The Nervous SystemThe Nervous System

I. The Nervous SystemI. The Nervous System

A. A. Two main divisionsTwo main divisions::1.1. The Central Nervous System The Central Nervous System

(CNS)(CNS)

2.2. The Peripheral Nervous The Peripheral Nervous System (PNS)System (PNS)

B. The CNSB. The CNS

1. Two main parts:1. Two main parts:• The BrainThe Brain: the main switch where : the main switch where

impulses originate and flow.impulses originate and flow.

• The Spinal CordThe Spinal Cord: the link between the : the link between the brain and the rest of the body.brain and the rest of the body.

C. The BrainC. The Brain

• 1. 1. MAJOR DIVISIONSMAJOR DIVISIONS– CerebrumCerebrum: part of the brain responsible for : part of the brain responsible for

all voluntary activities of the body.all voluntary activities of the body.• LobesLobes• FrontalFrontal• TemporalTemporal• ParietalParietal• OccipitalOccipital

– CerebellumCerebellum: part of the brain that : part of the brain that coordinates and balances the actions of coordinates and balances the actions of muscle.muscle.

– BrainstemBrainstem: structure that connects the brain : structure that connects the brain with the spinal cord. Coordinates and with the spinal cord. Coordinates and integrates all the information coming into integrates all the information coming into the brain.the brain.

C. The PNSC. The PNS

1. Two major divisions1. Two major divisions• SensorySensory: transmits impulses from : transmits impulses from

the sense organs to the CNS.the sense organs to the CNS.

• MotorMotor: transmits impulses from the : transmits impulses from the CNS to the muscle or glands.CNS to the muscle or glands.

D. Motor Divisions in the PNSD. Motor Divisions in the PNS

1.1. AutonomicAutonomic: regulates involuntary : regulates involuntary activities.activities.

a.a. SympatheticSympathetic nervous system nervous system: : stimulates fight-or-flight reactionsstimulates fight-or-flight reactions

b.b. ParasympatheticParasympathetic: stimulates calmer : stimulates calmer functions such as digestionfunctions such as digestion

2.2. SomaticSomatic: regulates activities under : regulates activities under conscious control such as muscle conscious control such as muscle movement and reflexes.movement and reflexes.

E. NeuronsE. Neurons

1.1. Cells that carry messages throughout the Cells that carry messages throughout the nervous system.nervous system.

2.2. TypesTypes• Sensory Neurons:Sensory Neurons: carry impulses from the sense carry impulses from the sense

organs to the brain and spinal cord.organs to the brain and spinal cord.• Motor Neurons:Motor Neurons: carry impulses from the brain carry impulses from the brain

and spinal cord to muscles or glands.and spinal cord to muscles or glands.• Interneurons:Interneurons: (association) connect sensory and (association) connect sensory and

motor neurons and carries impulses between motor neurons and carries impulses between them.them.

• 3. 3. Parts of a motor neuronParts of a motor neuron• cell bodycell body• NucleusNucleus• DendritesDendrites• AxonAxon• Myelin sheath (schwann cells)Myelin sheath (schwann cells)• Motor end plateMotor end plate• Motor end brushMotor end brush

nucleus

axon

myelin

Effector (muscle)

motor end plate

end brush

cell body{dendrite

cytoplasm

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F. Impulses moves along a neuronF. Impulses moves along a neuron

• Resting PotentialResting Potential: the difference in : the difference in charge across a nerve cell membrane charge across a nerve cell membrane resulting from the negative charge on resulting from the negative charge on the inside and the positive charge on the the inside and the positive charge on the outside = polarizedoutside = polarized

• ThresholdThreshold: A minimum level of a : A minimum level of a stimulus required to activate a neuron.stimulus required to activate a neuron.

• Action PotentialAction Potential: changes in membrane : changes in membrane potential that characterize a nerve impulse. potential that characterize a nerve impulse. the depolarization and repolarization of the the depolarization and repolarization of the membrane.membrane.

MyelinMyelin: substance composed of lipids and : substance composed of lipids and protein that forms an insulated sheath protein that forms an insulated sheath around an axon. It increases the rate of the around an axon. It increases the rate of the impulse.impulse.

a b c d e f g h

a. synapse

b. neurotransmitter

c. axon terminal

d. myelin

e. axon

f. cell body

g. dendrite

h. receptor

answers

Identify the parts of the neuronWhat direction does the impulse travel?

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G. Stimulation of a neuronG. Stimulation of a neuron

• ReceptorsReceptors: special sensory : special sensory neurons in sense organs that neurons in sense organs that receive stimuli from the external receive stimuli from the external environment.environment.

• EffectorsEffectors: muscle or glands that : muscle or glands that bring about a coordinated bring about a coordinated response.response.

• SynapsesSynapses: points of near contact which : points of near contact which impulses are chemically passed from impulses are chemically passed from one neuron to another.one neuron to another.

• NeurotransmittersNeurotransmitters: chemicals located : chemicals located within vesicles that are used by the within vesicles that are used by the neuron to signal another.neuron to signal another.– Example = acetyl choline, Example = acetyl choline,

H. Simple Reflex ArcH. Simple Reflex Arc

• Sensory neuronSensory neuron: neuron that carries : neuron that carries impulses from the sense organs to the impulses from the sense organs to the brain and/or spinal cord.brain and/or spinal cord.

• InterneuronInterneuron: (association) cell that : (association) cell that connects sensory and motor neurons connects sensory and motor neurons and carries impulses between them.and carries impulses between them.

• Motor neuronsMotor neurons: neuron that carries : neuron that carries impulses from the brain and/or spinal impulses from the brain and/or spinal cord to muscles and glands.cord to muscles and glands.

sensory neuron

cell body (sensory neuron)

receptors

synapse

synapse

motor neuron

effector (muscle)

association neuron

Label the diagram

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I. Diagnostic TechniquesI. Diagnostic Techniques

• A. MRI – magnetic resonance A. MRI – magnetic resonance imaging imaging– Page 25 in Unit 13 packetPage 25 in Unit 13 packet

• DiagramDiagram• Machine typesMachine types• Images – knee, brainImages – knee, brain• Image series of headImage series of head

– Images tissues and not bones or teethImages tissues and not bones or teeth

• B. CT – computed tomographyB. CT – computed tomography– Page 27 in Unit 13 packetPage 27 in Unit 13 packet

• MachineMachine• Images – kidneyImages – kidney

– Series of x-ray images, can produce 3-Series of x-ray images, can produce 3-d imagesd images

• C. SonogramC. Sonogram– Page 26 in Unit 13 packetPage 26 in Unit 13 packet– Uses ultra sound to image internal Uses ultra sound to image internal

organsorgans