LEc 10 Nevous system

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University of Toronto Scarborough
Biological Sciences
Stefan Rusyniak

Lecture 10 Nervous Systemy Neuron o Large cellsall we really see is cell bodyhave multiple branches really long can account for large amount of volume axon and SA but dont usually see themCell bodyperikaryon surrounds nucleus o Nucleas large and pale thin dark outline central darkly staining nucleus owls eye appearanceCan tell that a lot of genes active high metab activityreq lots of genes need some machinery to convert geneproteincytosol has nissl substance frag of rerCytoplasm basophilic because of the abundant rer and initially called nissl substance because stained with nissl stain Nervous tiossues dont use he nissl stain is a basic staino Neuronmay be super branched but thin cytoplasmic processes cant really show upo Golgi and cajal stain specifically cytoskeletonbrown stain and thats when we see branching of neurono Axonal transportuses microtubules transporting vesicles through axonMolec motors grab vesicle holding NT and bring it down to terminiRetrogradehave dendrites in hand take up the virus travel up to cell body and infect other cells from there Example of retrograde transporty Dorsalcell bodies of sensory neurons Small neurony Bottom ventral horns anterior hornslarge amounts of motor neuronsy Can have another neuron synapsing onto a cell body with unipolar neurons y Bipolar neuronusually interneuron y Pseudostarts as bipolar neuron but axon and dendrite slide down side of cell body and form the pseudo neuron These tend to be sensory neurons and have one end wn a messins corpuscle Receive info about touching stuff send AP transmitted down to axon Cell body doesnt really do anything just maintain fibres o Two fibres afferent and efferent Its the axon hillock thats near terminus axon hillock is region that gen APy Dendrites o Bring info to cell body Travel from tip to body Short cytoplasmic processes can be quite branched tend to have a variable diametertip thin gets wider toward cell body Axon dif unfirom diameter Within dendrite will see staining of nissl substanceDendrites unmyelinated If short fibre dont need to speed up transmission They carry depolarizations not AP Key distinction AP is one that is a constant amount of depolarization Depolarization attenuates over time dies out graded potential actual depol has to reach axon hillock in order to have any action potentialy Make get imp signal sending consistent depolarization temporal summation and then keep replenishing depol before it can die out at axon hillocky Need a threshold of depolarization before AP firesy Soln have more than one point on dendrite receiving this info All same time same msg bigger wave of depol reaches axon hillock y Dendrites increasing SA for reception via dendritic spines
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