Neurodevelopment Health Cytology

Question Answer Note/Hint
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
where are electrical synapses found? retina and pacemaking functions (myocardium)
what is a connexon? a connexon is a gap junction made up of 4 connexins
do glia have connexons/electrical synapses b/t eachother yes, why else would i ask?
what invades an ischemic area in a stroke? glia (they dont need O2)
what are the 2 types of glia? macroglia -everything else
microglia -macrophages
embryological origin of microglia? mesoderm (they are macrophages)
2 types of astrocytes, structure, location and function type 1 -short and stubby -in grey matter

type 2 - Long processes -in white matter -form end feet on blood vessels
what is principally responsible for enforcing the blood brain barrier? the astrocytic end feet?
where are radial glial cells cell bodies located? near the ventricles
why is heroin more potent than morphine? heroin is more lipophilic and can therefore cross the BBB more easily
what are 3 of the substances that form the BBB? occludin
what do astrocytes release that cause the formation of new blood vessels in response to ischemia? vacular endothelial growth factor (VEGF)
what substance do type 2 astrocytes release that induces the blood vessels to form tight junctions? angiopoietin-I
what must be given along w/ L-Dopa to allow it to cross the BBB? MAO inhibitors
what substances are actively transported across the endothelial cell in the brain? glucose
amino acids
why can glial tumors be given chemotherapeutic agents w/o worrying about the BBB? they dont have a BBB
why can the loss of one oligodendrocyte in the CNS cause so much damage? an oligodendrocyte may myelinate 50 different axons.
what molecule makes the initial contact b/t the oligodendrocyte processes and the axon in the CNS? MCAM
what molecule anchors adjacent layers of myelin in the CNS? PLP -phospolipid proteins
what molecule anchors adjacent layers of myelin in the PNS? P0 -protein zero
what molecule serves as a spacer b/t adjacent layers of myelin in the CNS and PNS? myelin basic protein -MBP
what is the signal conduction velocity in a myelinated axon? 200 m/s
what determines if an axon will be myelinated in the PNS? the size of the axon
greater than 1/3 micrometer and it will be myelinated
how does a progenitor cell produce either an oligodendrocyte or an astrocyte? the progenitor cell will divide exactly 8 times in the presence of PDGF (platelet derived growth factor)

it has a set number of PDGF receptors and after 8 divisions, it can no longer respond

in the presence of CNTF (cellular neurotrophic factor), the daughter cells will become astrocytes. by default, they become oligodendrocytes
what forms a scar in the CNS when an axon is damaged? astrocytes
what molecules do oligodendrocytes produce that are paralyzing neurites? NOGO
neurite outgrowth factor
when do schwann cells release Ach? when a muscle is denervated, schwann cells will release Ach to stimulate it so it does not atrophy
where does the different regenerative abilities of the CNS and PNS come from? differences in the glia?
where are ERB-2 and ERB-4 receptors expressed? on radial glial cells
what happens to radial glial cells after they stop interacting with neurons they collapse, retract their processes, and become astrocytes or interneurons
how do astrocytes control the potassium concentration in the extracellular space in the brain? they take up K (from lots of AP) with their end feet on nodes of ranvier and dump K into the blood vessels via their end-feet on vessels
how do astrocytes and neurons eat off the same plate? astrocytes take up glucose from epithelial cells and turn it into lactate taking 2 ATP's from the 36. they then deliver lactate to the neuron's far reaching axons, etc.
when the brain swells, which cells are swelling? the glia. the neurons dont swell that much.
Toxicants Neurodevelopment Health 2016