Cytology | ||
Cytology - Health, NeuroDevelopment and Neural Science | ||
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 claudin cadherins | |
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 vitamins | |
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 and 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. | |
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