The Body and the The Body and the BrainBrain

The Nervous SystemThe Nervous System The nervous system regulates our internal functions.The nervous system regulates our internal functions. The The central nervous systemcentral nervous system consists of the brain and the consists of the brain and the

spinal cord.spinal cord. The The peripheral nervous systemperipheral nervous system is made up of nerve cells is made up of nerve cells

that send messages between the central nervous system and that send messages between the central nervous system and all the parts of the body.all the parts of the body.

Neurons Neurons - or nerve cells – run through our bodies and - or nerve cells – run through our bodies and communicate with each other.communicate with each other.

Neurons send and receive messages from other structures Neurons send and receive messages from other structures of the body, such as muscles and glands.of the body, such as muscles and glands.

Each of us has over 100 billion neurons – mostly found in Each of us has over 100 billion neurons – mostly found in our brains.our brains.

Neurons look like trees.Neurons look like trees. Each neuron is made up of a Each neuron is made up of a cell bodycell body, a , a dendritedendrite, and , and an an

axonaxon.. The The cell body cell body looks like the top of the trunk. looks like the top of the trunk. The cell The cell

body produces energy that fuels the activity of the cellbody produces energy that fuels the activity of the cell.. The axons look like the root of a tree. They carry The axons look like the root of a tree. They carry

messages away from the center cell body.messages away from the center cell body. The The dendrites dendrites look like the branches of the tree. look like the branches of the tree. They They

receive information from other neurons and pass the receive information from other neurons and pass the message through the cell bodymessage through the cell body..

Some neurons are as small as an inch in Some neurons are as small as an inch in length.length.

Others, like the neurons that run through Others, like the neurons that run through our legs, can be several feet long.our legs, can be several feet long.

Myelin is a white fatty substance that Myelin is a white fatty substance that insulates and protects the axon.insulates and protects the axon.

The myelin casing also helps to speed up The myelin casing also helps to speed up the transmission of the message.the transmission of the message.

The fibers at the end of the axon are The fibers at the end of the axon are called called axon terminalsaxon terminals..

Messages are sent from the Messages are sent from the axon terminalsaxon terminals of one neuron to the of one neuron to the dendritesdendrites of other of other neurons.neurons.

In order for the messages to be sent to In order for the messages to be sent to each other, they must travel across the each other, they must travel across the synapse – or the junction between thesynapse – or the junction between the axon axon terminalsterminals of one neuron and the dendrites of one neuron and the dendrites of another.of another.

The coolest part about the synapse is the The coolest part about the synapse is the fact that new ones develop between neurons fact that new ones develop between neurons when we learn something new.when we learn something new.

Neurons travel in varying directions Neurons travel in varying directions depending on the message.depending on the message.

For example, when you stub your toe, the For example, when you stub your toe, the sensory neurons sensory neurons carry information received carry information received by the senses to the central nervous system.by the senses to the central nervous system.

Motor neuronsMotor neurons are the nerve cells that carry are the nerve cells that carry information from the CNS to the muscles and information from the CNS to the muscles and glands and influence their functions.glands and influence their functions.

When you touch the hot stove, the When you touch the hot stove, the sensory sensory neuronsneurons tell the CNS that the stove is hot.tell the CNS that the stove is hot.

The The motor neurons motor neurons then travel from the CNS then travel from the CNS to tell the muscle to move the hand away to tell the muscle to move the hand away from the stove.from the stove.

Other Other motor neurons motor neurons may stimulate the heart may stimulate the heart and make it beat faster because of the and make it beat faster because of the situation.situation.

A A neurotransmitterneurotransmitter is a chemical that is a chemical that is stored in sacs in the axon is stored in sacs in the axon terminals.terminals.

There are several types of There are several types of neurotransmitters.neurotransmitters.

When a person thinks about a friend, When a person thinks about a friend, waves their hand, or yawn, waves their hand, or yawn, neurotransmitters are involved.neurotransmitters are involved.

Dopamine is a neurotransmitter that is Dopamine is a neurotransmitter that is involved primarily in motor behavior.involved primarily in motor behavior.

A deficiency in dopamine levels A deficiency in dopamine levels contributes to Parkinson’s Disease – contributes to Parkinson’s Disease – which involves a loss of muscle control which involves a loss of muscle control filled in with tremors and rigid filled in with tremors and rigid movement.movement.

An excess of dopamine contribute to An excess of dopamine contribute to schizophrenia. schizophrenia.

The Central Nervous SystemThe Central Nervous System The The spinal cord spinal cord extends from the brain extends from the brain down the back, ending below the hips. down the back, ending below the hips.

The spinal cord is a column of nerves The spinal cord is a column of nerves and it is protected by the bones of and it is protected by the bones of the spine.the spine.

The spinal cord is also responsible The spinal cord is also responsible for for spinal reflexes.spinal reflexes.

A A spinal reflexspinal reflex is an automatic is an automatic response to something – like the hot response to something – like the hot stove/pull away situation.stove/pull away situation.

Why do we blink when dust gets in our Why do we blink when dust gets in our eyes? Why do some of us sneeze when eyes? Why do some of us sneeze when we sniff pepper? we sniff pepper?

The The peripheral nervous system peripheral nervous system lies lies outside the central nervous system.outside the central nervous system.

The The somatic nervous systemsomatic nervous system transmits transmits sensory messages to the CNS. sensory messages to the CNS.

The SNS allows us to experience the The SNS allows us to experience the difference between hot and cold, difference between hot and cold, pain and pleasure.pain and pleasure.

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

The autonomic nervous system is The autonomic nervous system is interesting because is can be interesting because is can be effected by emotion.effected by emotion.

The The fight-or-flight fight-or-flight response occurs because the response occurs because the sympathetic system is activated when a person is sympathetic system is activated when a person is “going into action”.“going into action”.

This This sympathetic systemsympathetic system can disturb the ANS. can disturb the ANS. Stress can cause digestion to falter, can increase Stress can cause digestion to falter, can increase and decrease the heartbeat in specific situations, and decrease the heartbeat in specific situations, and can elevate the blood pressure.and can elevate the blood pressure.

The The parasympathetic system parasympathetic system restores peace in the restores peace in the body.body.

ANSANS

THE BRAINTHE BRAIN The brain is divided into three sections: The brain is divided into three sections: the the HindbrainHindbrain, the , the MidbrainMidbrain, and the , and the ForebrainForebrain..

THE HINDBRAIN:THE HINDBRAIN: The The medulla medulla is involved in vital functions is involved in vital functions such as heart rate, blood pressure, and such as heart rate, blood pressure, and breathing.breathing.

The The PPons ons is located in the front of the is located in the front of the medulla and is involved in regulating body medulla and is involved in regulating body movement, attention, sleep, and alertness.movement, attention, sleep, and alertness.

The The cerebellum cerebellum is responsible for balance is responsible for balance and coordination. A person with an injured and coordination. A person with an injured cerebellum might walk funny or fall over.cerebellum might walk funny or fall over.

THE MIDBRAIN:THE MIDBRAIN: The midbrain contains the parts of The midbrain contains the parts of the brain that are involved in the brain that are involved in vision and hearing.vision and hearing.

The The reticular activating systemreticular activating system is is important for attention, sleep, and important for attention, sleep, and arousal.arousal.

Stimulation of this portion of the Stimulation of this portion of the brai makes us alert and increases brai makes us alert and increases brain activity.brain activity.

Some drugs, such as alcohol, reduce Some drugs, such as alcohol, reduce the activity of the RAS, which mean the activity of the RAS, which mean the alertness and reaction time will the alertness and reaction time will decrease.decrease.

THE FOREBRAIN:THE FOREBRAIN: The forebrain contains four key areas.The forebrain contains four key areas. The The thalamus thalamus is a relay station for is a relay station for sensory stimulation.sensory stimulation.

The thalamus transmits sensory input The thalamus transmits sensory input such as pain or images captured by the such as pain or images captured by the eyes.eyes.

The The hypothalamus hypothalamus (hypo – Greek prefix (hypo – Greek prefix meaning “under”) is located under the meaning “under”) is located under the thalamus.thalamus.

The hypothalamus regulates body The hypothalamus regulates body temperature, hunger, thirst, sexual temperature, hunger, thirst, sexual behavior, caring for offspring, etc.behavior, caring for offspring, etc.

The hypothalamus is all about The hypothalamus is all about instinct, but humans, unlike animals, instinct, but humans, unlike animals, use cognitive thoughts – not just use cognitive thoughts – not just instinct.instinct.

The The limbic systemlimbic system is involved in learning is involved in learning and memory, emotion, hunger, sex, and and memory, emotion, hunger, sex, and aggression. aggression.

If a part of the limbic system is damaged, If a part of the limbic system is damaged, people can remember old memories, but cannot people can remember old memories, but cannot form new memories.form new memories.

Damage can also lead people to act passively Damage can also lead people to act passively or aggressively without cause.or aggressively without cause.

The The cerebrum cerebrum (Latin for brain) makes up 70% (Latin for brain) makes up 70% of the weight of the brain.of the weight of the brain.

The The cerebral cortex cerebral cortex is the outer layer of is the outer layer of the brain. the brain.

It is composed of two sides – the right and It is composed of two sides – the right and the left. Each side is called a hemisphere.the left. Each side is called a hemisphere.

The information transmitted from one side is The information transmitted from one side is transmitted to the transmitted to the otherother side of the body. side of the body.

The structure that connects the two The structure that connects the two hemispheres is the hemispheres is the corpus callosumcorpus callosum..

The Two SidesThe Two Sides The The cerebral cortex cerebral cortex is is

composed of two sides – or composed of two sides – or hemispheres.hemispheres.

HemiHemi – Greek for “half” – Greek for “half” The left hemisphere controls The left hemisphere controls

the the rightright side of your body. side of your body. The right hemisphere The right hemisphere

controls the controls the leftleft side of side of your body.your body.

The The corpus callosum corpus callosum aids in aids in getting info from one side getting info from one side to the other.to the other.

For right-handed people, For right-handed people, language originates on the language originates on the left.left.

The language functions are The language functions are usually associated with math usually associated with math and logic.and logic.

People who are supposedly People who are supposedly logical are logical are “left-brained”.“left-brained”.

The right brain (non-The right brain (non-language side) is more language side) is more emotional, creative.emotional, creative.

““Right-Brain”Right-Brain” types are types are artistic and imaginative. artistic and imaginative.

However, this “right/Left-However, this “right/Left-brain” is mostly invalid and brain” is mostly invalid and based on myth.based on myth.

The LobesThe Lobes Each hemisphere has four Each hemisphere has four

parts, or lobes.parts, or lobes. The The frontal lobefrontal lobe is is

sometimes called the sometimes called the “executive center” “executive center”

This is where we solve This is where we solve problems, make decisions, problems, make decisions, and store working memory.and store working memory.

Within the Within the frontal lobefrontal lobe, , Broca’s areaBroca’s area controls controls facial muscles – so when facial muscles – so when people injure this area, people injure this area, they may speak slowly and they may speak slowly and simply.simply.

The The occipital lobe occipital lobe contains the primary contains the primary visual area of the visual area of the cortex.cortex.

When light strikes the When light strikes the eye, neurons in the eye, neurons in the occipital lobe fire, occipital lobe fire, allowing us to see.allowing us to see.

Damage to this lobe can Damage to this lobe can cause people to recognize cause people to recognize an object, but they could an object, but they could be unable to be unable to differentiate that object differentiate that object from a similar object.from a similar object.

Skin sensations are Skin sensations are felt through the felt through the parietal lobeparietal lobe..

Different neurons Different neurons fire depending on fire depending on the sensation – the sensation – such as stubbing such as stubbing your toe, or your toe, or getting stung by a getting stung by a bee.bee.

The The temporal lobetemporal lobe collects sounds collects sounds picked up by the picked up by the thalamus – and we thalamus – and we hear sounds!hear sounds!

Association areas Association areas shape information shape information into something into something meaningful, and meaningful, and each lobe has its each lobe has its own association own association area.area.

Let’s ReviewLet’s Review 2 parts of the nervous system2 parts of the nervous system

– Central Nervous SystemCentral Nervous System– Peripheral Nervous SystemPeripheral Nervous System

3 sections of the brain3 sections of the brain– HindbrainHindbrain

Lower portion, vital functions, balance and Lower portion, vital functions, balance and coordinationcoordination

– MidbrainMidbrain Vision and hearingVision and hearing

– ForebrainForebrain Complex thought and emotionsComplex thought and emotions

4 association areas of the brain (make 4 association areas of the brain (make meaning of information, located in the meaning of information, located in the cebral cortex)cebral cortex)– Frontal, parietal, occipital, temporalFrontal, parietal, occipital, temporal

The Two SidesThe Two Sides The The cerebral cortex cerebral cortex is is

composed of two sides – or composed of two sides – or hemispheres.hemispheres.

HemiHemi – Greek for “half” – Greek for “half” The left hemisphere controls The left hemisphere controls

the the rightright side of your body. side of your body. The right hemisphere The right hemisphere

controls the controls the leftleft side of side of your body.your body.

The The corpus callosum corpus callosum aids in aids in getting info from one side getting info from one side to the other.to the other.

For right-handed people, For right-handed people, language originates on the language originates on the left.left.

The language functions are The language functions are usually associated with math usually associated with math and logic.and logic.

People who are supposedly People who are supposedly logical are logical are “left-brained”.“left-brained”.

The right brain (non-The right brain (non-language side) is more language side) is more emotional, creative.emotional, creative.

““Right-Brain”Right-Brain” types are types are artistic and imaginative. artistic and imaginative.

However, this “right/Left-However, this “right/Left-brain” is mostly invalid and brain” is mostly invalid and based on myth.based on myth.

Right brain v. left brainRight brain v. left brain Even though there are some characteristics Even though there are some characteristics that are associated with each hemisphere, the that are associated with each hemisphere, the corpus callosumcorpus callosum allows the hemispheres to allows the hemispheres to work together (rather than separately)work together (rather than separately)

When the corpus callosum is damaged (or cut When the corpus callosum is damaged (or cut in surgery), the communication between in surgery), the communication between hemispheres is altered, and that does effect hemispheres is altered, and that does effect some functionssome functions– If a patient holds an object in their left hand If a patient holds an object in their left hand (projected to the right hemisphere, the “non-(projected to the right hemisphere, the “non-language” side, then the left brain might not be language” side, then the left brain might not be able to communicate and say what the object isable to communicate and say what the object is

This situation demonstrates something called This situation demonstrates something called hemispheric specialization, which means hemispheric specialization, which means certain functions are controlled by a certain certain functions are controlled by a certain side of the brain (AKA brain lateralization)side of the brain (AKA brain lateralization)

Testing the BrainTesting the Brain Accidents give researchers a window into the brain.Accidents give researchers a window into the brain. Examples, such as Phineas Gage, show psychologists and scientists Examples, such as Phineas Gage, show psychologists and scientists

how different parts of the brain respond to damage.how different parts of the brain respond to damage. In 1969, In 1969, Jose DelgadoJose Delgado experimented with electrical stimulation on experimented with electrical stimulation on

the brain.the brain. He determined that when an implanted electrode in a bull’s brain, He determined that when an implanted electrode in a bull’s brain,

he could use electrical charges to stop a bull in the middle of a he could use electrical charges to stop a bull in the middle of a charge.charge.

Basically, his thesis stated that electrical stimulation to Basically, his thesis stated that electrical stimulation to various parts of the brain could change behaviorvarious parts of the brain could change behavior. .

An EEG – or An EEG – or electroencephalogramelectroencephalogram – is a device that records the – is a device that records the electrical activity of the brain.electrical activity of the brain.

Electrodes attached to the skull pick up on the electrical charges Electrodes attached to the skull pick up on the electrical charges – called brain waves – and patterns of these waves can be – called brain waves – and patterns of these waves can be associated with sleep, thought, and relaxation.associated with sleep, thought, and relaxation.

A CAT – or A CAT – or computerized axial tomographycomputerized axial tomography – scan determines how – scan determines how dense brain tissue is by recording how much radiation is absorbed dense brain tissue is by recording how much radiation is absorbed by an X-ray.by an X-ray.

A MRI- A MRI- magnetic resonance imaging-magnetic resonance imaging- a person lies in a powerful a person lies in a powerful magnetic field and radio wave cause the brain to give off energy- magnetic field and radio wave cause the brain to give off energy- more powerful than a CAT scanmore powerful than a CAT scan

A PET – orA PET – or Positron Emission TomographyPositron Emission Tomography – shows brain activity as – shows brain activity as it occurs so researchers can see which parts of the brain are it occurs so researchers can see which parts of the brain are stimulated when listening to music, performing math, or having a stimulated when listening to music, performing math, or having a discussion with friends.discussion with friends.

PET scanPET scan

CAT scanCAT scan

MRI of brain on MethMRI of brain on Meth

GLANDSGLANDS The The endocrine system endocrine system consists of glands that consists of glands that

secrete substances called secrete substances called hormoneshormones into the into the bloodstream.bloodstream.

Hormones Hormones stimulate growth and reactions, such as stimulate growth and reactions, such as changes in mood and activity levels.changes in mood and activity levels.

Hormones are produced by several different Hormones are produced by several different glands.glands.

The The pituitary glandpituitary gland (just the size of a pea and (just the size of a pea and situated under the hypothalamus), controls growth situated under the hypothalamus), controls growth hormones, hormones (hormones, hormones (OxytocinOxytocin) that stimulate ) that stimulate labor for pregnant women, and “mothering labor for pregnant women, and “mothering instincts”.instincts”.

The The thyroid glandthyroid gland produces thyroxin which affects produces thyroxin which affects the body’s metabolism.the body’s metabolism.

Too little thyroxin leads to hypothyroid disorder Too little thyroxin leads to hypothyroid disorder – and these people can be overweight.– and these people can be overweight.

Too much thyroxin leads to hyperthyroid disorder, Too much thyroxin leads to hyperthyroid disorder, which can make people lose weight, become which can make people lose weight, become hyperactive, or sleepless.hyperactive, or sleepless.

The The adrenal glands adrenal glands are located above the kidneys are located above the kidneys and secrete cortical steroids.and secrete cortical steroids.

Cortical steroids increase resistance to stress Cortical steroids increase resistance to stress and promote muscle development.and promote muscle development.

The The adrenaladrenal glands also release glands also release adrenalineadrenaline… meant … meant to help people in a stressful situation.to help people in a stressful situation.

Nonadrenaline also steps in to help calm people Nonadrenaline also steps in to help calm people during the stressful situation, whereas adrenaline during the stressful situation, whereas adrenaline prepares people for a fight. (Fight-or-Flight prepares people for a fight. (Fight-or-Flight response)response)

The The Testes Testes produce testosterone and small amounts produce testosterone and small amounts or estrogen and progesterone in males.or estrogen and progesterone in males.

It is responsible for pushing boys through puberty It is responsible for pushing boys through puberty so that they are ready to reproduce.so that they are ready to reproduce.

The The ovaries ovaries produce estrogen and progesterone and produce estrogen and progesterone and small amounts of testosterone in women.small amounts of testosterone in women.

Again, the ovaries prepare women for puberty – Again, the ovaries prepare women for puberty – which lead to reproduction and childbirth.which lead to reproduction and childbirth.

Really, sexual attraction is very chemical (or Really, sexual attraction is very chemical (or hormonal) because women have higher libido’s when hormonal) because women have higher libido’s when they are ovulating because there is more estrogen they are ovulating because there is more estrogen in their body.in their body.

HeredityHeredity Heredity Heredity is the transmission of characteristics is the transmission of characteristics

from parents to offspring.from parents to offspring. Heredity – while determining hair color, eye color Heredity – while determining hair color, eye color

and height – can also determine some psychological and height – can also determine some psychological traits.traits.

Shyness, leadership, aggressiveness, etc., can be Shyness, leadership, aggressiveness, etc., can be linked to heredity.linked to heredity.

However, for years, the debate has raged on about However, for years, the debate has raged on about Nature vs. NurtureNature vs. Nurture..

Does heredity really determine behavior?Does heredity really determine behavior? Or is it purely based on upbringing?Or is it purely based on upbringing? As humans, we loath the nature idea because it As humans, we loath the nature idea because it

states that everything is predetermined – meaning states that everything is predetermined – meaning that we cannot become smarter or more athletic that we cannot become smarter or more athletic than our biology allows.than our biology allows.

Psychologists argue that heredity cannot determine Psychologists argue that heredity cannot determine destiny because the environment DOES determine how destiny because the environment DOES determine how a person develops.a person develops.

The best way to test this debate is by studying….?The best way to test this debate is by studying….? Twins.Twins. Identical twins share 100% of their genes. Identical twins share 100% of their genes. Their DNA is identical, yet their fingerprints are Their DNA is identical, yet their fingerprints are

different…different… Fraternal twins, however, only share about 50% of Fraternal twins, however, only share about 50% of

their genes.their genes. Therefore, identical twins are more likely to Therefore, identical twins are more likely to

share traits – both positive and negative.share traits – both positive and negative. Identical twins, for example, are more likely to Identical twins, for example, are more likely to

both develop autism than fraternal twins.both develop autism than fraternal twins. Beginning in 1979, Thomas Bouchard began studying Beginning in 1979, Thomas Bouchard began studying

twins that were being reared aparttwins that were being reared apart.. He found that twins who had never met one another He found that twins who had never met one another

– and had been “nurtured” differently – still – and had been “nurtured” differently – still shared unique mannerismsshared unique mannerisms..

Researchers also study adopted children because Researchers also study adopted children because they are removed from their biological families they are removed from their biological families and can still share commonalities with their and can still share commonalities with their actual parentsactual parents..

These studies can be controversial because it These studies can be controversial because it relies on twins, siblings, or children to remain relies on twins, siblings, or children to remain apart – which is difficult to maintain ethically apart – which is difficult to maintain ethically at times.at times.