Transcript Neuroglia - wsscience

Neuroglia
of the Central Nervous System
Ally, Gina, & Rocky
http://www.wordnik.com/words/neuroglia/pronunciations#
Neuroglia
 Supportive tissue of the nervous system,
including the network of branched cells:
Ependymal
Astrocytes
Oligodendrocytes
Microglia
Ependymal Cells
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Protective layer that lines the brain
ventricles and the central canal of the
spinal cord
Assists in producing, circulating, and
monitoring of cerebrospinal fluid
Epedyma in adults contains stem cells that
can divide to produce additional neurons
Astrocytes
Largest and most numerous
neuroglia in the central nervous
system
Functions
 Maintains the blood-brain barrier
–Isolates the central nervous system
from the general circulation
 Guides neuron development
 Repairs damaged neural tissue
 Adjusts the composition of interstitial
fluid
Oligodendrocytes
 Neuroglia that maintains cellular
organization within gray matter and
provide a myelin sheath in areas of white
matter
Myelin
•Insulation around an axon
•Consists of multiple layers
•Increases impulse rate of the axon
Internodes
– Relatively large areas of the axon that is
wrapped in myelin
Nodes
– Small gaps that separate internodes
White matter
– Regions of the central nervous system
dominated by myelinated axons
Gray matter
– Region of the central nervous sytem
dominated by neuron cell bodies,
neuroglia, and unmyelinated axons
Microglia
 First form of immune for the central
nervous system
 20 percent of the total glial population in
the brain
 Many fine branches
 Capable of migrating through neural tissue
Microglia
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Appear in embryonic development
Janitors of the central nervous system
They remain isolated in the neural tissue
Least numerous and smallest Neuroglia in
the CNS
 Originate from blood cells
Works Cited
The free dictionary. (n.d.). Neuroglia. Retrieved February 4, 2010, from
http://medical-dictionary.thefreedictionary.com
Hybrid medical animation. (n.d.). Glial cells. Retrieved February 4,
2010, from
http://www.hybridmedicalanimation.com
Martini, F. H. (n.d.). Chapter 12. In Fundamentals of anatomy &
physiology (Seventh ed., pp.
384-386). Daryl Fox. (Original work published 2006)
The nervous system [French Multipule Sclerosis Research Society].
(n.d.). Retrieved February 4,
2010, from http://images.google.com
Neuroglia. (n.d.). Pronunciation. Retrieved February 4, 2010, from
http://www.worknik.com
Ion movement next
Ion Movements and
Electrical Signals
By: Caitlin, Drake, Lizzy, Jaylen
Passive Forces Acting Across the
Membrane
 Chemical gradients- Drive sodium ions into the
cell.
 Electrical gradients- Potassium ions leave the
cytoplasm more rapidly than sodium ions enter.
 Current- A movement of charges to eliminate a
potential difference.
 Resistance- A measure of how much the
membrane restricts ion movement.
 Electrochemical gradient- The sum of the chemical
and electrical forces acting across the cell
membrane for a specific ion.
Active Forces Across the Membrane
 Passive channelsMembrane channels that
are always opened but
their permeability varies
time to time
 Active ChannelsMembrane channels that
open or close when
responding to a stimuli,
they are activated when
opened and inactivated
when closed, there are 3
types
Types of Active channels
 Chemical- open or
close to specific
chemicals
 Voltage- open or close
according to changes
in charges along the
membrane
 Mechanical- Open or
close according to
physical distortions
Graded Potentials
 Impulses that cannot travel far from the site
of stimulation. “Local Stimulation”
Depolarization- any shift from negative
resting potential towards 0mV.
 NA+ ions enter the cell to make it less
negative
 As a result the impulse is sent.
Repolarization- process of restoring the cell
back to its normal resting potential. The cell
becomes more negative.
Graded Potentials Continued
 Hyperpolarizationcell temporarily
becomes more
negative than its
resting potential.
 Occurs because too
much K+ has leaked
out of the cell.
 Nerve cannot be
stimulated until its
back to its resting
potential.
Action Potentials
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impulses that travel long distances quickly.
All-or-None Principle- once the nerve cell
is depolarized past the threshold level the
impulse is sent.
If it doesn’t reach the threshold, the
impulse is not produced.
Stimulus either triggers an action potential
or it doesn’t. There is no in-between.
Generation of Action
Potentials
 Step 1: depolarization of nerve cell to threshold
level.
 Step 2: NA+ channels open and NA+ ions enter
the cell. Creates rapid depolarization.
 Step 3: NA+ channels close and K+ channels
open. K+ ions exit the cell. This starts
repolarization.
 Step 4: Hyperpolarization occurs because too
much K+ ions leaked out of the cell. Once the K+
channels are shut, normal resting potential is reestablished.
Action Potential
Propagation of Action Potentials
 propagation- how the impulse travels.
 Continuous Propagation- occurs on
unmyelinated axons, impulse slowly travels
down the axon.
 Saltatory Propagation- on myelinated
axons, impulse jumps from node to node.
This is much faster than continuous
propagation.
Works Cited
 "Action Potential." Harvard Outreach Animations. Web. 4 Feb. 2010.
<http://outreach.mcb.harvard.edu/animations/actionpotential.swf>.
 Human Physiology. Web. 4 Feb. 2010.
<http://people.eku.edu/ritchisong/301notes2.htm>.
 Matthews, Gary G. "NEUROBIOLOGY." Nuerobiology Animations.
Web. 4 Feb. 2010.
<http://www.blackwellpublishing.com/matthews/animate.html>.
 Neuroscience For Kids. Web. 4 Feb. 2010.
<http://faculty.washington.edu/chudler/neurok.html>.
 Society for Neuroscience. Web. 4 Feb. 2010. <http://www.sfn.org/>.
Synaptic activity
Synaptic Activity
Ashleigh Stagg
Kevin Williams
Kelsey Coulter
Synaptic Activity
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Electrical Synapses
Chemical Synapses
Presynaptic- source of action potential
Postsynaptic- Receiving action Potential
Electrical Synapses
 Present in some areas of brain
 Gap junction- current flows through
intercellular channels
 Membrane’s potential is changed inhibiting
or generating action potential
 faster response time
Chemical Synapses
 Transmit impulses in 1 direction to a specific
location
 Fatigue
 Synaptic cleft- no intercellular connectivity
 Synaptic vesicles
 release
neurotransmitters
Process of Chemical Synapses
 Action Potential arrives and depolarizes
synaptic knob
 Calcium enters synaptic cleft triggering the
release of acetylcholine
 Acetylcholine binds to receptors and
depolarizes the postsynaptic membrane
 Initiates action potential
 Acetylcholine is removed through acetyl
cholinesterase
Cholinergic Synapses
 Cholinergic system
includes nerve cells
that produce the
neurotransmitter
acetylcholine
 Acetylcholine is a
chemical the brain
needs to process
information and to
function normally
Cholinergic cont.
 Low acetylcholine levels can lead to
Alzheimer’s disease
Neurotransmitters
 There are nine chemical compounds
belonging to 3 chemical families.
 3 chemical families; Amines, Amino Acids,
Peptides.
 Chemical released by neurons to stimulate
neighboring neurons, allowing impulses to
be passed from one cell to the next
throughout the nervous system.
Amines
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Contains carbon, hydrogen, and nitrogen.
Chemical compounds:
Acetylcholine
Norepinephrine
Dopamine
Seratonin
Amino Acids
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Chemical compounds:
Glycine
Glutamic acid
Aspartic acid
Gamma-amino butyric acid
Peptides
 Contain at least two amino acids
 Chemical Compounds:
 Substance P
Works Cited
 http://faculty.washington.edu/chudler/genet.
html
 http://www.elmhurst.edu/~chm/vchembook/6
62cholinergic2.html
 www.thehormoneshop.com/neurotransmitter
s.htm
Information Processing next
Melanie
H.
Dezeray
H.
Oscar R.
 Neurons carry out
operations that
extract information
from sensory
receptor.
 Neurons translate
this information into
action, imagery and
memory.
 Postsynaptic
potentials are
graded potentials
that develop in the
postsynaptic
membrane in
response to a
neurotransmitter.
 There are two major
types.
 definition- an electrical change
(depolarization) in the membrane of a
presynaptic neuron caused by the binding of
an excitatory neurotransmitter from a
postsynaptic cell to a postsynaptic receptor,
making it easier for action potential to
generate.
 there is a temporary
depolarization of the
postsynaptic
membrane
 they are caused by
positively charged
ions
 when the positively
charged ions reach
the postsynaptic cell,
sensitive
 there can be multiple
of these which can
cause currents and
then go into
summation
 EPSP increases the
chance of an action
potential
 During EPSP Na+
(sodium) flows into
the synaptic knob
causing
depolarization (on
the left)
 an electrical charge (hyperpolarization) in the
membrane of a postsynaptic neuron caused
by the binding of an inhibitory
neurotransmitter from a presynaptic cell to a
postsynaptic receptor; makes it more difficult
for a postsynaptic neuron to generate an
action potential
 presynaptic neurons
releases
neurotransmitters
and bind to
postsynapic
receptors
 ions channels open
and close
 electrical currents
begins and creates
a negative
postsynaptic
 postsynaptic cells
are inhibited and
then it goes into
summation
 IPSP decreases
the chance of an
action potential
 During IPSP K+
(potassium) flows
out of the synaptic
knob causing
hyperpolarization
(on the right)
 Summation is the
ability of skeletal
muscle to contract
at varying degrees
or strength.
 There are two types
of summation:
– Temporal
Summation (motor
unit)
– Spatial Summation
(wave)
 Temporal summation is transmission of an
impulse by rapid stimulation of one or more
pre-synaptic neurons.
 This stimulation transfers to a motor unit,
thus the more motor units stimulated the
stronger the contraction.
 Spatial summation is transmission of an
impulse by simultaneous or nearly
simultaneous stimulation of two or more presynaptic neurons.
 The muscle is stimulated due to frequency
strength is increased because the muscle
has a small amount of time to relax, thus
keeping calcium in sarcoplasm while
putting in more calcium.
 Facilitation- a neuron that is closer to
threshold is said to be facilitated.
 The larger the degree of facilitation, the
smaller the additional stimulus needed to
trigger an action potential

About."Excitatory Postsynaptic Potential."Qkport. Feb.3,2010,
http://www.answers.com/e/excitatory_postsynaptic_potential

Human Physiology- Nuerons and Nervous System. (n.d.). Retrieved February 3, 2010, from
Human Physiology: http://people.eku.edu/ritchisong/301notes2.html

Lefers, Mark."Excitatory Postsynaptic Potential (EPSP)." Northwestern. Feb.4,2010,
http://www.biochem.northwestern.edu/holmgren/Glossary/Definitions/Def_E/ESPS.html

Prentice Hall Inc. (n.d.). Chapter 12 Neural Tissue. Retrieved February 3, 2010, from
http://cwx.prenhall.com/bookbind/pubbooks/martinidemo/chapter12/medialib/CH12/html/ch12_7
_1.html
Silvia Helena Cardoso, P. (n.d.). Communication Between Nerve Cells. Retrieved February 3,
2010, from Fundamentals:
http://images.google.com/imgres?imgurl=http://www.cerebromente.org.br/n12/fundamentos/neur
otransmissores/epsp1a.jpg&imgrefurl=http://www.cerebromente.org.br/n12/fundamentos/neurotr
ansmissores/neurotransmitters2.html&usg=__7lR3lt8Wb2sQiWX7pKCqH7cM0UY=&h=17


Sinauer Associates Inc."Excitatory and Inhibitory Postsynaptic Potential." Feb.3,2010,
http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=neurosci&part=A477

Teach the Brain News. (n.d.). Retrieved February 4, 2010, from Teach the Brain:
Diseases next
VIII Diseases and
Conditions
Mary Tieko
Austin Brown
Anatomy
Period 3
Multiple Sclerosis
•Also known as MS, Attacks the central nervous system,
damage to the myelin sheath that covers nerve cells, then
inflammation causes nerve damage
•Mild: Numbness in limbs
•Severe: Paralysis, loss of vision
•Progression is unpredictable
•Unknown Cause, most likely Immunological (autoimmune)
•Possibly environmental, genetic, or infectious
•No cure
Tay-Sachs
 Genetic disease
 Most common in newborn babies, apparent in the first
few months of life
 The fat Ganglioside builds up in tissues and nerve cells
in the brain
 Tay-Sachs is causes the insufficient activity of
betahexosaminidase A, which speeds up biodegrading
of Ganglioside
 Causes blindness, deafness, and inability to swallow
 No treatment
 Death by 4 years old
Parkinson: Causes
 Causes are currently
unknown
 theories for causes are
oxidative damage,
environmental toxins,
genetics and accelerated
aging
 2005 researchers discovered
a single mutation in
Parkinson gene (first
indentified in 1997) which is
believed responsible for 5
percent of inherited genes.
 Parkinson is slowly
progressive condition
resulting from a deficiency in
the brain of a chemical called
dopamine
 Lack of dopamine
(neurotransmitter)
 Without it, messages from
the brain to the muscles are
disrupted
Common symptoms
 Tremor or involuntary and
rhythmic movement of hands,
arms legs and jaw
 Muscle rigidity or stiffness of
limbs
 Unsteady walk or balance
 Gradual loss of sudden
movement which often leads to
decreased mental sill or reaction
time, voice changes, deceased
facial expression
Diagnosis
 No x-ray or blood test to confirm
the disease
 Positron emission tomography
(pet can support a physician
diagnosis)
 Show of two or more primary
symptoms
 Absence of other neurological
sign upon examination
 Responsiveness to Parkinson
such as levodopa
Treatment
 Dopamine precursors, such
as Levodopa, are
substances that are
converted into dopamine
by an enzyme in the brain
 Dopamine agonists activate
dopamine receptors directly
 Anticholinergics act to
decrease the activity often
the neurotransmitter
acetylcholine
Surgery
 Neurosurgeons can relieve the
involuntary movements of
conditions like Parkinson’s by
operating on the deep brain
structures involved in motion
control
 Deep Brain Stimulation effective
in treating symptoms of
Parkinson disease and allows
significant decrease in
medication doses
 Thalamotomy can help stop
tremor by placing a small lesion
in a specific nucleus of the
thalamus.
What is Mercury?
 A metal that has been used in products such as
light bulbs, batteries, paint, thermometers
 Several forms of mercury such metallic mercury,
organic mercury and inorganic mercury can be
deadly
 Different types of mercury affect people in different
ways
 Organic mercury ids more dangerous than
inorganic mercury
People Expose to Mercury
 Breath mercury fumes
 Eat food with mercury such as fish or drink water
contaminated by mercury
 Eat object that contain mercury such as batteries
 Object made with mercury during manufacture of
product
 For example before 1990 paint was made with
mercury
Affect on Nerves System
 Protein inhabitation
 Disruption of
mitochondrion function
 Direct affect on ion
exchange in a neuron
 Disruption of
neurotransmitter
 Destruction of the
structural framework of
neurons
 effect brain development
by prevent neurons from
finding their appropriate
 Visual cortex
Symptoms
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Resemble symptoms of cereals palsy
Movement abnormities
Convulsion
Visual problem
Abormal reflexes
Sources
 Mercury. (10, 7th, 09). Retrieved from
http://www.epa.gov/hg/effects.htm
 Mercury poisoning . (n.d.). Retrieved from
http://encyclopedia2.thefreedictionary.com/Mer
cury+poisoning,+nervous+system
 Parkinson’s disease facts. (n.d.). Retrieved
from
http://www.smmmc.org/clinicalservices/parkins
ons/facts.shtml
Cont.
 About MS: National MS Society,
http://www.nationalmssociety.org/aboutmultiple-sclerosis/index.aspx
 Tay-Sachs Disease: National Institutes of
Health,
http://www.ninds.nih.gov/disorders/taysachs/
taysachs.htm