Nervous SystemNervous System

Chapter 35

VocabularyVocabulary1.1. muscle tissuemuscle tissue2.2. epithelial tissueepithelial tissue3.3. connective tissueconnective tissue4.4. nervous tissuenervous tissue5.5. negative feedbacknegative feedback6.6. neuronneuron7.7. cell bodycell body8.8. dendritedendrite9.9. axonaxon10.10. myelin sheathmyelin sheath11.11. resting potential resting potential 12.12. action potentialaction potential13.13. synapsesynapse14.14. neurotransmitterneurotransmitter

15.15. central nervous systemcentral nervous system16.16. cerebrumcerebrum17.17. cerebellumcerebellum18.18. brain stembrain stem19.19. reflexreflex

I.I. How Nerve Cells CommunicateHow Nerve Cells CommunicateA.A. Nervous system = controls and coordinates functions Nervous system = controls and coordinates functions

throughout the body and responds to internal and external throughout the body and responds to internal and external stimulistimuli

B.B. NeuronsNeurons = cells that transmit electrical signals (impulses) = cells that transmit electrical signals (impulses)1.1. 3 types of neurons = sensory, interneurons, motor3 types of neurons = sensory, interneurons, motor2.2. Parts of neuronParts of neuron

a.a. cell bodycell body = contains nucleus and cytoplasm = contains nucleus and cytoplasmb.b. dendritesdendrites = branched extensions that receive stimuli = branched extensions that receive stimuli

from the environment or from other neurons, impulse from the environment or from other neurons, impulse goes toward the cell body goes toward the cell body

c.c. axonaxon = a long fiber that carries impulses away from = a long fiber that carries impulses away from the cell body, ends in axon terminals the cell body, ends in axon terminals

d.d. mylein sheathmylein sheath = insulating membrane around axon, = insulating membrane around axon, nodes (gaps) allow impulse to jumps from one to the nodes (gaps) allow impulse to jumps from one to the other increasing speed of impulseother increasing speed of impulse

DRAW Figure 35-5, pg 897DRAW Figure 35-5, pg 897

Neuron

axon terminals

myelin sheaths

axon

dendrites

cell body

nodes

C.C. Nerve ImpulseNerve Impulse1.1. Resting NeuronResting Neuron

a.a. electrical charge of neuron is from charged ionselectrical charge of neuron is from charged ions

b.b. At rest, At rest, outsideoutside of the cell has a of the cell has a net “+”chargenet “+”charge, and , and the the insideinside has a has a net “-” chargenet “-” charge. .

c.c. resting potentialresting potential = electrical charge difference of a = electrical charge difference of a neuron at rest btwn. the outside and inside is -70 mVoltsneuron at rest btwn. the outside and inside is -70 mVolts

d.d. “ “sodium-potassium pump” in membrane sodium-potassium pump” in membrane pumps Napumps Na++ ions out of the cell & K ions out of the cell & K++ into the into the cell by active transport (takes energy)cell by active transport (takes energy)

2.2. Moving ImpulseMoving Impulsea.a. an impulse begins when a neuron is stimulated an impulse begins when a neuron is stimulated

by another neuron or by the environment by another neuron or by the environment b.b. the gates within the sodium channels open, the gates within the sodium channels open,

allowing positively charged Naallowing positively charged Na++ ions to flow ions to flow inside the cell, inside temporarily becomes more inside the cell, inside temporarily becomes more “+” than the outside“+” than the outside

c.c. internal charge goes from -70 mVolts to +30 mVoltsinternal charge goes from -70 mVolts to +30 mVolts

+

+

_

_

_

+

+

_

d.d. action potentialaction potential = reversal of charges, from negative to positive, is = reversal of charges, from negative to positive, is called a nerve impulsecalled a nerve impulse

e.e. influx of sodium stimulates the opening of potassium pores and K+ influx of sodium stimulates the opening of potassium pores and K+ flows outflows out

f.f. Now all of the sodium is inside and the Now all of the sodium is inside and the potassium is potassium is outside outside

How does the cell go back to its original condition?How does the cell go back to its original condition?g.g. The sodium/potassium pump kicks in to restore the resting potential.The sodium/potassium pump kicks in to restore the resting potential.

DRAW Figure 35-7, pg 899DRAW Figure 35-7, pg 899

+

_

__+

+

+

_

_

_

_

+

+

h.h. The depolarization on one segment The depolarization on one segment starts a domino effect down the neuron.starts a domino effect down the neuron.

+

_

_

++

_+

_

Movement of an Action PotentialMovement of an Action Potential

3.3. ThresholdThresholda.a. thresholdthreshold = minimum level of a stimulus that = minimum level of a stimulus that

is required to activate a neuron is required to activate a neuron

b.b. All-or-none nerve impulse All-or-none nerve impulse a stimulus a stimulus stronger than the threshold produces an stronger than the threshold produces an impulse, a stimulus that is weaker than the impulse, a stimulus that is weaker than the threshold will produce no impulse threshold will produce no impulse

1)1) like a pushing over a row of dominoeslike a pushing over a row of dominoes

Vesicle

Axon

Axon terminal

Synaptic cleft

Neurotransmitter

Receptor

Dendrite of adjacent neuron

Direction of Impulse

How an How an Impulse Impulse Moves Moves Between Between Two Two NeuronsNeurons

D.D. SynapseSynapse 1.1. synapsesynapse = gap between the axon of one neuron and = gap between the axon of one neuron and

the dendrites or cell body of the next neuronthe dendrites or cell body of the next neuron

2.2. When the impulse reaches the end of the axon When the impulse reaches the end of the axon chemicals called chemicals called neurotransmittersneurotransmitters are released are released and carry the signal to the next neuron.and carry the signal to the next neuron.

3.3. Overall impulse pathway:Overall impulse pathway:

Electrical --> Chemical --> ElectricalElectrical --> Chemical --> Electrical

DRAW Figure 35-8, page 900DRAW Figure 35-8, page 900

II. DII. Divisions of Nervous Systemivisions of Nervous SystemA.A. Overall FunctionsOverall Functions

1.1. Sensory input – vision, hearing, balance, smell, Sensory input – vision, hearing, balance, smell, taste, and touchtaste, and touch

2.2. Motor output – muscle contraction and Motor output – muscle contraction and movementmovement

3.3. Memory and integration of informationMemory and integration of information

B.B. Central Nervous System (CNS)Central Nervous System (CNS)1.1. Relays messages, processes info, analyzes infoRelays messages, processes info, analyzes info

2.2. Consists of brain & spinal cordConsists of brain & spinal cord

QuickTime™ and aSorenson Video 3 decompressorare needed to see this picture.

C.C. BrainBrain

1.1. CerebrumCerebrum a.a. Largest region; folds and grooves increase surface Largest region; folds and grooves increase surface

areaarea

b.b. Controls Controls voluntary activities and all higher brain voluntary activities and all higher brain functions (intelligence, learning and judgment)functions (intelligence, learning and judgment)

c.c. Right and left hemispheres that are connected by Right and left hemispheres that are connected by corpus callosumcorpus callosum

CerebrumCorpus callosum

2.2. CerebellumCerebelluma.a. Center for balance and coordination of Center for balance and coordination of

voluntary muscle movements.voluntary muscle movements.

Cerebellum

3.3. Brain StemBrain Stema.a. Relays information between brain and spinal cordRelays information between brain and spinal cordb.b. Comprised of the Comprised of the ponspons and and medulla oblongatamedulla oblongatac.c. Work together to control breathing, heart rate, Work together to control breathing, heart rate,

blood pressure, digestion, and swallowing.blood pressure, digestion, and swallowing.

Pons

Medulla oblongata

4. Thalamusa. Relay station for all sensory input to the cerebrum.

5. Hypothalamusa. Homeostatic center that controls endocrine system

(hormones), body temperature, thirst, hunger, anger and fatigue

Hypothalamus

Thalamus

PonsPons

Pituitary glandPituitary gland

HypothalamusHypothalamus

CerebrumCerebrum

Medulla oblongataMedulla oblongata Spinal cordSpinal cord

CerebellumCerebellum

Pineal Pineal glandgland

ThalamusThalamus

DRAW Figure 35-9, pg 901

D.D. Spinal CordSpinal Cord1.1. 31 pairs of nerves branch out from the spinal cord31 pairs of nerves branch out from the spinal cord

2.2. FunctionsFunctionsa.a. Carries info to and from brain to bodyCarries info to and from brain to bodyb.b. Reflex centerReflex center

Spinal nerve

Central canalGray matter

White matter

Meninges

E. ReflexesE. Reflexes1.1. reflexesreflexes = = quick, automatic response to a quick, automatic response to a

stimulusstimulus

2.2. 5-part5-part reflex arc:reflex arc:a.a. SensorySensory receptorreceptor reacts to stimulus (heat on reacts to stimulus (heat on

finger)finger)b.b. Impulse is carried to the spinal cord by a Impulse is carried to the spinal cord by a

sensorysensory neuronneuronc.c. In the In the spinal cord,spinal cord, the impulse is transferred to a the impulse is transferred to a

motormotor neuronneurond.d. MotorMotor neuronneuron conducts a nerve impulse to an conducts a nerve impulse to an

effectoreffector (arm muscles) (arm muscles)e.e. EffectorEffector responds to the impulses by contracting responds to the impulses by contracting

(hand gets pulled away from the heat)(hand gets pulled away from the heat)

Reflexes:DRAW Fig. 35-11 pg 904

F.F. Peripheral Nervous System (PNS)Peripheral Nervous System (PNS)1.1. Sensory neurons Sensory neurons transmits impulses from sense organs to CNS transmits impulses from sense organs to CNS2.2. Interneurons Interneurons connect sensory and motor neurons in spinal cord connect sensory and motor neurons in spinal cord3.3. Motor neurons Motor neurons transmits impulses from CNS to the muscles or transmits impulses from CNS to the muscles or

glandsglands

a.a. SomaticSomatic NS (voluntary) responds to external NS (voluntary) responds to external stimulistimuli

1)1) Regulates activities that are under conscious control Regulates activities that are under conscious control (e.g. picking your nose)(e.g. picking your nose)

2)2) Some reflex controlSome reflex control

b.b. AutonomicAutonomic (involuntary) NS respond to internal (involuntary) NS respond to internal stimuli; two divisions:stimuli; two divisions:

1)1) Sympathetic - Sympathetic - ↑ ↑ energy consumption (increase HR)energy consumption (increase HR)

2)2) Parasympathetic - Parasympathetic - ↓ ↓ energy consumption (decrease energy consumption (decrease HR)HR)

3)3) Both help maintain homeostasis by having opposing Both help maintain homeostasis by having opposing effectseffects

which consists of

is divided into

that make up

which is divided into

Nervous System

Sensory nerves

Motor nerves

Autonomic nervous system

Somatic nervous system

Central nervous system

Peripheral nervous system

Sympathetic nervous system

Parasympathetic nervous system

G.G. Nervous System Graphic OrganizerNervous System Graphic Organizer

III.III. The SensesThe SensesA.A. 5 General Sensory Receptors:5 General Sensory Receptors: pain, thermo-, pain, thermo-,

mechano-, chemo- and photoreceptors.mechano-, chemo- and photoreceptors. Where do you think these different types of Where do you think these different types of

receptors are found and what is their receptors are found and what is their function?function?

Take YOUR OWN NOTES on 35-4 pg 906-909Take YOUR OWN NOTES on 35-4 pg 906-909B.B. VisionVision

C.C. Hearing and BalanceHearing and Balance

D.D. Smell and TasteSmell and Taste

E.E. TouchTouch

IV. Drugs IV. Drugs A.A. DrugDrug = any substance, other than food, that changes = any substance, other than food, that changes

the structure or function of the body the structure or function of the body 1.1. The most powerful drugs affect the nervous system The most powerful drugs affect the nervous system 2.2. AddictionAddiction = an uncontrollable dependence on a drug = an uncontrollable dependence on a drug 3.3. Drug abuseDrug abuse = can be defined as using any drug in a way that = can be defined as using any drug in a way that

most doctors would not approve most doctors would not approve

B.B. NarcoticsNarcotics1.1. narcotic = substance that blunt the senses decreasing painnarcotic = substance that blunt the senses decreasing pain2.2. ex: opium, morphine, codeine, heroinex: opium, morphine, codeine, heroin3.3. HeroinHeroin - increases release of dopamine, over-stimulation of - increases release of dopamine, over-stimulation of

neuronsneuronsa.a. Effects – intense rush, pleasure, decrease of heart rate Effects – intense rush, pleasure, decrease of heart rate

and breathing, decrease painand breathing, decrease painb.b. Problems – receptors become used to this over-stimulation Problems – receptors become used to this over-stimulation

and need more heroin just to work normally (rapid and need more heroin just to work normally (rapid addiction), overdose causes breathing to stop addiction), overdose causes breathing to stop

C.C. StimulantsStimulants 1.1. stimulant = substance that increases heart rate, stimulant = substance that increases heart rate,

blood pressure, and breathing rateblood pressure, and breathing ratea.a. Increases the release of neurotransmitters; leads to Increases the release of neurotransmitters; leads to

release of energy and feeling of well-being, relieves release of energy and feeling of well-being, relieves painpain

b.b. When effect wears off, brain’s supply is depleted When effect wears off, brain’s supply is depleted leaving the user depressed and fatiguedleaving the user depressed and fatigued

c.c. Ex: cocaine, amphetamines (crystal meth, speed, ice, Ex: cocaine, amphetamines (crystal meth, speed, ice, crank), ecstasy, ritalin, nicotine, and caffeinecrank), ecstasy, ritalin, nicotine, and caffeine

2.2. Cocaine/crackCocaine/crack – blocks dopamine reuptake by – blocks dopamine reuptake by neurons causing a “flood” of dopamine in the brainneurons causing a “flood” of dopamine in the brain

a.a. Effects – euphoria and relaxationEffects – euphoria and relaxation

b.b. Problems – highly addictive, heart attacks, Problems – highly addictive, heart attacks, delirium, strokes, hypertensiondelirium, strokes, hypertension

In the synapse, or space between neurons (area of detail), cocaine binds to dopamine reuptake transporters, causing a "flood" of dopamine in the brain.

Cocaine and Your Brain

Cocaine

3.3. Meth / Speed Meth / Speed - damages axon terminals- damages axon terminalsa.a. Effects Effects –– temporary mood elevation, exhilaration temporary mood elevation, exhilaration

(high), increased mental alertness, wakefulness(high), increased mental alertness, wakefulnessb.b. Problems -- extremely addictive (sometimes with just Problems -- extremely addictive (sometimes with just

one use), very jittery high, along with anxiety, one use), very jittery high, along with anxiety, insomnia, sometimes paranoiainsomnia, sometimes paranoia, , can cause can cause convulsions, heart irregularities, high blood pressure, convulsions, heart irregularities, high blood pressure, depression, restlessness, tremors, severe fatigue, depression, restlessness, tremors, severe fatigue, overdose can cause coma and deathoverdose can cause coma and death

4.4. Ecstasy - Ecstasy - damages axon terminalsdamages axon terminals3.3. Effects – damages axon terminals, increased Effects – damages axon terminals, increased

energy, peacefulnessenergy, peacefulness4.4. Problems – teeth clenching, water regulation, Problems – teeth clenching, water regulation,

increased heart rate and blood pressure, heart, liver, increased heart rate and blood pressure, heart, liver, or kidney failure, permanently damages axon or kidney failure, permanently damages axon terminals affecting mood, sleep, and memoryterminals affecting mood, sleep, and memory

Serotonin travels through the healthy brain across the synapse. Ecstasy use damages the axon terminals (ends) of neuron fibers. Chemical messages relating to mood, sleep, memory, and more are disrupted.

ECSTASYECSTASY

D.D. DepressantsDepressants – suppresses CNS actions – suppresses CNS actions1.1. Effects – relieve anxiety, irritability, tension, produce a Effects – relieve anxiety, irritability, tension, produce a

state of intoxication   state of intoxication   2.2. Ex: tranquilizers, barbiturates, marijuana, alcoholEx: tranquilizers, barbiturates, marijuana, alcohol3.3. MarijuanaMarijuana

a.a. THC disrupts coordination of nerve impulses in the brainTHC disrupts coordination of nerve impulses in the brainb.b. long term – more lung damage than cigarettes, memory loss, long term – more lung damage than cigarettes, memory loss,

attention deficit, decreased levels of testosterone, abnormal attention deficit, decreased levels of testosterone, abnormal spermsperm

4.4. AlcoholAlcohola.a. blocks receptors making the neuron less excitable & blocks receptors making the neuron less excitable &

increases dopamineincreases dopamineb.b. physical and mental impairment, depression, liver damagephysical and mental impairment, depression, liver damagec.c. destroys liver cellsdestroys liver cellsd.d. involved in 1/3 of all automobile crashes, involved in 1/3 of all involved in 1/3 of all automobile crashes, involved in 1/3 of all

homicideshomicides

E.E. InhalantsInhalants – decreases O – decreases O22 to the brain, to the brain, poisons bodypoisons body

1.1. Effects – Effects – makes you feel light-headed or dizzy for makes you feel light-headed or dizzy for several minutes several minutes

2.2. Problems – death can result from 1st time, kidney Problems – death can result from 1st time, kidney and liver damage, decreased muscle size, loss of and liver damage, decreased muscle size, loss of smell an hearing over time, brain damagesmell an hearing over time, brain damage

3.3. Ex: glue, gasoline, nail polish remover, aerosolsEx: glue, gasoline, nail polish remover, aerosols

Cheap high, quick buzzYou can die the first time you try inhalants.Sudden Sniffing Death – sudden heart failure

Asphixiation (lack of O2)Inhalants damage or destroy myelin.

Healthy myelin helps speed messages from cell to cell in your brain. When myelin is damaged, your muscles won't be able to obey your brain.

Inhalants