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100 Cards in this Set

  • Front
  • Back
What percentage of your energy is used by your brain?
40%
What type of stain is specific for myelin?
Hiedenheim Stain
Which cell type is larger in general? Neuron or Glial
Neuron
Of the 10^13 cells in the brain, what percentage are neurons and what percentage are glial cells?
1. 10-20% Neurons
2. 90-80% Glial
What percentage of space do neurons and glial space take up respectively?
50%
What percentage of the brain is extracellular space? In cc's?
15% or 250cc
As dendrites branch more and more, what happens to their diameter?
It gets smaller.
As an axon extends farther and farther, what happens to its diameter?
It doesn't change.
What manner is information collected by a neuron transmitted?
In a graded fashion
Dendrite information propagation is (Active/Passive)?
Passive
What is concentrated at Nodes of Ranvier?
Sodium Channels
The fastest neuron transmits signals up to what frequency?
300Hz
Half the energy used by the CNS is used for what?
Maintaining ion concentrations after action potentials (Na/K pump)
Almost all of a neuron's cell membrane is where?
Dendrites
What specific type of cell never uses axons?
Retinal amacrine cells
What type of cell has a fusion of the dendrite and the axon?
Pseudounipolar neuron
How much of the cell body does the nucleus take up?
1/3
How many genes make up the CNS set of genes?
5000
The outermost nuclear membrane is continuous with what?
The ER
Where does post-transcriptional modification take place in the cell?
The Golgi
What part of a neuron will you find the highest levels of mitochondria?
The nodes of ranvier
The cytoskeleton of a neuron typically contains what three types of fibers?
1. Neurofilaments
2. Microfilaments
3. Microtubules
What is the substrate for axonal transport?
Microtubules
What does the drug Vincristine do? What is it used for?
It interferes with microtubule formation. This drug is used to fight cancerous tumors.
What is a side-effect of Vincristine?
Tingling in the extremities
How fast is bulk flow of material down an axon?
1 mm/day
How fast is microtubule flow down an axon?
40 mm/day
What is delivered to the cell body by way of retrograde transport? What do they let the cell body know?
1. Neurotrophic factors
2. All is well
The cell nucleus will only replenish what type of NT?
Neuropeptides
What protein is associated with Alzheimers?
Tau
Most excitatory synapses are found where?
Dendritic spines
What do spines contain?
Actin and myosin; contractile
What about your neurons is abnormal in Rett or Down syndrome?
Abnormal dendritic spines
Are chemical synapses unidirectional or bidirectional?
Unidirectional
Which faster, chemical synapse or an electrical synapse?
Electrical synapse
Are electrical synapses unidirectional or bidirectional?
Bidirectional
How large is the gap between two cells (connexons)?
4nm
What types of materials pass through connexons?
Second messangers, ions and macromolecules
All spaces not occupied by neurons or blood vessels are occupied by what?
Glial cells
Are glial cells polar? Are they signaling cells?
No and No
A lot of healing in the CNS and PNS is due to what?
Scarring of glial cells
The symbiotic relationship between what two cells is very important to the CNS?
Glial cells and Neurons
Glial cells get their energy through what process?
Glycolysis - anaerobic respriration
How many glial cells are their per neuron in a human?
10 per neuron
What are the two broad categories of glial cells?
Microglial and Macroglial
What are microglial cell's derived from?
Mesoderm; macrophages
What are macroglial cells derived from?
neuroectoderm
What are the two type of astrocytes?
1. Type I: associated with grey matter

2. Type II: Fibrous astrocytes - associated with white matter
What are the two type myelin-forming cells?
1. Oligodendrocytes - CNS
2. Schwann Cells - PNS
What is the only glial cell associated with the PNS?
Schwann Cell
What can be said of the domains of astrocytes?
They are non-overlapping
What type of glial cells are very important in neurodevelopment?
Radial glial cells
How do fibrous astrocytes usually terminate?
Endfoot on a vessel
What is the astrocyte's job in relation to the BBB?
It reinforces the BBB but is not the BBB.
What is the purpose of the BBB?
Protect the brain from toxins.
What molecules pass freely through the BBB?
1. Gases with a high partition co-efficient
2. Lipophilic molecules
Why do addicts use heroin instead of morophine?
It is a more lipophilic derivative so it crosses the BBB more efficiently.
What three adhesion molecules help form the BBB?
Occludin, Claudin and Cadherin
What factor is released by astrocytes to induce new vessel growth?
Vascular Epithelial Growth Factor (VEG-F)
What two substances do astrocyte end-feet release?
VEG-F and Angiopoietin
What does Angiopoietin do?
Induces the formation of the BBB
What is an intracellular defense mechanism of an endothelial cell?
Enzymes that can degrade substances attempting to cross the BBB.
Name three substances that are actively transported across the BBB?
1. Glucose
2. AA
3. Vitamins
What is a way to transiently open the BBB?
Osmotic shock
What is an example of a disease that transiently opens the BBB?
Meningitis
How many neurons can be associated with one oligodendrocyte?
50
What is an example of a demyelinating disease?
Multiple sclerosis
Why are there so many neurons associated with one oligodendrocyte?
Space saving technique
The initial contact between the oligodendrocyte and the axon is mediated through what class of adhesion molecules?
MCAM
What molecule glues layers of myelin together?
Phospholipid proteins
What are the spacer molecules associated with myelin sheaths?
Myelin Basic Protein
What is the conduction velocity of a neuron?
200 m/s
How many Schwann cells are associated with each axon in the PNS?
1
What factors are involed in whether or not a fiber will be myelinated or not?
1. Axon length
2. Sensory or not
3. Axon diamter
What size is the determining factor in axon myelination?
1/3 of a micron
What substance can be used to try and overcome an unmyelinated portion of an axon? How does it work?
4-aminopyridine; blocks K channels
Is it important to get all 50 wrappings of myelin around an axon for function?
No, only the first few wrappings are key.
How many times do the stem cells in the brain divide? What controls the divisions?
8 times; the number of PDGF on the surface of the cell
What substances causes a brain stem cell to differentiate into an astrocyte?
CNTF
What is a reason that neuron growth is difficult after injury in the CNS?
Scar formation due to astrocytes.
What two substances do oligodendrocytes release to supress regrowth of neurons?
NOGO and Neurite Outgrowth Factor
What prevents the atrophy of muscle cells after PNS damage?
Schwann cells release Ach to prevent atrophy
What two things can radial glial cells turn into when they are done?
Interneurons and astrocytes
What are three functions of astrocytes in their contact spacing domain?
1. K regulation
2. Cleaning up Glutamate
3. Providing lactate (after they use the glucose for energy in glycolysis) to neurons
Does the brain exhibit functional or structural regeneration?
Functional
Which are thinner? Dendrites or axons?
Axons
At what point is the decision made to fire or not fire an AP in a nueron?
Axon Hillock
What acts as filter sites for things such as MTs and NTs?
Axons
How many membranes does the nucleus have?
2
Does the brain exhibit functional or structural regeneration?
Functional
Which are thinner? Dendrites or axons?
Axons
At what point is the decision made to fire or not fire an AP in a nueron?
Axon Hillock
What acts as filter sites for things such as MTs and NTs?
Axons
How many membranes does the nucleus have?
2
Does the brain exhibit functional or structural regeneration?
Functional
Which are thinner? Dendrites or axons?
Axons
At what point is the decision made to fire or not fire an AP in a nueron?
Axon Hillock
What acts as filter sites for things such as MTs and NTs?
Axons
How many membranes does the nucleus have?
2
How fast does a neuron going to muscle fibers regenerate?
1 mm/day