrites

Branches 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.

AxonAxon

That 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)

AxonAxon

Ends 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.

AxonAxon

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

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

AxonAxon

Contains:Contains:MitochondriaMitochondria

NeurofilamentsNeurofilaments

NeurotubulesNeurotubules

Axonal TransportAxonal Transport

AnterogradeAnterogradeRetrogradeRetrogradeSlow transportSlow transportFast transportFast transport

AxonAxon

Covered 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 Terminology

Nucleus: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 Terminology

Nerve: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 Terminology

White 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 CNS

Refer to p. 63 in syllabusRefer to p. 63 in syllabus

Spinal Nerve BranchesSpinal Nerve Branches

Dorsal primary ramusDorsal primary ramusVentral primary ramusVentral primary ramusRamus recurrensRamus recurrensWhite ramus communicansWhite ramus communicansGray ramus communicansGray ramus communicans

Spinal Nerve BranchesSpinal Nerve Branches

Paravertebral ganglionParavertebral ganglionSplanchnic nerveSplanchnic nervePrevertebral ganglion Prevertebral ganglion

Reflex ArcReflex Arc

Afferent (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).

SynapseSynapse

Components: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.