Transcript Project Self-Discovery

Project Self-Discovery
A step-by-step journey through the
parts of our bodies that govern our
actions, pain, pleasures, thoughts, and
emotions
You will learn what makes you tick at the following levels within your human body:
Cellular
Systems
Brain
Central Nervous and Peripheral Nervous Systems
exterior view of right hemisphere
A neuron
neural network
Interior view of right hemisphere
Endocrine system
Neurons (AKA nerve cells)
The cells that make you what and who you are!
– Function:
• to send and receive electrical pulses between skin, muscles, organs, glands, spine
& brain
• these pulses govern our every thought, emotion, and movement!!
– Facts:
• Human body has 100s of billions; most are in the brain and spine
• Second most neuron rich place is your gut (which is called the second brain by
some!)
• 1 sand grain-sized piece of brain can have 100,000 neurons and 1 MILLION
synapses (small space between neurons across which messages are sent)
• Types Different kinds for different messages and functions
• motor (efferent)—send outgoing messages from brain to move muscles
• sensory (afferent)—receive incoming messages and send to brain
• inter—neurons of brain and spine that receive messages from sensory neurons
and send messages to motor neurons
• mirror--only in frontal lobe of brain, these neurons in the brain that “act out” and
help us imitate the actions of others without conscious thought on our parts!
Anatomy of a neuron
Draw and label a neuron on your notes including
cell body (soma)
axon
dendrites
axon terminals
Schwann’s cells
myelin sheath
Node of Ranvier
Label the functions of the parts
Axon:
sends
messages
Dendrites:
receive
messages
Neural network:
cluster of neurons in brain
1. Networks grow more and
stronger synaptic
connections as we learn,
think, do because of LTP!
Neurons generate more
dendrites to “speak” with
axons of neighboring
neurons
Neural pruning: The brain destroys connections that aren’t
being used because they are wasting valuable resources!!
2. Connections weaken
when not used because of
neural pruning
They can also be damaged
by drugs, alcohol, disease,
surgery, TBI (traumatic
brain injury)
Neural impulse
• Energy that travels up to 200 mph through your body from
one neuron to the next (in contrast, electricity travels 3
million times faster in a wire!)
• The energy carries a message to the brain and other cells in
body from external stimuli (heat, pressure, light, sound) OR a
message generated within the body
• Impulse is processed and “translated” into image, sound,
emotion, pain, etc. in brain
• Brain can send out response impulses to muscles and skin
Synaptic communication
Neurons “fire” when they
are stimulated to the point
of having an action
potential
Neurons exist at resting
potential and when
stimulated have an action
potential
Video of neural communication NO narration
Neurotransmitters: The chemical language of the body
• Neural impulse (energy messages) are transmitted between neurons
across synaptic gap (small space between neurons) by
neurotransmitters
• Neurons are specialized to send and receive specific neurotransmitters
like keys to a door
Excitatory vs. inhibitory neurotransmitters
Inhibitory slow down neural
1. Read and highlight the handout according to the
impulses, calm the brain,
following color codes:
bring mood back to
homeostasis after highly
a) one color for function(s) of the neurotransmitter
stimulating event by opening
b) another color for effects of too much
up K+ gates and
c) another color for effects of a deficit of this
hyperpolarizing neuron so
neurotransmitter
that it can’t have an action
2. Make a tree map that states the definition of excitatory potential
and inhibitory neurotransmitters and lists the 6 that
are described in the reading in the right category.
3. On your map, identify the functions of each
Excitatory speed up
neurotransmitter AND what happens as levels
neural impulses,
fluctuate.
stimulate the brain by
allowing Na+ gates to
open and begin an
action potential
Neurotransmitters released by axon across synaptic gap (cleft) to
neighboring neuron’s dendrite
Video snippet: Neural communication
Time for a field trip & to act it out!!
1. To the men’s urinal we go!
Quick write: How is a men’s urinal a metaphor for action potential? Be sure to include
the following terms in your description:
•
•
•
•
•
•
•
•
•
•
resting potential
• flush “detector” (or handle)
threshold
• water flowing from top to basin
neural impulse
• urinal body
all-or-nothing principle
• urinal basin
direction of flow of impulse
• soap thing at bottom of basin
dendrites
• drain
synaptic vesicles
2. Act it out!
neurotransmitters
Stand up
axon terminals
You are now a neuron—Let’s do the neuron dance!!
refractory period
Go find another neuron to send an impulse to
Reuptake & reuptake inhibitors
Things that can make our neural communication dysfunctional
A. Reuptake: Natural neural process—
a) Sending neuron has reuptake sites that “suck” up the neurotransmitter from the
synapse after an action potential has occurred.
b) Neuron repackages the neurotransmitter into new synaptic vesicles to use again
B. Reuptake inhibitors: Molecules that bind to the reuptake sites on the axons preventing
reuptake of neurotransmitters
So what? If sending neuron can’t “mop up” the neurotransmitters from the synapse, they
will continue to link to receptor sites on other neuron’s dendrites causing continuous
action potentials!!
This can be a good thing or a bad thing!
a) Reuptake inhibitors are good if we are treating someone who has a deficit of a
particular neurotransmitter (see using SSRIs to treat depression)
b) Reuptake inhibitors are bad if they cause someone to get used to the high levels of
a particular neurotransmitter (see cocaine)
Reuptake inhibitor up close: Cocaine!
Why does cocaine make us feel so good and keep us wanting more??
Video snippet
a) They don’t call it “dope” for nothin’!
b) Cocaine is a reuptake inhibitor for dopamine
c) What does that mean? Quick write what the video taught you
about how cocaine interacts with our brains at the neural level
Serotonin and depression:
Selective serotonin reuptake inhibitors (SSRIs)
are main pharmaceutical treatment for depression
Video animation of SSRI
After video quick write: How do SSRIs work to
treat depression?
Agonists and antagonists
Things that can make our neural communication dysfunctional
A.
Agonists: Molecules that are similar enough to a
neurotransmitter to allow an action potential OR block
reuptake
– Opiates: drug that cause euphoria (extreme happiness) in
order to minimize pain (or get high!)
• heroine, codeine, morphine, opium
• agonists for endorphins
– Barbiturates: drugs that cause sedation (extreme
relaxation) in order to minimize pain and anxiety
• Barbiturates are agonists for GABA (Video snippet)
– Black widow spider venom is agonist for ACh leads to
violent muscle contractions, PAIN!
B. Antagonists: Molecules that are similar enough to a
neurotransmitter to lock into receptor sites on dendrites or
blocking the terminal buttons on axons thereby
STOPPING/PREVENTING action potentials
Botox, botulin: Block ACh release causing paralysis
Curare poison blocks ACh receptor sites causing paralysis
Quick look at Alzheimer’s disease
Alzheimer’s disease: a degenerative disease that causes person to lose
ability to transfer short-term to long-term memory and eventually disrupts
ability to retrieve long-term memory as well as lose functions of speech,
comprehension, and movement
How does it work?
Alzheimer’s disease attacks the brain’s neurons by disrupting the normal
work of proteins at the neural level
Alzheimer’s seems to attack neurons that produce the neurotransmitter
acetylcholine (ACh)
•ACh is linked with memory recall AND speed of processing information
Neural death due to plaques and tangles and shrinking brain cause the
symptoms of the disease
Practical Applications?
• If we know thoughts are energy (neural impulses), how can
we use this knowledge?
– Electrodes can deliver energy pulse to areas of the brain to find out
what that part does
– People who are paralyzed can have tiny transmitters implanted in their
brains that communicate their thoughts with computers
– Use electroconvulsive therapy to over-stimulate areas of brain
– Cut or create lesions on parts of brain to stop energy transmission
when there is too much (e.g. epileptic seizures)
Practical Applications?
• If we know how to replicate neurotransmitters in the
chemistry lab, how can that help people who don’t have
enough of one?
– Make drugs to replace/mimic the missing neurotransmitter!!
– Make drugs that increase or decrease flow of neurotransmitters (e.g.
Serotonin Reuptake Inhibitors)
• Why isn’t injecting someone with a missing neurotransmitter
always the answer?
– Blood-brain barrier (special blood vessels in brain that are
impermeable to most molecules) prevents many injected chemicals
from entering brain