QQ: What is the most : What is the most complexcomplex entityentity in the known in the known universeuniverse??

AA: : The human brainThe human brain The human brain consists of about The human brain consists of about

100 billion nerve cells! 100 billion nerve cells! A given neuron may have several A given neuron may have several

thousand connections; therefore, thousand connections; therefore, the human brain has at least the human brain has at least 100,000,000,000,000100,000,000,000,000 web-like web-like connections. connections. WOW!WOW!

One hundred trillion connections One hundred trillion connections is larger than the total number of is larger than the total number of atomic particles that make up the atomic particles that make up the known universe (Thompson, 3).known universe (Thompson, 3).

Biology and BehaviorBiology and BehaviorThe Nervous SystemThe Nervous System – – All living organisms have a nervous All living organisms have a nervous

system.system. The nervous system varies depending on The nervous system varies depending on

the species.the species. The human nervous system is the most The human nervous system is the most

complex of all species.complex of all species. The human nervous system is involved in The human nervous system is involved in

thinking, dreaming, feeling, moving, and thinking, dreaming, feeling, moving, and everything that makes you … everything that makes you … wellwell youyou!!

The nervous system also regulates all our The nervous system also regulates all our internal functions.internal functions.

1.1. DivisionDivision – – The nervous system is divided into two The nervous system is divided into two

main parts: main parts: The Central Nervous System (CNS)The Central Nervous System (CNS) The Peripheral Nervous System (PNS)The Peripheral Nervous System (PNS)

The Central Nervous SystemThe Central Nervous System The central nervous system consists of the The central nervous system consists of the brainbrain

and the and the spinal cordspinal cord.. The spinal cord extends from the brain and down The spinal cord extends from the brain and down

the back.the back. The spinal cord is a bundle of neurons about as The spinal cord is a bundle of neurons about as

thick as an adultthick as an adult’’s thumb.s thumb. The spinal cords function is to transmit messages The spinal cords function is to transmit messages

between the brain and the muscles, organs, and between the brain and the muscles, organs, and glands through the body.glands through the body.

The spinal cord is also involved in spinal reflexes.The spinal cord is also involved in spinal reflexes. A A spinal reflexspinal reflex is a simple, automatic response is a simple, automatic response

to a sudden stimulus – where the sensory to a sudden stimulus – where the sensory receptor is stimulated and the message is sent to receptor is stimulated and the message is sent to the spinal cord only and a response is sent the spinal cord only and a response is sent immediately from the spinal cord to the immediately from the spinal cord to the extremity.extremity.

The Peripheral Nervous The Peripheral Nervous SystemSystem

The peripheral nervous system is made up The peripheral nervous system is made up of all the neurons that send messages to of all the neurons that send messages to the central nervous system from all parts of the central nervous system from all parts of the body.the body.

The peripheral nervous system is divided The peripheral nervous system is divided into two parts:into two parts:

a)a) The The Somatic Nervous SystemSomatic Nervous System

b)b) The The Autonomic Nervous SystemAutonomic Nervous System

Organization of the Organization of the Nervous SystemNervous System

Nervous System

Central NS

Peripheral

Somatic AutonomicBrainSpinal

Cord

Sympathetic Parasympathetic

Divisions of the Nervous Divisions of the Nervous SystemSystem

The Somatic Nervous The Somatic Nervous SystemSystem

The The somatic nervous systemsomatic nervous system transmits sensory transmits sensory messages to/from the central nervous system.messages to/from the central nervous system.

The The somatic nervous systemsomatic nervous system is activated by touch, is activated by touch, pain, change in temperature, and changes in body pain, change in temperature, and changes in body position, as well as muscular movement.position, as well as muscular movement.

The The somatic nervous systemsomatic nervous system allows us to experience allows us to experience the sensations of hot and cold, and to feel pain and the sensations of hot and cold, and to feel pain and pressure.pressure.

The The somatic nervous systemsomatic nervous system sends messages to the sends messages to the muscles and glands and helps us maintain posture muscles and glands and helps us maintain posture and balance.and balance.

The Autonomic Nervous The Autonomic Nervous SystemSystem

The The ““autonomicautonomic”” means means ““occurring occurring involuntarilyinvoluntarily”” or automatically. or automatically.

The autonomic nervous system regulates The autonomic nervous system regulates the bodythe body’’s vital functions, such as s vital functions, such as heartbeat, breathing, digestion, and blood heartbeat, breathing, digestion, and blood pressure.pressure.

The autonomic nervous system is involved The autonomic nervous system is involved in the experience of emotion.in the experience of emotion.

The Autonomic Nervous System The Autonomic Nervous System (continued)(continued)

The autonomic nervous system is divided into two The autonomic nervous system is divided into two parts:parts:– a) a) the the sympatheticsympathetic – b) b) the the parasympatheticparasympathetic

These two parts work in opposition.These two parts work in opposition. The The sympatheticsympathetic is activated when a person is is activated when a person is

going into action, perhaps because of some going into action, perhaps because of some stressful situation.stressful situation.

The The sympathetic nervous systemsympathetic nervous system prepares the prepares the body either to confront the situation or to run body either to confront the situation or to run away. This is called the away. This is called the ““flight or fightflight or fight”” response response..– ExampleExample: : Attacked by a large angry dog – The sympathetic Attacked by a large angry dog – The sympathetic

nervous system suppresses digestion, increases the heart and nervous system suppresses digestion, increases the heart and respiration rates, and elevates the blood pressure, preparing respiration rates, and elevates the blood pressure, preparing the body to deal with the situation (run or fight).the body to deal with the situation (run or fight).

The The parasympathetic nervous systemparasympathetic nervous system restores the bodyrestores the body’’s reserves of energy to s reserves of energy to normal normal levelslevels, after an action has occurred., after an action has occurred.

Sympathetic Nervous Sympathetic Nervous SystemSystem

*Flight or Fight Response*Flight or Fight Response*Automatically accelerates heart rate, breathing, dilates pupils, slows down digestion.*Automatically accelerates heart rate, breathing, dilates pupils, slows down digestion.

Parasympathetic Nervous Parasympathetic Nervous SystemSystem

Automatically Automatically slows the body slows the body down after a down after a stressful event.stressful event.

Heart rate and Heart rate and breathing slow breathing slow down, pupils down, pupils constrict and constrict and digestion speeds digestion speeds up.up.

Neural and Hormonal Neural and Hormonal SystemsSystems

Will Explain Why We FEEL……

Pain

Strong

Sick

Nervous

It all Starts with the NeuronIt all Starts with the Neuron

The Neuron = Nerve CellThe Neuron = Nerve Cell

Neurons run through our entire bodies Neurons run through our entire bodies and communicate with each other.and communicate with each other.

Each person has approx. 100 billion Each person has approx. 100 billion neurons, most of which are found in the neurons, most of which are found in the brain.brain.

There are three basic types of neurons:There are three basic types of neurons:1.1. Motor neuronsMotor neurons

2.2. Sensory neuronsSensory neurons

3.3. InterneuronsInterneurons

Sensory NeuronsSensory Neurons(Afferent Neurons)(Afferent Neurons)

Take information from the Take information from the senses to the brain.senses to the brain.

Motor NeuronsMotor Neurons(Efferent Neurons)(Efferent Neurons)

Take information from brain Take information from brain to the rest of the body.to the rest of the body.

Inter NeuronsInter NeuronsTake messages Take messages

from Sensory from Sensory Neurons to Neurons to other parts of other parts of the brain or to the brain or to Motor Motor Neurons.Neurons.

Neural Anatomy & PhysiologyNeural Anatomy & Physiology Every neuron consists of: a Every neuron consists of: a cell bodycell body ( (somasoma), ),

dendritesdendrites, and an , and an axonaxon with with axon terminalsaxon terminals

Neural Anatomy & PhysiologyNeural Anatomy & PhysiologySynapseSynapse

Neurotransmitters (chemicals held in terminal buttons that travel through synaptic gap)

Neural Anatomy & Physiology Neural Anatomy & Physiology (continued)(continued)

TheThe cell body (soma)cell body (soma) produces energy produces energy that fuels the activity of the cell.that fuels the activity of the cell.

DendritesDendrites are thin fibers which branch are thin fibers which branch out from the cell body.out from the cell body. DendritesDendrites receive information from other receive information from other

neurons and pass the message through the cell neurons and pass the message through the cell body.body.

TheThe axonaxon carries messages away from the carries messages away from the cell body and towards the axon terminals.cell body and towards the axon terminals. A neuron has many dendrites but only one A neuron has many dendrites but only one

axon. Axons vary greatly in length.axon. Axons vary greatly in length.

Neural CommunicationNeural Communication

NeuronsNeurons The building blocks are The building blocks are neuronsneurons (i.e., (i.e., nerve cellsnerve cells).). Each neuron consists of a Each neuron consists of a cell bodycell body ( (somasoma) and its ) and its

branching fibers, called branching fibers, called dendritesdendrites.. The information is passed from The information is passed from somasoma to the to the axonaxon down down

to the to the axon terminalsaxon terminals across the across the synaptic cleftsynaptic cleft to other to other neurons or to muscles or glands.neurons or to muscles or glands.

A layer of fatty tissue, called A layer of fatty tissue, called myelin sheathmyelin sheath, insulates , insulates the axons of some neurons and helps speed the the axons of some neurons and helps speed the electrical transmission (impulse).electrical transmission (impulse). Evidence of myelin sheathEvidence of myelin sheath’’s importance appears in s importance appears in

multiple sclerosis – a disease in which myelin sheath multiple sclerosis – a disease in which myelin sheath degenerates.degenerates.

Depending on the type of neuron, the neural impulse Depending on the type of neuron, the neural impulse (electrical impulse) travels at speeds ranging from a (electrical impulse) travels at speeds ranging from a sluggish 2 miles per hour to 200 or more miles per hour.sluggish 2 miles per hour to 200 or more miles per hour.

Candy NeuronCandy Neuron

* Cell Body (Soma) – Marshmellow (1)* Dendrites – Pretzels (6)* Axon – Twizzler (1) * Terminal Branches – Mike And Ikes (6)* Terminal Buttons - M&Ms (6)

Directions: Label AND Define each part of your neuron – then snap a picture of your completed neuron and upload this picture to Edmodo.

*For 2 extra credit points, upload a picture of YOU with your candy neuron to Edmodo! Candy Neuron Selfie!!!

Neural CommunicationNeural Communication

The fluid interior of a resting axon has anThe fluid interior of a resting axon has an excess of negatively charged ions, while the excess of negatively charged ions, while the fluid outside the axon membrane has morefluid outside the axon membrane has more positively charged ions.positively charged ions. This positive outside / negative inside polarization This positive outside / negative inside polarization

is called the is called the RESTING POTENTIALRESTING POTENTIAL. . Neurons at rest have a slightly negative chargeNeurons at rest have a slightly negative charge Neuron firing is an Neuron firing is an electrochemical processelectrochemical process *electrical inside the neuron*electrical inside the neuron *chemical outside the neuron (in the synapse in *chemical outside the neuron (in the synapse in

thethe form of neurotransmitters)form of neurotransmitters)

Neural CommunicationNeural Communication

A neuron fires an impulse when it receives A neuron fires an impulse when it receives signals from sense receptors stimulated by signals from sense receptors stimulated by pressure, heat, light, or a chemical message from pressure, heat, light, or a chemical message from

adjacent neurons.adjacent neurons. This impulse is called the This impulse is called the ACTION POTENTIALACTION POTENTIAL – –

it is a brief electrical charge that travels down the it is a brief electrical charge that travels down the interior of the axon, like a line of dominoes falling, interior of the axon, like a line of dominoes falling, each one tripping the next ion channel changing each one tripping the next ion channel changing the polarity of the nerve cell (all the way down the polarity of the nerve cell (all the way down the axon and into the axon terminal). the axon and into the axon terminal).

A handful of neurons together produce enough A handful of neurons together produce enough power to light up a flashlight bulb.power to light up a flashlight bulb.

Neurons, like batteries, generate electricity from Neurons, like batteries, generate electricity from chemical events.chemical events.

This involves the exchange of This involves the exchange of electrically charged electrically charged atomsatoms, called , called ionsions..

Neural CommunicationNeural Communication

From hundreds, even thousands of other neurons, From hundreds, even thousands of other neurons, a single neuron receives signals on its dendrites a single neuron receives signals on its dendrites and cell body.and cell body. Some signals are Some signals are excitatoryexcitatory, somewhat like pushing , somewhat like pushing

a neurona neuron’’s accelerator.s accelerator. Some signals are Some signals are inhibitoryinhibitory, more like pushing the , more like pushing the

brakes, signaling the neuron to stop sending an brakes, signaling the neuron to stop sending an electrical impulse.electrical impulse.

The neuronThe neuron’’s threshold for firing an impulse is an s threshold for firing an impulse is an all-all-or-none responseor-none response, like a gun – it either fires or it , like a gun – it either fires or it doesndoesn’’t.t.

Neurons interweave so intricately that even with a Neurons interweave so intricately that even with a microscope it is hard to see where one neuron ends microscope it is hard to see where one neuron ends and another begins.and another begins.

The axon terminal of one neuron and the dendrite of The axon terminal of one neuron and the dendrite of another neuron are separated by a gap less than a another neuron are separated by a gap less than a millionth of an inch wide. This gap is called the millionth of an inch wide. This gap is called the SYNAPSESYNAPSE..

LetLet’’s Do the Neuron Dance!!!s Do the Neuron Dance!!!

NeurotransmittersNeurotransmitters

Chemical messengers released by Chemical messengers released by terminal buttons through the terminal buttons through the synapsesynapse

We should know at least 5 types and We should know at least 5 types and what they do.what they do.

NorepinephrineNorepinephrine

Circuits in the brain arise from a small Circuits in the brain arise from a small collection of neurons in the brain stem and collection of neurons in the brain stem and project to all forebrain structures. It is project to all forebrain structures. It is thought to moderate levels of arousal and thought to moderate levels of arousal and consolidate memory (interneuron).consolidate memory (interneuron).

AcetylcholineAcetylcholineIts function is motor movement Its function is motor movement

and maybe memory.and maybe memory.

To much and you will….

Not enough and you will….

Lack of ACH has been linked to Alzheimer’s disease.

DopamineDopamine Deals with motor Deals with motor movement and movement and alertness.alertness.

Lack of dopamine has Lack of dopamine has been linked to been linked to ParkinsonParkinson’’s disease.s disease.

Too much has been Too much has been linked to linked to schizophrenia.schizophrenia.

SerotoninSerotonin Function deals with mood Function deals with mood

controlcontrol

Lack of serotonin has been linked to depression

This is one mildly depressed sheep!!!  I guess we should try to shear her up (get it?) 

EndorphinsEndorphins Function deals with pain controlFunction deals with pain control Produces Produces ““runnerrunner’’s highs high”” We become addicted to We become addicted to

endorphin- causing feelings.endorphin- causing feelings.

Drugs can be…..Drugs can be…..

AgonistsAgonists- make neuron fire / - make neuron fire / produce temporary high by produce temporary high by amplifying sensations of arousal or amplifying sensations of arousal or pleasurepleasure

AntagonistsAntagonists- stop neural firing / - stop neural firing / inhibitinhibit

Reuptake InhibitorsReuptake Inhibitors- - block block reuptake; the sending neuron reuptake; the sending neuron normally reabsorbs excess normally reabsorbs excess neurotransmitter molecules neurotransmitter molecules