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The Body and the Brain neurons first.ppt

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The Body and the Brain neurons first.ppt Powered By Docstoc
					The Body and the
     Brain
             The Nervous System
   The nervous system regulates our internal functions.
   The central nervous system consists of the brain and the spinal
    cord.
   The peripheral nervous system is made up of nerve cells that send
    messages between the central nervous system and all the parts of
    the body.
   Neurons - or nerve cells – run through our bodies and
    communicate with each other.
   Neurons send and receive messages from other structures of the
    body, such as muscles and glands.
   Each of us has over 100 billion neurons – mostly found in our
    brains.
   Neurons look like trees.
   Each neuron is made up of a cell body, a dendrite, and an axon.
   The cell body looks like the top of the trunk. The cell body
    produces energy that fuels the activity of the cell.
   The axons look like the root of a tree. They carry messages away
    from the center cell body.
   The dendrites look like the branches of the tree. They receive
    information from other neurons and pass the message through
    the cell body.
   Some neurons are as small as an inch in length.
   Others, like the neurons that run through our
    legs, can be several feet long.
   Myelin is a white fatty substance that insulates
    and protects the axon.
   The myelin casing also helps to speed up the
    transmission of the message.
   The fibers at the end of the axon are called axon
    terminals.
   Messages are sent from the axon terminals of
    one neuron to the dendrites of other neurons.
   In order for the messages to be sent to each
    other, they must travel across the synapse – or
    the junction between the axon terminals of one
    neuron and the dendrites of another.
   The coolest part about the synapse is the fact
    that new ones develop between neurons when we
    learn something new.
   Neurons travel in varying directions depending on
    the message.
   For example, when you stub your toe, the
    sensory neurons carry information received by
    the senses to the central nervous system.
   Motor neurons are the nerve cells that carry
    information from the CNS to the muscles and
    glands and influence their functions.
   When you touch the hot stove, the sensory
    neurons tell the CNS that the stove is hot.
   The motor neurons then travel from the CNS to
    tell the muscle to move the hand away from the
    stove.
   Other motor neurons may stimulate the heart
    and make it beat faster because of the situation.
 A neurotransmitter is a chemical that is
  stored in sacs in the axon terminals.
 There are several types of
  neurotransmitters.
 When a person thinks about a friend,
  waves their hand, or yawn,
  neurotransmitters are involved.
 Dopamine is a neurotransmitter that is
  involved primarily in motor behavior.
 A deficiency in dopamine levels
  contributes to Parkinson’s Disease – which
  involves a loss of muscle control filled in
  with tremors and rigid movement.
 An excess of dopamine contribute to
  schizophrenia.
    The Central Nervous System
 The spinal cord extends from the brain
  down the back, ending below the hips.
 The spinal cord is a column of nerves and
  it is protected by the bones of the spine.
 The spinal cord is also responsible for
  spinal reflexes.
 A spinal reflex is an automatic response to
  something – like the hot stove/pull away
  situation.
 Why do we blink when dust gets in our
  eyes? Why do some of us sneeze when
  we sniff pepper?
 The peripheral nervous system lies
  outside the central nervous system.
 The somatic nervous system
  transmits sensory messages to the
  CNS.
 The SNS allows us to experience the
  difference between hot and cold, pain
  and pleasure.
 The autonomic nervous system
  regulates the body’s vital functions,
  such as heartbeat, breathing,
  digestion, and blood pressure.
 The autonomic nervous system is
  interesting because is can be effected
  by emotion.
   The fight-or-flight response occurs because the
    sympathetic system is activated when a person is
    “going into action”.
   This sympathetic system can disturb the ANS. Stress
    can cause digestion to falter, can increase and
    decrease the heartbeat in specific situations, and can
    elevate the blood pressure.
   The parasympathetic system restores peace in the
    body.
ANS
                 THE BRAIN
   The brain is divided into three sections: the
    Hindbrain, the Midbrain, and the Forebrain.
   THE HINDBRAIN:
   The medulla is involved in vital functions
    such as heart rate, blood pressure, and
    breathing.
   The Pons is located in the front of the
    medulla and is involved in regulating body
    movement, attention, sleep, and alertness.
   The cerebellum is responsible for balance
    and coordination. A person with an injured
    cerebellum might walk funny or fall over.
 THE MIDBRAIN:
 The midbrain contains the parts of the
  brain that are involved in vision and
  hearing.
 The reticular activating system is
  important for attention, sleep, and
  arousal.
 Stimulation of this portion of the brai
  makes us alert and increases brain
  activity.
 Some drugs, such as alcohol, reduce the
  activity of the RAS, which mean the
  alertness and reaction time will decrease.
 THE FOREBRAIN:
 The forebrain contains four key areas.
 The thalamus is a relay station for sensory
  stimulation.
 The thalamus transmits sensory input
  such as pain or images captured by the
  eyes.
 The hypothalamus (hypo – Greek prefix
  meaning “under”) is located under the
  thalamus.
 The hypothalamus regulates body
  temperature, hunger, thirst, sexual
  behavior, caring for offspring, etc.
 The hypothalamus is all about instinct, but
  humans, unlike animals, use cognitive
  thoughts – not just instinct.
   The limbic system is involved in learning
    and memory, emotion, hunger, sex, and
    aggression.
   If a part of the limbic system is damaged,
    people can remember old memories, but
    cannot form new memories.
   Damage can also lead people to act
    passively or aggressively without cause.
   The cerebrum (Latin for brain) makes up
    70% of the weight of the brain.
   The cerebral cortex is the outer layer of the
    brain.
   It is composed of two sides – the right and
    the left. Each side is called a hemisphere.
   The information transmitted from one side is
    transmitted to the other side of the body.
   The structure that connects the two
    hemispheres is the corpus callosum.
                   The Two Sides
   The cerebral cortex is
    composed of two sides – or
    hemispheres.
   Hemi – Greek for “half”
   The left hemisphere controls
    the right side of your body.
   The right hemisphere controls
    the left side of your body.
   The corpus callosum aids in
    getting info from one side to
    the other.
   For right-handed people,
    language originates on the
    left.
   The language functions are
    usually associated with math
    and logic.
   People who are supposedly
    logical are “left-brained”.
   The right brain (non-language
    side) is more emotional,
    creative.
   “Right-Brain” types are
    artistic and imaginative.
   However, this “right/Left-
    brain” is mostly invalid and
    based on myth.
               Each hemisphere has four
                parts, or lobes.
The Lobes      The frontal lobe is
                sometimes called the
                “executive center”
               This is where we solve
                problems, make decisions,
                and store working
                memory.
               Within the frontal lobe,
                Broca’s area controls facial
                muscles – so when people
                injure this area, they may
                speak slowly and simply.
               The occipital lobe contains
                the primary visual area of
                the cortex.
               When light strikes the eye,
                neurons in the occipital
                lobe fire, allowing us to
                see.
               Damage to this lobe can
                cause people to recognize
                an object, but they could
                be unable to differentiate
                that object from a similar
                object.
   Skin sensations are
    felt through the
    parietal lobe.
   Different neurons
    fire depending on
    the sensation –
    such as stubbing
    your toe, or getting
    stung by a bee.
   The temporal lobe
    collects sounds
    picked up by the
    thalamus – and we
    hear sounds!
   Association areas
    shape information
    into something
    meaningful, and
    each lobe has its
    own association
    area.
                       Let’s Review
   2 parts of the nervous system
    – Central Nervous System
    – Peripheral Nervous System
   3 sections of the brain
    – Hindbrain
        Lower    portion, vital functions, balance and coordination
    – Midbrain
        Vision   and hearing
    – Forebrain
        Complex    thought and emotions
   4 association areas of the brain (make
    meaning of information, located in the cebral
    cortex)
    – Frontal, parietal, occipital, temporal
                   The Two Sides
   The cerebral cortex is
    composed of two sides – or
    hemispheres.
   Hemi – Greek for “half”
   The left hemisphere controls
    the right side of your body.
   The right hemisphere controls
    the left side of your body.
   The corpus callosum aids in
    getting info from one side to
    the other.
   For right-handed people,
    language originates on the
    left.
   The language functions are
    usually associated with math
    and logic.
   People who are supposedly
    logical are “left-brained”.
   The right brain (non-language
    side) is more emotional,
    creative.
   “Right-Brain” types are
    artistic and imaginative.
   However, this “right/Left-
    brain” is mostly invalid and
    based on myth.
           Right brain v. left brain
   Even though there are some characteristics that
    are associated with each hemisphere, the
    corpus callosum allows the hemispheres to work
    together (rather than separately)
   When the corpus callosum is damaged (or cut in
    surgery), the communication between
    hemispheres is altered, and that does effect
    some functions
    – If a patient holds an object in their left hand
      (projected to the right hemisphere, the “non-
      language” side, then the left brain might not be
      able to communicate and say what the object is
   This situation demonstrates something called
    hemispheric specialization, which means certain
    functions are controlled by a certain side of the
    brain (AKA brain lateralization)
                   Testing the Brain
   Accidents give researchers a window into the brain.
   Examples, such as Phineas Gage, show psychologists and scientists
    how different parts of the brain respond to damage.
   In 1969, Jose Delgado experimented with electrical stimulation on the
    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 charge.
   Basically, his thesis stated that electrical stimulation to various parts
    of the brain could change behavior.
   An EEG – or electroencephalogram – is a device that records the
    electrical activity of the brain.
   Electrodes attached to the skull pick up on the electrical charges –
    called brain waves – and patterns of these waves can be associated
    with sleep, thought, and relaxation.
   A CAT – or computerized axial tomography – scan determines how
    dense brain tissue is by recording how much radiation is absorbed by
    an X-ray.
   A MRI- magnetic resonance imaging- a person lies in a powerful
    magnetic field and radio wave cause the brain to give off energy- more
    powerful than a CAT scan
   A PET – or Positron Emission Tomography – shows brain activity as it
    occurs so researchers can see which parts of the brain are stimulated
    when listening to music, performing math, or having a discussion with
    friends.
PET scan
CAT scan
MRI of brain on Meth
                     GLANDS
   The endocrine system consists of glands that
    secrete substances called hormones into the
    bloodstream.
   Hormones stimulate growth and reactions, such as
    changes in mood and activity levels.
   Hormones are produced by several different glands.
   The pituitary gland (just the size of a pea and
    situated under the hypothalamus), controls growth
    hormones, hormones (Oxytocin) that stimulate
    labor for pregnant women, and “mothering
    instincts”.
   The thyroid gland produces thyroxin which affects
    the body’s metabolism.
   Too little thyroxin leads to hypothyroid disorder –
    and these people can be overweight.
   Too much thyroxin leads to hyperthyroid disorder,
    which can make people lose weight, become
    hyperactive, or sleepless.
   The adrenal glands are located above the kidneys
    and secrete cortical steroids.
   Cortical steroids increase resistance to stress and
    promote muscle development.
   The adrenal glands also release adrenaline… meant
    to help people in a stressful situation.
   Nonadrenaline also steps in to help calm people
    during the stressful situation, whereas adrenaline
    prepares people for a fight. (Fight-or-Flight
    response)
   The Testes produce testosterone and small amounts
    or estrogen and progesterone in males.
   It is responsible for pushing boys through puberty so
    that they are ready to reproduce.
   The ovaries produce estrogen and progesterone and
    small amounts of testosterone in women.
   Again, the ovaries prepare women for puberty –
    which lead to reproduction and childbirth.
   Really, sexual attraction is very chemical (or
    hormonal) because women have higher libido’s when
    they are ovulating because there is more estrogen in
    their body.
                     Heredity
   Heredity is the transmission of characteristics from
    parents to offspring.
   Heredity – while determining hair color, eye color
    and height – can also determine some psychological
    traits.
   Shyness, leadership, aggressiveness, etc., can be
    linked to heredity.
   However, for years, the debate has raged on about
    Nature vs. Nurture.
   Does heredity really determine behavior?
   Or is it purely based on upbringing?
   As humans, we loath the nature idea because it
    states that everything is predetermined – meaning
    that we cannot become smarter or more athletic than
    our biology allows.
   Psychologists argue that heredity cannot determine
    destiny because the environment DOES determine
    how a person develops.
   The best way to test this debate is by studying….?
   Twins.
   Identical twins share 100% of their genes.
   Their DNA is identical, yet their fingerprints are
    different…
   Fraternal twins, however, only share about 50% of
    their genes.
   Therefore, identical twins are more likely to share
    traits – both positive and negative.
   Identical twins, for example, are more likely to both
    develop autism than fraternal twins.
   Beginning in 1979, Thomas Bouchard began studying
    twins that were being reared apart.
   He found that twins who had never met one another
    – and had been “nurtured” differently – still shared
    unique mannerisms.
   Researchers also study adopted children because
    they are removed from their biological families and
    can still share commonalities with their actual
    parents.
   These studies can be controversial because it relies
    on twins, siblings, or children to remain apart –
    which is difficult to maintain ethically at times.

				
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