Myelin Nuero Flashcards
MYELIN
HIGH conduction velocity —> transmited down axons —> saltatory conduction of action potencial at the NODES OF RANVIER => are HIGH concentrations of Na channels
MYELIN IN CNS ( including CN II) synthesized by ______
Oligodendrocytes
MYELIN IN PNS ( including CN III-XII) synthesized by _______
Schwann cells
MYELIN _____ and _______ axons
MYELIN wraps and insulates axons
membrane capacitance
LOW (decrease)
Membrane resistance
HIGH (increase)
SPACE CONSTANT (length)
HIGH (increase)
Time constant
LOW (decrease)
Schwann cells promotes _______ and are derived from _______
axonal regeneration / neural crest
Each Schwann (“Shwone”) cell myelinated only _____ PNS axon
1 (one)
Schwann are injured in ____________ syndrome
Guillain-Barre
Schwann cell marker is ______
S100
Anatomy of Schwann cells
Nucleus , Schwann cell , Myelin sheath and Node of Ranvier
Anatomy of Oligodendrocytes
Node of Ranvier, Axon and Oligodendrocyte
Oligodentrocytes are myelinated axons of neurons in _____.
CNS
Each oligodendrocyte can myelinate how much axons (~)?
~30
Oligodendrocytes are a predominantly a type of ____ cell in ______ matter
glial / white
Oligodendrocyte are derived from ___________.
Neuroectoderm
Oligodendrocytes are injure in: ________, ________, and ________.
Multiple sclerosis
Progressive multifocal leukoencephalopathy (PML)
Leukodystrophies
Anatomy of Blood Brain Barrier
Astrocyte foot processes
Capillary lumen
Tight junction
Basement membrane
The function of the BBB is to prevent circulating _________ from reaching the _____ and ______.
blood substances
CSF / CNS
What cross slowly by carrier mediated transport mechanisms in the BBB?
Glucose / amino acids
What cross rapidly via diffusion in the BBB?
Nonpolar / lipid-soluble
What organs allows molecules in the blood to affect brain function or neurosecretory products?
Circumventricular organs with fenestrated capillaries and NO BBB
Examples of NO BBB - area postrema
vomiting after chemotherapy
BBB disruption is an example of _____ which equals _________
stroke / vasogenic edema
What hyporosmolar agents can disrupt the BBB?
Mannitol ( increase permeability of medications)
Sodium channels are ______ enriched in _________ to propagate _______________ via __________ conduction
HIGHLY
NODES OF RANVIER
ACTION POTENTIALS
SALTATORY
Nav. 1.2 in ______ and ______
CNS / PNS
Upon maturation _____ is down regulated, while _____ compensates
Upon maturation NAV1.3 is down regulated, while NAV1.6 compensates
Early myelination: colocalization of ______ and _______ clusters.
Early myelination: co-localization of NAV1.2 and NAV1.6 clusters.
_______ gel electrophoresis of myelin proteins in the presence of _____ (SDS) stained with _____________. The electrophoretic system _______ proteins primarily according to their molecular ______, with the _____ proteins migrating the __________ toward the _____ of the gell.
Polyacrylamide gel electrophoresis of myelin proteins in the presence of sodium dodecyl sulfate (SDS) stained with Coomassie brilliant blue. The electrophoretic system separates proteins primarily according to their molecular size, with the smallest proteins migrating the farthest toward the bottom of the gell.
When does myelination begins?
during the late fetal period and continues during the fist postnatal year
When myelination tends to be functional?
Around the same time the fibers complete to become functional
When does motor fibers tend to become myelinated?
Before sensory fibers
What are myelinated axonal nerves?
White lipid rich insulating membrane that wraps around SOME axonal projections
Myelinated axonal nerves evolved to
1 . _______ the conduction of ______ of ____________ signals between neurons.
2. __________ energy requirements.
Myelinated axonal nerves evolved to
1 . INCREASE the conduction of SPEED of ELECTRICAL signals between neurons.
2. REDUCING energy requirements.
Myelination is completed by specialized _______ cells.
GLIA
CNS (Central nervous system) use _______ and it myelinated as many as ______ axons.
CNS (Central nervous system) use OLIGODENTROCYTES and it myelinated as many as 30 axons.
PNS (Peripheral nervous system) use ______ and it myelinated only _____ neuron.
1 (one)
Myelination of Axonal nerves is a ________ process.
It consist of _______ polarization and _______ and ________ of myelin.
Myelination of Axonal nerves is a MULTISTEP process.
It consist of GLIA polarization and EXPANSION and COMPACTION of myelin.
_______ support axonal energy metabolism
GLIA
_______ linkage of local stacks of ___________ myelin.
GAP JUNCTION / NON COMPACTED
_________________________(SLI) is a ______-truncated ____ shape in the myelin internode that is a specific feature of myelinated nerve fibers formed by _______ in the PNS.
Schmidt-Lanterman incisure (SLI) is a CIRCULAR-truncated CONE shape in the myelin internode that is a specific feature of myelinated nerve fibers formed by SCHWANN CELLS in the PNS.
Schmidt-Lanterman incisure (SLI) funtions as:
1. cytoplasmic ____ connecting the _______ and ______ aspect of the myelin sheath
2. formation and _________ stability of myelin
3. regulation of _____________
4. signal ____________
Schmidt-Lanterman incisure (SLI) funtions as:
1. cytoplasmic CHANNEL connecting the INNER and OUTERMOST aspect of the myelin sheath
2. formation and STRUCTURAL stability of myelin
3. regulation of ADHESION
4. signal TRANSDUCTION
Prior to myelination _____________ are present throughout the axonal membrane at ___ density
SODIUM CHANNELS / LOW
Upon Schwann cells adherence and axonal myelination occurs _____ sodium channel clustering.
> (greater than)
Myelin pathologies
1._______________ (CNS)
2. _______________(PNS)
Multiple sclerosis (MS)
Guillain-Barré syndrome
___________ :chronic disease that damages the nerves in the __________ matter of the _____ and __________.
MULTIPLE SCLEROSIS: chronic disease that damages the nerves in the WHITE matter of the CNS and SPINAL CORD.
Does MULTIPLE SCLEROSIS is involved in peripheral nerves?
Not common, 5%
- In MULTIPLE SCLEROSIS the _________ attacks myelin.
- ______ nerve lesions are common.
- ____________in response to the nerve damage.
- Symptoms are: problems with ________, ________, _______ or _________.
- In MULTIPLE SCLEROSIS the IMMUNE SYSTEM attacks myelin.
- OPTIC nerve lesions are common.
- SCARRING OF TISSUE in response to the nerve damage.
- Symptoms are: problems with MUSCLE CONTROL, BALANCE, VISION OR SPEECH.
___________________ is used as experimental model for investigation of demyelination in the _____.
EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS (EAE)
CNS
________________ and ___________ mechanisms leads to key pathological features of MS: ______________, _______________, ______ loss and ___________ in the CNS.
IMMUNOPATHOLOGY and NEUROPATHOLOGY mechanisms leads to key pathological features of MS: inflammation, demyelination, axonal loss and gliosis in the CNS.
EAE may occur following ________ infections of ____________.
viral infections / vaccinations
Guillain-Barré syndrome is a AUTOIMMUNE disease that attacks the _______ nerve myelin. ____________ cell myelination.
Guillain-Barré syndrome is a AUTOIMMUNE disease that attacks the PERIPHERAL nerve myelin. SCHWANN cell myelination.
Guillain-Barre onset of disorder are ______ and ________.
fear / anxiety
Guillain-Barre symptoms are:
1.
2.
3.
4.
- PAIN
- MUSCLE WEEKNESS
- PARALYSIS
4.WEAKNESS OF BREATH MUSCLES
Guillain-Barre diagnosis include:
1.
2.
3.
4.
5.
- rapid development of muscle paralysis
- absence of reflex
- CSF fluid analysis
- nerve conduction studies
- blood test (not due to low blood K+levels)
