Neurons and Glia Flashcards
Reticular Theory
Golgi - membrane of neurons is fused together; material flows from one to the next
Golgi
famous for Golgi stain - you can see the morphology of selectively stained individual neurons
Neuron Doctrine
Cajal - points of contact; that’s where the cells communicate with each other
Flow of info thru a neuron
Info comes in thru dendrite →
is integrated in the soma →
goes out thru axon to next neuron
Dendrites
excitatory contact, contacts that will make neuron more electrically excitable
Inhibitory synapse
goes right on dendrite, no spine
Excitatory synapse
presynaptic axon terminal touches postsynaptic spine
Axons vs. Dendrites
Axons:
- longer
- thinner
- fewer branches
- uniform diameter (important for AP propagation)
Dendrites:
- shorter
- thicker
- highly branched
- tapered
Microfilament
Actin
small
dynamic, involved in growth and movement
enriched in spines (very dynamic amoeba-like and searching for presynaptic partner)
Neurofilaments (intermediate filaments)
medium
controls thickness of neurites
particularly enriched in axons
Microtubules
large
runs down the length of neurites to give basic shape, acts as a “railroad” for transport proteins
Axoplasmic Transport
Anterograde:
- soma → axon
- Motor protein = kinesin
Retrograde
- axon → soma
- Motor protein = dynein
Wallerian Degeneration
- cutting axon from soma
- results in “strings on a bead” morphology
- axon is degenerating
What can go wrong in axoplasmic transport?
- mutations in motor protein:
- ATP binding site
- link regions
- microtubule binding site
- path physically disrupted
- lack of ATP
- Mutations/Disruptions of microtubules
- affects structure
- decreased expression of motor proteins
Oligodendrocytes
myelinate (insulate) axons in the CNS
