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100 Cards in this Set
- Front
- Back
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What percentage of your energy is used by your brain?
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40%
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What type of stain is specific for myelin?
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Hiedenheim Stain
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Which cell type is larger in general? Neuron or Glial
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Neuron
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Of the 10^13 cells in the brain, what percentage are neurons and what percentage are glial cells?
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1. 10-20% Neurons
2. 90-80% Glial |
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What percentage of space do neurons and glial space take up respectively?
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50%
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What percentage of the brain is extracellular space? In cc's?
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15% or 250cc
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As dendrites branch more and more, what happens to their diameter?
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It gets smaller.
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As an axon extends farther and farther, what happens to its diameter?
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It doesn't change.
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What manner is information collected by a neuron transmitted?
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In a graded fashion
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Dendrite information propagation is (Active/Passive)?
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Passive
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What is concentrated at Nodes of Ranvier?
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Sodium Channels
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The fastest neuron transmits signals up to what frequency?
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300Hz
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Half the energy used by the CNS is used for what?
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Maintaining ion concentrations after action potentials (Na/K pump)
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Almost all of a neuron's cell membrane is where?
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Dendrites
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What specific type of cell never uses axons?
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Retinal amacrine cells
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What type of cell has a fusion of the dendrite and the axon?
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Pseudounipolar neuron
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How much of the cell body does the nucleus take up?
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1/3
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How many genes make up the CNS set of genes?
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5000
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The outermost nuclear membrane is continuous with what?
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The ER
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Where does post-transcriptional modification take place in the cell?
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The Golgi
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What part of a neuron will you find the highest levels of mitochondria?
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The nodes of ranvier
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The cytoskeleton of a neuron typically contains what three types of fibers?
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1. Neurofilaments
2. Microfilaments 3. Microtubules |
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What is the substrate for axonal transport?
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Microtubules
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What does the drug Vincristine do? What is it used for?
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It interferes with microtubule formation. This drug is used to fight cancerous tumors.
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What is a side-effect of Vincristine?
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Tingling in the extremities
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How fast is bulk flow of material down an axon?
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1 mm/day
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How fast is microtubule flow down an axon?
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40 mm/day
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What is delivered to the cell body by way of retrograde transport? What do they let the cell body know?
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1. Neurotrophic factors
2. All is well |
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The cell nucleus will only replenish what type of NT?
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Neuropeptides
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What protein is associated with Alzheimers?
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Tau
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Most excitatory synapses are found where?
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Dendritic spines
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What do spines contain?
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Actin and myosin; contractile
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What about your neurons is abnormal in Rett or Down syndrome?
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Abnormal dendritic spines
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Are chemical synapses unidirectional or bidirectional?
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Unidirectional
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Which faster, chemical synapse or an electrical synapse?
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Electrical synapse
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Are electrical synapses unidirectional or bidirectional?
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Bidirectional
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How large is the gap between two cells (connexons)?
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4nm
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What types of materials pass through connexons?
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Second messangers, ions and macromolecules
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All spaces not occupied by neurons or blood vessels are occupied by what?
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Glial cells
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Are glial cells polar? Are they signaling cells?
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No and No
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A lot of healing in the CNS and PNS is due to what?
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Scarring of glial cells
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The symbiotic relationship between what two cells is very important to the CNS?
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Glial cells and Neurons
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Glial cells get their energy through what process?
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Glycolysis - anaerobic respriration
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How many glial cells are their per neuron in a human?
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10 per neuron
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What are the two broad categories of glial cells?
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Microglial and Macroglial
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What are microglial cell's derived from?
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Mesoderm; macrophages
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What are macroglial cells derived from?
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neuroectoderm
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What are the two type of astrocytes?
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1. Type I: associated with grey matter
2. Type II: Fibrous astrocytes - associated with white matter |
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What are the two type myelin-forming cells?
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1. Oligodendrocytes - CNS
2. Schwann Cells - PNS |
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What is the only glial cell associated with the PNS?
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Schwann Cell
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What can be said of the domains of astrocytes?
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They are non-overlapping
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What type of glial cells are very important in neurodevelopment?
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Radial glial cells
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How do fibrous astrocytes usually terminate?
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Endfoot on a vessel
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What is the astrocyte's job in relation to the BBB?
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It reinforces the BBB but is not the BBB.
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What is the purpose of the BBB?
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Protect the brain from toxins.
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What molecules pass freely through the BBB?
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1. Gases with a high partition co-efficient
2. Lipophilic molecules |
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Why do addicts use heroin instead of morophine?
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It is a more lipophilic derivative so it crosses the BBB more efficiently.
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What three adhesion molecules help form the BBB?
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Occludin, Claudin and Cadherin
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What factor is released by astrocytes to induce new vessel growth?
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Vascular Epithelial Growth Factor (VEG-F)
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What two substances do astrocyte end-feet release?
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VEG-F and Angiopoietin
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What does Angiopoietin do?
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Induces the formation of the BBB
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What is an intracellular defense mechanism of an endothelial cell?
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Enzymes that can degrade substances attempting to cross the BBB.
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Name three substances that are actively transported across the BBB?
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1. Glucose
2. AA 3. Vitamins |
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What is a way to transiently open the BBB?
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Osmotic shock
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What is an example of a disease that transiently opens the BBB?
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Meningitis
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How many neurons can be associated with one oligodendrocyte?
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50
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What is an example of a demyelinating disease?
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Multiple sclerosis
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Why are there so many neurons associated with one oligodendrocyte?
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Space saving technique
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The initial contact between the oligodendrocyte and the axon is mediated through what class of adhesion molecules?
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MCAM
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What molecule glues layers of myelin together?
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Phospholipid proteins
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What are the spacer molecules associated with myelin sheaths?
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Myelin Basic Protein
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What is the conduction velocity of a neuron?
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200 m/s
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How many Schwann cells are associated with each axon in the PNS?
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1
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What factors are involed in whether or not a fiber will be myelinated or not?
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1. Axon length
2. Sensory or not 3. Axon diamter |
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What size is the determining factor in axon myelination?
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1/3 of a micron
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What substance can be used to try and overcome an unmyelinated portion of an axon? How does it work?
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4-aminopyridine; blocks K channels
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Is it important to get all 50 wrappings of myelin around an axon for function?
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No, only the first few wrappings are key.
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How many times do the stem cells in the brain divide? What controls the divisions?
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8 times; the number of PDGF on the surface of the cell
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What substances causes a brain stem cell to differentiate into an astrocyte?
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CNTF
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What is a reason that neuron growth is difficult after injury in the CNS?
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Scar formation due to astrocytes.
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What two substances do oligodendrocytes release to supress regrowth of neurons?
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NOGO and Neurite Outgrowth Factor
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What prevents the atrophy of muscle cells after PNS damage?
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Schwann cells release Ach to prevent atrophy
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What two things can radial glial cells turn into when they are done?
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Interneurons and astrocytes
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What are three functions of astrocytes in their contact spacing domain?
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1. K regulation
2. Cleaning up Glutamate 3. Providing lactate (after they use the glucose for energy in glycolysis) to neurons |
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Does the brain exhibit functional or structural regeneration?
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Functional
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Which are thinner? Dendrites or axons?
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Axons
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At what point is the decision made to fire or not fire an AP in a nueron?
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Axon Hillock
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What acts as filter sites for things such as MTs and NTs?
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Axons
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How many membranes does the nucleus have?
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2
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Does the brain exhibit functional or structural regeneration?
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Functional
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Which are thinner? Dendrites or axons?
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Axons
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At what point is the decision made to fire or not fire an AP in a nueron?
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Axon Hillock
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What acts as filter sites for things such as MTs and NTs?
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Axons
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How many membranes does the nucleus have?
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2
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Does the brain exhibit functional or structural regeneration?
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Functional
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Which are thinner? Dendrites or axons?
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Axons
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At what point is the decision made to fire or not fire an AP in a nueron?
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Axon Hillock
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What acts as filter sites for things such as MTs and NTs?
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Axons
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How many membranes does the nucleus have?
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2
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How fast does a neuron going to muscle fibers regenerate?
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1 mm/day
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