Welcome it is a great day to learn about the Brain
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What does the Brain do? Rally Robin with your shoulder partner
EVERYTHING your brain does
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We are going to start small and go big
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Neurons: The Building Blocks of the Nervous System
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Nervous System The electrochemical communication system of the
body Sends messages from the brain to the body for movement Brings
information to the brain from the senses
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Neuron The basic building block of the nervous system -- a
nerve cell Neurons perform three basic tasks Receive information
Carry the information Pass the information on to the next
neuron
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Types of Neurons SensoryMotor Interneuron's
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Spinal Cord Brain Sensory Neuron Sensory Neurons INPUT From
sensory organs to the brain and spinal cord Drawing shows a somatic
neuron
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Motor Neurons OUTPUT From the brain and spinal cord to the
muscles and glands Spinal Cord Brain Sensory Neuron Motor
Neuron
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Spinal Cord Brain Sensory Neuron Motor Neuron Interneuron's
Interneurons carry information between other neurons only found in
the brain and spinal cord
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The Basic Parts of a Neuron
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What are the primary parts of a typical neuron? Nervous system
Neurons Dendrites Soma Axon Terminal branches of Axon Myelin
Sheath
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The Basic Parts of a Neuron
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Parts of the Neuron
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A. Dendrites Thin, branching fibers lined with receptors at
which the dendrite receives information from other neurons.
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Parts of the Neuron - Dendrites
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B. Cell Body/Soma Contains the nucleus and other parts of the
cell needed to sustain life
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Parts of the Neuron - Soma
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C. Axon Carries the message across the neuron
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Parts of the Neuron - Axon
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D. Myelin Sheath An insulating, fatty covering around the axon
that speeds neural transmissions. Axons that are myelinated appear
white. Known as white matter.
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Parts of the Neuron Myelin Sheath
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E. Axon Terminal Buttons The branched end of the axon that
contains neurotransmitters
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Parts of the Neuron - Terminals
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Time to Move Locate the person furthest from you Go to that
person Introduce yourself
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Stand up, hand up, pair up wait
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Neuron
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Neuron
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Neural Transmission
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Neural Communication: The Neural Impulse
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Action Potential A brief electrical charge that travels down
the axon of the neuron. A neural impulse Considered an on condition
of the neuron
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Refractory Period The recharging phase when a neuron, after
firing, cannot generate another action potential Once the
refractory period is complete the neuron can fire again
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Resting Potential The state of a neuron when it is at rest and
capable of generating an action potential The neuron is set and
ready to fire
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Neuron firing like a Toilet 1. Like a Neuron, a toilet has an
action potential. When you flush, an impulse is sent down the sewer
pipe
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Neuron firing like a Toilet 2. Like a neuron, a toilet has a
refractory period. There is a short delay after flushing when the
toilet cannot be flushed again because the tank is being
refilled
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Neuron firing like a Toilet 3. Like a Neuron, a toilet has a
resting potential. The toilet is charged when there is water in the
tank and it is capable of being flushed again 4. Like a Neuron, a
toilet operates on the all-or-none principle it always flushes with
the same intensity, no matter how much force you apply to the
handle
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All-or-None Principle The principle that if a neuron fires it
will always fire at the same intensity All action potentials are of
the same strength. A neuron does NOT fire at 30%, 45% or 90% but at
100% each time it fires.
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Communication Between Neurons Module 7: Neural and Hormonal
Systems
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Synapse The space between the terminal buttons on one neuron
and dendrites of the next neuron
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Neurotransmitters Chemicals contained in the terminal buttons
that enable neurons to communicate. Neurotransmitters fit into
receptor sites on the dendrites of neurons like a key fits into a
lock.
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Neurotransmitters
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Neurotransmitters A chemical messenger that travels across the
synapse from one neuron to the next Can influence whether the
second neuron will generate an action potential or not
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Excitatory Effect A neurotransmitter effect that makes it more
likely that the receiving neuron will generate an action potential
(impulse) The second neuron is more likely to fire.
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Inhibitory Effect A neurotransmitter effect that makes it less
likely that the receiving neuron will generate an action potential
(impulse) The second neuron is less likely to fire.
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Neurotransmitters
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Acetylcholine (Ach) Found in neuromuscular junctions Involved
in muscle movements Involved in learning and memory Involved in REM
sleep
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Disruption of Acetylcholine Functioning Nerve gases and Black
Widow spider venom too much ACh leads to severe muscle spasms and
possible death Cigarettes nicotine works on ACh receptors can
artificially stimulate skeletal muscles, leading to slight
trembling movements
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Acetylcholine - Alzheimers Disease Deterioration of memory,
reasoning, and language skills Symptoms may be due to loss of ACh
neurons
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Dopamine Involved in movement, attention, and learning Reward
and motivation drugs can impair this greatly
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Dopamine - problems Dopamine imbalance also involved in
schizophrenia Loss of dopamine-producing neurons is cause of
Parkinsons disease
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Parkinsons Disease Results from loss of dopamine-producing
neurons in the substantia nigra Symptoms include difficulty
starting and stopping voluntary movements tremors at rest stooped
posture rigidity poor balance
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Serotonin Affects mood, hunger, sleep, and arousal Emotional
states
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Serotonin Problems Involved in depression Prozac works by
keeping serotonin in the synapse longer, giving it more time to
exert an effect
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Endorphins Natural opiates that are released in response to
pain and vigorous exercise Positive emotions
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Norepinephrine Physical Arousal Fight or flight response Works
with the sympathetic nervous system Learning memory
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Norepinephrine Problems: depression and stress
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GABA Muscular movement; inhibition of brain activity
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GABA PROBLEMS: Undersupply linked to seizures, tremors, and
insomnia Anxiety disorders
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GABA Huntingtons disease involves loss of neurons in striatum
that utilize GABA Symptoms: jerky involuntary movements mental
deterioration
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Epinephrine Adrenaline Burst of Energy (small amounts in brain)
Works with the endocrine system to ensure lasting energy from
threats
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Epinephrine problems Can lead to chronic stress syndrome
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Glutamate Involved in memory
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Glutamate Oversupply can over stimulate the brain, producing
migraines or seizures
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Drugs and Chemical Interactions with Neural Transmission
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Prozac blocking the re-uptake of Serotonin
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Neural Communication: The Neural Chain Module 7: Neural and
Hormonal Systems
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Receptor Cells Specialized cells in the sensory systems of the
body that can turn other kinds of energy into action potentials
that the nervous system can process Receptor cells in the eye turn
light into a neural impulse the brain understands.
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Sensory Nerves Nerves that carry information to the central
nervous system Connect the sense organs to the brain and spinal
cord
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Interneuron's Nerve cells in the brain and spinal cord
responsible for processing information related to sensory input and
motor output
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Motor Nerves Nerves that carry information from the central
nervous system Carries messages from the brain and spinal cord to
other parts of your body
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A Neural Chain
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Most information travels from the body, up the spinal cord, is
processed by the brain, sent back down the spinal cord, and then
back to the body with behavior instructions. The exception to this
general pathway is reflexes.
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Reflexes are controlled by the spinal cord without any
conscious effort on behalf of the brain. Reflexes serve as
primitive responses that protect our bodies from danger and help us
adjust to our surroundings.
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Reflex We cough, for example, when an irritant enters our
windpipe and we need to expel it through our mouth. We sneeze when
we need to clear our nasal air passages of irritants and allergens.
We blink when danger threatens the sensitive tissues of the eye and
when we need to moisten and clean the cornea. (This reflex occurs
900 times an hour!) We yawn when nerves in the brain stem find
there's too much carbon dioxide in the blood.