Neurotransmitter Criteria

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Neurotransmitter Criteria
What five criteria must a chemical meet if it is
to be considered a neurotransmitter?
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ProcessHow Neurotransmitters WorkStep 1
Release of Neurotransmitterfrom Pre-Synaptic
Neuron
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• synaptic terminal of pre-synaptic cell receives
  an action potential from axon
• this triggers neurotransmitter-containing
  vesicles at end of terminal to move
• vesicles merge with plasma membrane of terminal,
  releasing neurotransmitter into synaptic cleft

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ProcessHow Neurotransmitters WorkStep 2
Binding of Neurotransmitter with Receptor
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• neurotransmitter passes through synaptic cleft
• it then binds to a compatible receptor on the
  post-synaptic cell
• this binding triggers a change of some sort in
  the post-synaptic cell (either excitatory or
  inhibitory)

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ProcessHow Neurotransmitters WorkStep 3
Release and Deactivation of Neurotransmitter
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• once neurotransmitter has performed its function,
  it is released from the receptor
• it is then either taken back into the
  pre-synaptic cell (via reuptake channels) or is
  broken down in the synaptic cleft

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Important Neurotransmitters Acetylcholine (Ach)
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• main transmitter used in muscle contraction (this
  occurs at neuro-muscular junctions)
• formed when two precursors, Acetyl Co-A and
  choline, come together (with the help of enzyme
  choline acetyltransferase)
• released by cholinergic neurons
• received by nicotinic (fast-acting) and
  muscarinic (slow-acting) receptors
• when Ach binds with a receptor of a post-synaptic
  neuron, it triggers an influx of sodium (Na)
  ions and an efflux of potassium (K) ions,
  resulting in depolarization of that neuron
• broken down by the enzyme Acetylcholinesterase
  (AchE)

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Excitatory Neurotransmitters
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• Acetylcholine (Ach)
• Catecholamines
• Glutamate
• Histamine
• Serotonin
• Some neuropeptides

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Inhibitory Neurotransmitters
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• GABA
• Glycine
• Some peptides

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Agonist
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Mimics or increases the effect of a
neurotransmitter.
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Antagonist
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Reduces or blocks the effect of the
neurotransmitter.
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Thalamus
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-receives sensory signals except smell.
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Somatic Nervous System
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Skeletal muscle movement

• Voluntary

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BBB
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Blood-Brain Barrierblocks poisons and NTs from
entering the brain
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Binding Site
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(In the synaptic gap) the proteins/receptors in
the space are waiting to receive the
neurotransmitters
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SYNAPTIC CLEFT
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• A small gap between neurons where
  neurotransmitters are released. A neuron has many
  (thousands) synapses.

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VESICLES
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Small membrane enclosed packets located in
the axon terminal of the presynaptic neuron that
store neurotransmitters.
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GRADED POTENTIAL
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Opening ion channels produces a graded potential
causing either hyperpolarization or
depolarization.
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EPSP
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Excitatory postsynaptic potential caused by
depolarization of the dendrites and cell body
when receptors open Na channels theresult is
depolarization.EPSP increase the rate of neuron
firing.
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IPSP
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Inhibitory postsynaptic potential caused by
hyperpolarization of the dendrites and cell body.
If receptors open the K channels, Cl channels, or
both then as K moves out and Cl moves in the
result will be depolarization.IPSPdecreases
neuron firing rate.
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REUPTAKE
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• The neurotransmitter is taken back into the
  presynaptic terminals, repackaged in the
  vesicles, and used again.
• Sometimes, as is the case with Ach, the
  neurotransmitter is deactivated by an enzyme.
• Some drugs influence behavior by controlling
  amount of NT in the synapse.

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RECEPTOR TYPES
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• Ionotropic Receptors fast channels open Na
  channels bind directly to receptor site
  receptor is the channel
• Metabotropic Receptors slower channels NT does
  not bind directly to receptor but binds to a
  protein uses a protein to open the ion channel.

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Structure of the Synapse
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• Structure of the Synapse
• Presynaptic sending cell Releases
  neurotransmitter
• Postsynaptic receiving cell Contains receptors
  for neurotransmitter
• Synaptic cleft space in between pre- and
  postsynaptic cells
• Synaptic vesicle storage for neurotransmitter
  

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Axodendritic Synapse
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Axodendritic Synapse

• Axon to dendrite
• Excitatory

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Axosomatic Synapse
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• Axosomatic Synapse
• Axon to cell body
• Inhibitory

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Axoaxonic Synapse
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• Axoaxonic Synapse
• Axon to terminal endings
• Presynaptic inhibition
• Reduced polarity

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Opiates(Narcotics)
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• Include Heroin, Morphine, Opium, etc.
• they produce feelings of euphoria
• they are pain-relieving
• they are called hypnotic because they help you
  sleep
• they are direct agonists by affecting the release
  of dopamine
• they also stimulate endorphin receptors

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• Depressants
• (Sedative/Hypnotic, Anxiolytics)

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• includes Alcohol, Barbituates, Benzodiazepines
• Indirect GABA agonistsfacilitates the
  bonding.reduces CNS activityslows you
  down.reduces anxiety
• excessive use of alcohol can lead to reduced
  brain size and bigger ventricles

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• CNS Stimulants

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• activates the central nervous systemincreased
  alertness and mood
• Nicotine-stimulates ACh (acetlcholine)
  receptors.direct agonist
• Cocaine- agonist that stimulates massive release
  of dopamine and slows down the re-uptake of the
  neurotransmitter
• Amphetamines- stimulates release of
  dopamine..agonist
• Caffeine- blocks receptors for adenosine.and
  increases release of Ach and dopamine.agonist

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• Antipsychotics

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• for schizophrenia and bi-polar disorders
• direct antagonists
• Reserpine- make leaky vesicles in axon
  terminal..so little/no dopamine released
• Phenothiazines/Thorazine(chlorpromazine)- blocks
  dopamine receptors..which prevents dopamine from
  binding
• also includes Butyrophenones and Haldol

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Brocas area
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The part of the brain responsible for speech.
Founded by French physician Paul Broca
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What is the connection between two neurons called?
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A synapse
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What are the branches at the end of axons that
culminate in swellings called?
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Terminals
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What do all of these terms have in common?

• Dendrite, Soma, Nucleus, Axon hillock, Myelin
  sheath,

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They are all components of a neuron
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• The four lobes of the brain

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• 2 Frontal
• 2 Pariental
• 2 Occipital
• 2 Temporal

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• Function of pariental lobes

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• Processes the skin senses and the senses that
  inform us about body position and movement

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• Function of the frontal lobes

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• The frontal lobes is involved with the control of
  movement

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VENTRAL

• The ventral part of the brain is the part that is
  the most inferior when compared with another part.

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POSTERIOR

• Posterior means towards the rear

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ANTERIOR

• Anterior means towards the front

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DORSAL

• Dorsal means towards the back but when we are
  talking about the brain it is the upper most
  region

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Receptors
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Job Description

• Takes in info from the environment and translates
  it for the sensory neurons

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Soma

• (cell body)

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Job Description

• Contains the nucleus

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MOTOR CORTEX
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MOTOR CORTEX COVERS THE FRONTAL LOBE AND
CONTROLD VOLUNTARY MOVEMENTS. EXAMPLE
SWALLOWING MUSCLE MOVEMENT(HAND AND FINGERS)


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PREFRONTAL CORTEX
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PERFRONTAL CORTEX IS ALSO FOUND IN THE
FRONTAL LOBES. THIS CORTEX IS INVOLVED IN
PLANNING AND ORGANIZATION, RESPONSE TO REWARD AND
PUNISHMENTS, AND SOME FORM OF DECISION MAKING.
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TEMPORAL LOBE
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THE TEMPORAL LOBE CONTAINS THE AUDIORY CORTEX.
THIS CORTEX RECEIVES AUDITORY INFORMATION FROPM
OUR EARS (HEARING)
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OCCIPITAL LOBE
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OCCIPITAL LOBES ARE WHERE THE VISION CORTEX
CAN BE FOUND. VISUAL CORTEX PROCESSES VISUAL
INFROMATION.
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BASAL GANGLIA
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BASAL GANGLIA WORK TO SMOOTH MOVEMENTS.
(MOTOR CONTROL)
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LSD
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Psychedelic hallucinogenic Stimulates serotonin
receptors, disrupting the brain stems ability to
screen out irrelevant stimuli
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Amphetamines
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Synthetic drugs Speed, crank, ice Increases the
release of dopamine and epinephrine
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Threshold Potential
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-55mV or the point of no return. A stimulus
causes the resting potential to move toward 0mV.
Once -55mV is reached, an action potential will
fire.
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Relative Refractory Period
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The second of the refractory periods. A neuron
will fire during this time, but only with a
stronger than normal stimulus. Playing hard-to-
get.
Miller, 2005
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Absolute RefractoryPeriod
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For a short time after the action potential
happens, it cannot fire again because the sodium
channels will not open.
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All or none law
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An action potential either occurs or it does not
there is no halfway.
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Rate Law
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Intensity of a stimulus is not encoded as size of
an action potential, but by the firing rate.
(Its not the size of the ship its the motion
of the ocean.)
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Steps of the Action Potential
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• Depolarize. Na channels open.
• Threshold up to 30 40 mV.
• Na gates open wide rushes in.
• K gates open K goes SLOWLY
• Action Potential reaches peak.
• Na gates close - ABSOLUTE REFRACTORY.
• 7. K gates wide open.
• 8. K gates close, Na reset.
• 9. NaK pump fixes, cleans resets electrical
  gradient. Excess K flows out of neuron.

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• What is the
• Limbic System?

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Mosby furthermore describes the limbic system to
surround the corpus callosum, as well as parts
of the diencephalon.

• Garrett describes the Limbic system to be, A
  group of forebrain structures arranged around the
  upper brainstem.

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What are the Amygdala?
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The amygdala are two almond-shaped neural
clusters that are components of the limbic system
and are linked to emotion (Myers, 73).

• The amygdala receives input from all the sense
  modalities and produces fear and anxiety by
  targeting a variey of brain structures that
  produce emotional responces (Garrett, 198).
• This assist us to express our emotions through
  our facial expressions.

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What is the Hippocampus?
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The hippocampus is the most inferior structure of
the limbic system that is essential to memory
processing and storage (Meyer, 73).Damage to
the hippocampus impairs the ability to retain new
memories.
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What is the hypothalamus?
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The hypothalamus is the neural structure located
beneath the thalamus and is charged to assist
with governing the endocrine system by means of
the pituitary gland and also linked to emotion
(Meyer, 74).

• The hypothalamus also influences hunger,
  regulates thirst and drives sexual behavior
  (Garrett, 441).