Chapter 35 “The Chapter 35 “The Nervous SystemNervous System””

•35.1 “The Human 35.1 “The Human Nervous System”Nervous System”

• Objective:Objective:– List the 3 main structures of a List the 3 main structures of a

neuronneuron– Describe a Nerve ImpulseDescribe a Nerve Impulse

NeuronsNeurons• Basic unit of the N.S.Basic unit of the N.S.• Carry messages in the form of electrical Carry messages in the form of electrical

impulsesimpulses• Made up of:Made up of:

– cell bodycell body - largest part - largest part– dendritesdendrites - carry impulses toward the cell - carry impulses toward the cell

bodybody– axonaxon - carries impulse away from cell body - carries impulse away from cell body– axon terminalaxon terminal – sends impulse to next neuron – sends impulse to next neuron

Three Types of NeuronsThree Types of Neurons

1.1.SensorySensory : body to brain : body to brain

2.2.MotorMotor : brain to body : brain to body

3.3. InterneuronsInterneurons : connect : connect sensory & motor neurons sensory & motor neurons in brain and spinal cordin brain and spinal cord

Nerve ImpulseNerve Impulse

• Begins when a neuron is stimulated Begins when a neuron is stimulated by env. or another neuronby env. or another neuron

• Resting PotentialResting Potential: a neuron without : a neuron without an impulsean impulse– Inside of neuron is more negative than Inside of neuron is more negative than

outsideoutside• Action PotentialAction Potential: change in charge: change in charge

– Inside of neuron becomes more positive Inside of neuron becomes more positive

Inside is negativeInside is negative

Inside becomes positive

Domino effect passes Domino effect passes action potential down action potential down axonaxon

Inside returns to negative

Resting Potential

MyelinMyelin•MyelinMyelin

sheath: fatty sheath: fatty layer which layer which insulates insulates axonaxon

•Speeds up Speeds up impulseimpulse

SynapseSynapse

•SynapseSynapse: The space between : The space between the axon terminal of one the axon terminal of one neuron and the dendrites of neuron and the dendrites of the next neuron.the next neuron.

•Axon terminal Axon terminal releases releases neurotransmitters. neurotransmitters.

35.2 “35.2 “Organization of Organization of the N.Sthe N.S””

•Objective:Objective:–Distinguish between the Distinguish between the Central Nervous System & Central Nervous System & the Peripheral Nervous the Peripheral Nervous System.System.

The Central Nervous The Central Nervous SystemSystem

• BrainBrain

• Spinal CordSpinal Cord

The BrainThe Brain

• Four lobes, two halvesFour lobes, two halves

• Major regions:Major regions:– Cerebrum – conscious activity/thoughtCerebrum – conscious activity/thought– Cerebellum – coordinates movementCerebellum – coordinates movement– Brain stem – connect brain and spinal cord, Brain stem – connect brain and spinal cord,

controls many involuntary fxnscontrols many involuntary fxns– Thalamus – receives sensory messagesThalamus – receives sensory messages– Hypothalamus – controls primitive needs and Hypothalamus – controls primitive needs and

emotionsemotions

The BrainThe Brain

The Spinal CordThe Spinal Cord

• 31 pairs of nerves 31 pairs of nerves branch offbranch off

• Controls reflex arcControls reflex arc

Peripheral Nervous Peripheral Nervous SystemSystem• All nerves outside of All nerves outside of

brain and spinal cordbrain and spinal cord

• Sensory – receives Sensory – receives internal and external internal and external stumulistumuli

• Motor – controls muscles Motor – controls muscles and glandsand glands

• Motor DivisionMotor Division– Somatic NS – controls all voluntary activitySomatic NS – controls all voluntary activity– Autonomic NS – involuntary activityAutonomic NS – involuntary activity

• Sympathetic – controls body during times Sympathetic – controls body during times of stressof stress

– Ex - speeds up heart rateEx - speeds up heart rate

• Parasympathetic – controls body Parasympathetic – controls body normally, returns body to normal state normally, returns body to normal state after stressafter stress

– Ex – slows heart rateEx – slows heart rate

Peripheral Nervous Peripheral Nervous SystemSystem

N.S. Concept MapN.S. Concept Map

B ra in S p in a l C ord

C en tra l N S

S om atic

S ym p ath e tic P arasym p ath e tic

A u ton om ic

M otor S en sory

P erip h era l N S

N ervou s S ys tem

Chapter 35.3 Chapter 35.3 ““The SensesThe Senses””

•Objective:Objective:–List and discuss the 5 List and discuss the 5 senses.senses.

The Five SensesThe Five Senses

•Sight, Sound, Taste, Touch, Sight, Sound, Taste, Touch, SmellSmell

•There are 5 general categories There are 5 general categories of sense receptors.of sense receptors.– Pain receptorsPain receptors– Thermoreceptors - temperatureThermoreceptors - temperature– Mechanoreceptors – touch, soundMechanoreceptors – touch, sound– Chemoreceptors - chemicalsChemoreceptors - chemicals– Photoreceptors - lightPhotoreceptors - light

VisionVision•PhotoreceptoPhotorecepto

rs in retinars in retina–Rods – Rods – detect lightdetect light

–Cones – Cones – detect colordetect color

                                            

HearingHearing

• Acoustic Receptors: a special Acoustic Receptors: a special type of type of mechanoreceptormechanoreceptor..– Respond to sound (disturbance Respond to sound (disturbance

of air)of air)– Found in inner ear. Found in inner ear.

• Semicircular canals: fluid filled Semicircular canals: fluid filled tubes that help you maintain tubes that help you maintain your balanceyour balance

The EarThe Ear

Semicircular canals

Smell & TasteSmell & Taste

•ChemoreceptorsChemoreceptors–Respond to taste Respond to taste & smell & smell (chemical (chemical stimuli)stimuli)

•Found in tongue, Found in tongue, roof of mouth, roof of mouth, nasal cavity.nasal cavity.