Transcript Neuroglia - wsscience

Kaelyn Bildsten
Pat Ladue
Brooke Gainer
 The
supportive tissue of the nervous system
including the network of branched cells in
the central nervous system
 Neuroglia cells also maintain homeostasis
and form myelin
 Neural
support cell that forms the epithelial
lining of the ventricle in the brain and the
central canal of the spinal cord.
 Gives rise to the epithelial layer around the
choroid plexus.
 Glue
between neurons, providing structural
and metabolic support
 Provides nutrients to the nervous tissue
 Maintains extracellular ion balance
 Plays a principal role in repair and scarring of
the brain and spinal cord
 Astroclasts
maintain the blood-brain barrier
 Regulates nutrients and dissolved gas
concentrate
 Absorb and recycle neurotransmitters
 Form scar tissue after bodily injury
 Surround
and insulate the long fibers (the
axons) through which the nerves send their
electrical messages.
 Form the insulation of the axons exclusively
in the CNS
 Structural organization by tying clusters of
neurons together
 Forms
myelin sheath that surrounds axons
structural framework
 Protects axons from subsequent injury:
implications for deficits in multiple sclerosis
 Produced by Schwann cells
 Acts
as insulation to increase the rate of
transmission of signals
 Protects of the nerve fiber
 Formed of protein
 If an axon is severed, the myelin sheath allows the
axon to grow back along the sheath, allowing the
axon to return to normal
 Unmyelinated axons do not regenerate
 Part
of the axon that is myelinated
 Internodes consist of an axon or multiple
axons surrounded by a Schwann cell
 Located
between myelinated segments
 Nodes exist between each Schwann cell along
myelinated axons
 Nodes of Ranvier
 Regions
dominated by myelinated axons
 Myelin has high fat content which cause it to
look white
 Contains
unmyelinated axons
 Makes up a major part of the brain
 Remove
cell debris, waste, and pathogens by
phagocytosis
 Resident macrohages of the brain and spinal
column
 Brain and spinal column considered immune
privileged organs because they are seperated
by the blood-brain barrier
 Clustered
in masses called ganglia
 Satellite cells surround neuron cell bodies in
ganglia
 Schwann cells form a sheath around every
peripheral axon
 Schwann cells also enclose segments of
several unmyelinated axons
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Oligodendrocyte. (2010). In Encyclopædia Britannica. Retrieved February 03, 2010, from Encyclopædia
Britannica Online: http://www.britannica.com/EBchecked/topic/427597/oligodendrocyte
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Ependymal cell. (2010). In Encyclopædia Britannica. Retrieved February 03, 2010, from Encyclopædia
Britannica Online: http://www.britannica.com/EBchecked/topic/189483/ependymal-cell
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Astrocytes help separate man from mouse. (n.d.). Physorg. Retrieved February 3, 2010, from
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Physorg.com website:
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http://www.physorg.com/news157036357.html
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Baumann, N., & Pham-Dinh, D. (n.d.). Biology of Oligodendrocyte and Myelin in the Mammalian Central
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Nervous System . In Physiological Reviews. Retrieved February 3, 2010, from American Physiological
Society website: http://physrev.physiology.org/cgi/content/full/81/2/871
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Neuroglia. (n.d.). The Free Dictionary [Dictionary Entry]. Retrieved February 3, 2010, from

http://medical-dictionary.thefreedictionary.com/neuroglia
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Neuroscience For Kids. (n.d.). Retrieved February 3, 2010, from The Society for Neuroscience website:

http://faculty.washington.edu/chudler/bbb.html
Ion Movement next
The Transmembrane Potential
1. Passive Forces Acting across the Membrane
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Chemical Gradients
Also known as concentration Gradients
Intracellular potassium ion concentration is high which
causes ions to move out of the cell
Sodium ions drive ions into the cell
Chemical gradients are the forces that cause the
movement in and out of the cells
Electrical Gradients
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Potassium ions go through cytoplasm faster than sodium
ions do.
This causes a loss in positive charge and makes for an
excess in negatively charged proteins
Positive and negative charges are seperated by cell
membrane and stops the free movement of ions.
When the positive and negative ions are seperated,
potential difference arises
Current

A movement of charges to eliminate a
potential difference.
Resistance

A measure of how much the membrane
restricts ion movement.
Electrochemical Gradient

Sum of the chemical and electrical forces
acting on that ion across the cell
membrane.
2.Active Forces across the Membrane

Passive Channels (Leak channels)
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Always open.
Permeability changes as channel changes shape
due to the response of proteins to local
conditions.
Ex) Sodium and Potassium leak channels during
a cell’s normal resting potential.
2.Active Forces across the Membrane
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Active Channels
(Gated Channels)
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Activated

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Open or Close in Response to
Specific stimuli.
Open
Inactivated
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
Closed
Cannot be Opened
Active Channels (Gated Channels)

Chemically Regulated Channels

Open or close when specific chemicals bind to
receptor sites.
Ex) Binding of ACh at neuromuscular Junctions
Active Channels (Gated Channels)

Voltage Regulated Channels
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
Open or close in response to changes in
transmembrane potential.
Found in excitable membranes which can
generate and conduct an action potential.
Ex) Voltage regulated sodium, Potassium, and
Calcium channels.
Active Channels (Gated Channels)

Mechanically Regulated Channels

Open or close upon changes along surface of
membrane.
Ex) Sensory receptors that respond to physical
stimuli like touch, pressure, and vibration.
Graded Potentials
Changes in the trans- membrane potential
that cannot spread far from the area
surrounding site of stimulation.
A. Depolarization
1.
2.
3.
4.

The trans-membrane potential is most affected at the
site of stimulation and the effect decreases with
distance.
The effect spreads passively owing to local currents.
The graded potential change may involve either
depolarization or hyperpolarization. The nature of the
change is determined by the properties of the
membrane channels involved.
The stronger the stimulus, the greater the change in the
trans-membrane potential and the larger the area
affected.
Any shift from rest potential toward 0mV
B. Repolarization
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Chemical stimulus is removed in normal
membrane permeability is restored, transmembrane potential returns to resting
Restoring normal resting potential after
depolarization
Combination of ion movement through
membrane channels and the activity of ion
pumps especially sodium and potassium
pumps
C. Hyperpolarization

Rate of potassium outflow increases and the
interior of the cell would lose positive ions.
Hyper polarization in an increase in the
negativity of resting potential.
Action Potentials
Action Potential- The electrical activity developed in
a nerve cell during activity.
1. The All-or-None Principle
Principle states that if a stimulus is strong enough to
generate a nerve action potential, impulse is
conducted along the entire neuron at maximum
strength, unless conduction is altered by conditions
such as toxic materials in cells or fatigue.
All or None Principle

Action Potentials
2.Generation of Action Potential
1. Depolarization to threshold.(-60mv)
2. Activation of sodium channels and
rapid depolarization: Sodium
activation gates open and membrane
becomes permeable to Na⁺.(-60mv
closer to positive)
Action Potentials
3.
Inactivation of sodium channels
and activation of potassium
channels: Voltage regulated
channels open. At +30mv, cytosol
along the interior of the
membrane contains positive
charges. K⁺ is moved out of the cell
and the loss shifts things back to
repolarization.
Action Potentials
4.
The voltage-regulated sodium channels return to normal and
membrane is now able to generate another action potential.
Voltage-regulated potassium pumps begin closing at -70mV.
They do not all close at the same time causing potassium to
continued to be lost and a temporary hyperpolarization
occurs. All voltage-regulated channels close and membrane
returns to resting state at end of refractory period.
3.Propagation of Action Potentials
Continuous Propagation
 Basic mechanism by
which an action potential
is propagated along an
unmyelinated axon.
Saltatory Propagation
 The relatively rapid
propagation of an action
potential between
successive nodes of a
myelinated axon.
Propagation of Action Potentials:
Continuous Propagation
Propagation of Action Potentials: Saltatory
Propagation
Propagation of Action Potentials:
Saltatory Propagation
References
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All-or-none Principle. (n.d.). Brainwave. Retrieved
February 3, 2010, from Brainwave website:
http://library.thinkquest.org/28457/allornone.shtml
Martini, F. H. (1999). Neurophysiology. In Neural
Tissue. Retrieved February 4, 2010, from Prentice Hall,
Inc website:
http://cwx.prenhall.com/bookbind/pubbooks/martini
demo/chapter12/medialib/CH12/html/ch12_5_2.html
Martini, F. H. (2006). Fundamentals of Anatomy and
Physiology (L. Berriman, Ed., 7th ed.). San Francisco,
CA: Pearson Education.
Synapse Activity
Synaptic Activity
By: Josh Llaneza
Mollie Worthington
Logan Michel
Electrical Synapses
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Type of synapse between 2 apposed neurons
Nerve impulse is rapid
Occurs by the passage of ions from one neuron to the
other via the gap junction channels
Can be bidirectional and unidirectional
Used when fast response and coordination of timing is
crucial
 Escape reflexes
 Retina of vertebrates
 Heart rhythm
Chemical Synapses
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1.
2.
3.
4.
5.
6.
Type of synapse that allows a 2 neurons to communicate
or a neuron to communicate with a non-neuronal cell
Action Potential goes down Axon
Calcium pumps open and Calcium diffuses into Axon
Synaptic vesicles are forced to synaptic cleft and release
Acetylcholine
Acetylcholine binds with receptor sites for sodium channel
Sodium is diffused into cell, making the membrane potential more
positive
If the potential reaches threshold level, then an action potential
will be produced
Cholinergic Synapses
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Cholinergic: Relating to nerve cells or fibers that employ
acetylcholine as their neurotransmitter.
Synapses: the site of functional apposition between
neurons, where an impulse is transmitted from one to
another, usually by a chemical neurotransmitter released
by the axon terminal of the presynaptic neuron.
Cholinergic Synapses: synapses with a chemical
neurotransmitter that is made up of acetylcholine.
Acetylcholine: plays an important role both in learning
and memory and in sending messages from motor nerves to
muscles, especially in the heart, bladder and stomach.
Where Can a Cholinergic Synapses
Found?
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All motor neurons activating skeletal muscle
Many neurons of the autonomic nervous system
especially those in the parasympathetic branch
 Parasympathetic: originating in the brain stem and
the lower part of the spinal
cord that stimulate digestive
secretions, slow the heart,
constrict the pupils, and
dilate blood vessels.
Some are found in the central nervous system as well
Other Neurotransmitters


Serotonin: normally involved in temperature
regulation, sensory perception, mood control. Plays a
major role in emotional disorders such as depression,
suicide, impulsive behavior, and aggression.
Norepinephrine: also called noradrenalin; doubles
part-time as a hormone.
 Neurotransmitter = helps to regulate arousal,
dreaming, and moods.
 Hormone = increases blood pressure, constricts blood
vessels and increases heart rate - responses that
occur when we feel stress.
Other Neurotransmitters Cont.
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Glutamate and GABA (gamma-amino butyric acid):
amino acids that act as neurotransmitters. The
majority of synapses within the brain use
glutamate or GABA.
They have other functions in the body like making
energy-rich molecules in cells.
It is likely that they will be altered during drug
addiction.
 This makes it difficult to treat addiction with drug
therapy without causing side effects.
Bibliography
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Cell signaling. (2007). Alzheimer society. Retrieved February 4, 2010,
from
Alzheimer's Association website: http://alzheimer.ca/english/
alzheimer_brain_mini_site/06.htm
Chemical synapse. (2009). Absolute astronomy. Retrieved February
4, 2010, from
http://www.absoluteastronomy.com/topics/Chemical_synapse
Definition of acetylcholine. (n.d.). Medicine net. Retrieved February
3, 2010,
from MedicineNet, Inc. website:
http://www.medterms.com/script/main/
art.asp?articlekey=23278
Electrical synapse. (2009, February 24). Biology online. Retrieved
February 3,
2010, from http://www.biologyonline.org/dictionary/Electrical_synapse
Bibliography Cont.
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McKinley, & O'Loughlin. (n.d.). animation chemical synapse [Video]. Retrieved
from Mcgraw hill website: http://highered.mcgrawhill.com/sites/0072495855/
student_view0/chapter14/animation__chemical_synapse__quiz_1_.html
Millar, N. (2004, June 20). Synapses. In Biology mad. Retrieved February 3,
2010, from
http://www.biologymad.com/master.html?http://www.biologymad.com/
NervousSystem/NervousSystem.htm
Other neurotransmitters. (n.d.). Understanding addiction. Retrieved February
3,
2010, from Addiction Science Research and Education Center, College of
Pharmacy, The University of Texas website:
http://www.utexas.edu/research/
asrec/other_p.html
Synapse. (n.d.). The free dictionary. Retrieved February 3, 2010, from Farlex,
Inc. website: http://medical-dictionary.thefreedictionary.com/
cholinergic+synapse
Information Processing next
Information Processing by
Individual Neurons
Postsynaptic Potentials
Mike Bell
Cassie Mays
Gabby Severs
Postsynaptic Potentials
A
change in the resting potential of a
postsynaptic cell following the stimulation
from a presynaptic cell.
 (The change in a signal receiving cell such as
a muscle cell after a presynaptic cell such as
a motor neuron gives a neurotransmitter)
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Yellow- presynaptic
neuron
Green- postsynaptic cell
Excitatory Postsynaptic potentials
(EPSP)
 These
PSPs increase the likelihood of the
neural message to be turned into an action
from the postsynaptic cell
 They make the membrane of the PS cell
more positive (depolarized) and accelerates
the process to get an action done
Inhibitory Postsynaptic Potentials
(IPSP)
 Opposite
of EPSP
 An electrical charge in the membrane of a
postsynaptic neuron caused by the binding of an
inhibitory neurotransmitter from a presynaptic cell
to a postsynaptic receptor.
 Makes the cell membrane of the PS cell more
negative (hyperpolarized)
 Decreases, halts, the action’s chances of being
completed
•Graph Showing activity in PS cell
•EPSP excites
•IPSP inhibits
Summation
Temporal summation - transmission of
an impulse by a rapid stimulation of
one or more pre-synaptic neurons .
 Spatial summation - transmission of an
impulse by simultaneous stimulation of
two or more pre-synaptic neurons .

The 3 distinct zones
1. Input Zone: the ligand-gated ion channels are activated
by neurotransmitters, or ligands, and secreted by presynaptic
terminals. This activation creates a postsynaptic potential.
2. Integrative Zone: summates the postsynaptic potentials
and initiates an action potential. Action potential depends on
the activation of voltage-gated ion channels.
3. Conductive Zone: then spreads along the action potential.
The postsynaptic potentials require activation of ligand-gated
ion channels on the postsynaptic membrane.
Facilitation

The amount of neurotransmitter released is
not always fixed. If the first action potential
caused more to be released by the second, it
is called facilitation. If less is released, then
its considered depression.
References
Burt, A. M. (n.d.). Synaptic Transmission. In Biology Reference. Retrieved February 4, 2010, from
http://www.biologyreference.com/Se-T/Synaptic-Transmission.html
Excitatory and Inhibitory Postsynaptic Potentials. (2001). Neuro science. Retrieved February 2, 2010, from
Sinauer Associates, Inc. website:
http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=neurosci&part=A477
Giuliodori, M. J., & Zuccolilli, G. (2004). Postsynaptic Potential Summation and Action Potential Initiation.
In Advances in Physiology Education. Retrieved February 4, 2010, from
http://advan.physiology.org/cgi/content/full/28/2/79
Postsynaptic Potential. (2008, March 11). Mondofacto [Online Medical Dictionary]. Retrieved from
http://www.mondofacto.com/facts/dictionary?postsynaptic+potential
Postsynaptic Potentials. (n.d.). Washington University. Retrieved February 2, 2010, from
http://courses.washington.edu/conj/neuron/postsynaptic.htm
Diseases
 The
words are there. Click in the white space
and they will appear. Don’t ask me why!! Has
to do with the formatting. You can always go
to 2nd or 3rd.
What Is Parkinson's Disease?
Parkinson's disease is a brain disorder that
leads to several symptoms that effect the
body such as; shaking, stiffness, and
difficulty with walking, balance, and
coordination. It affects about half a million
people in the United States. The average
age of onset is 60 years, and the risk of
developing Parkinson's goes up with age.
What Causes Parkinson's Disease?
Parkinson's disease occurs when nerve cells, or neurons, in
an area of the brain that controls movement die. Normally,
these neurons produce an important brain chemical known as
dopamine, but when the neurons are affected or die off the
less dopamine is made. This shortage of dopamine causes the
movement problems for the people affected by this disease.
Dopamine is a chemical messenger, or neurotransmitter.
Dopamine is responsible for transmitting signals for multiple
spots in the brain. The connection is critical to produce
smooth, movement.
•Treatment and Research
Although there is no cure for Parkinson's disease, medicines
and surgery can often provide help with dealing with it.
However, these treatments are not very effected sometimes
and scientist are trying to find better ways to treat it. Recent
advances in areas such as genetics, drug therapy, and brain
stimulation offer hope that some day it may be possible to
cure the disease, delay its onset, or prevent it altogether.
•Medications
“Medications for Parkinson's fall into three groups. The first
group includes drugs that increase the level of dopamine in
the brain. The second group affects other neurotransmitters
in the body in order to ease some of the symptoms of the
disease. The third group includes medications that help
control non-motor symptoms (those that do not affect
movement) of Parkinson's.”
•“Surgical Treatments and Other Therapies
Pallidotomy was once the most common surgery for
Parkinson's. In this procedure, a surgeon destroys a portion
of the brain called the globus pallidus. Pallidotomy can
improve symptoms of tremor, rigidity, and bradykinesia,
possibly by interrupting the connections between the globus
pallidus and the striatum or thalamus.”
http://www.buzzle.com/articles/mercury-poisoning-symptoms.html
http://nihseniorhealth.gov/parkinsonsdisease/faq/faq1a.html
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Mercury is odorless, colorless, and tasteless.
Only liquid metal at room temp.
Very toxic.
Used in Thermometers, Barometers, Batteries, and VaporLamps.
Found as a native metal.
Found within cinnabar, corderoite & livingstonite.
Roughly 50% of our supply comes from Spain & Italy.
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Mercury breaks the barrier between blood, and the brain.
Mercury binds to organelles in cells, such as mitochondria,
endoplasmic reticulum, Golgi complex, nuclear envelopes
and lysosomes.
Although very little mercury binds to the nucleus, there is
severe decrease of neuronal RNA and protein synthesis.
Disrupted enzymatic systems in the glycolytic pathway in
the brain.
There are also irregular excitation spikes in mercuryintoxicated neurons.
 Sensory
neurons in the spinal ganglia and
granule cells in the cerebellum are the most
vulnerable to mercury poisoning.
 Causes headaches, vertigo, tinnitus, shaking
in various areas of the body.
 Angry fits, short term memory loss, low self
esteem, inability to sleep, loss of selfcontrol, sleepiness, and difficulty learning.
 Mercury degenerates nerve fibers.
TREATMENTS OF T.S.D ?
 Currently,
there is no cure or effective treatment
for Tay-Sachs.

is a rare
inherited
disorder that
destroys nerve
cells (neurons)
in the brain
and spinal
cord.

Fatty substances
called ganglioside
(GM2) build up in
tissues and nerve cells
in the brain.
This rare
inherited disorder
disease usually
happens to
babies.
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as nerve cells become
distended with fatty
material, a relentless
deterioration of mental and
physical abilities occurs.
The child becomes blind,
deaf, and unable to
swallow. Muscles begin to
atrophy and paralysis sets
in. Other neurological
symptoms include
dementia, seizures, and an
increased startle reflex to
noise.
WHAT IS MULTIPLE SCLEROSIS?
Is an autoimmune
disease
that affects the brain and
spinal
cord(central nervous
system), and as
a result loss of certain
body function
and physical abilities.

HOW DOES M.S AFFECT THE CENTRAL
NERVOUSE SYSTEM ?

It damages the
myelin sheath, the
material that
surrounds and
protects your nerve
cells.
M.S MAKE A PERSON HAVE:
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Visual disturbances
Muscle weakness
Trouble with coordination and balance
Thinking and memory problems
And since it affects your spinal cord
you can be paralyzed.
TREATMENTS OF M.S?
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At this time there is no cure for M.S.
The goal is to use medication which
will slow the progression of multiple
sclerosis which are: (Avonex,
Betaseron, or Rebif), monoclonal
antibodies(Tysabri), glatiramer acetate
(Copaxone),
Sources (to be cited)
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Picture of Mercury. [Data file]. (n.d.). Retrieved from
http://www.periodictable.com/Samples/080.14/
s13.JPG
W, C. L. (1977). Neurotoxic effects of mercury: a review. Unpublished
raw data, Univ. of Arkansas
Medical School, Little Rock. Retrieved from Energy Citations
Database.
Facts about Mercury [Fact list]. (n.d.). Retrieved from facts-about
website:
http://www.facts-about.org.uk/science-element-mercury.htm
Pakhare, J. (2007, May 5). Mercury Poisoning Symptoms [Facts].
Retrieved from Buzzle website:
http://www.buzzle.com/articles/mercury-poisoning-symptoms.html
http://nihseniorhealth.gov/parkinsonsdisease/faq/faq1a.html