axonal growth Flashcards
what is the first step in neuronal identity & formation of connections
polarization
where are growth cones located?
axonal tips
what is the function of the growth cones?
determines direction of growth, guides extension of axon, key decision-making structure in axon pathfinding
what structure is this statement describing?
“fan shaped sheet at tip of axon; contains actin filaments & microtubules”
lamellapodium
what structure is this statement describing?
“fine processes extending out from lamellapodium; contain actin filaments; form & disappear rapidly”
filopodia
what structure is primarily responsible for axon elongation? for dictating direction?
microtubules for elongation
F-actin for dictating direction
what are examples of non diffusible molecules?
collagen fibronectin laminin CAMs semaphorins ephrins
are cadherins diffusible or non diffusible? attractive or repulsive?
non diffusible
attractive
are semaphorins diffusible or non diffusible? attractive or repulsive?
non diffusible
repellent
are ephrins diffusible or non diffusible? attractive or repulsive?
non diffusible
repellent
are netrins diffusible or non diffusible? attractive or repulsive?
diffusible
attractive or repellent
are slits diffusible or non diffusible? attractive or repulsive?
diffusible
repellent
if the netrins are part of the DCC are they attractive or repellent?
attractive
if netrins are repellent, what family are they part of?
UNC5
what is the function of neurexin?
helps localize cytoskeletal elements, synaptic vesicles, active zone proteins and voltage gated Ca++ channels to the presynaptic membrane
what is the function of neuroligin?
recruits neurotrnasmitter receptors and other post synaptic proteins
what do “tropic interactions” ensure?
that each target cell is innervated by the right number of axons and each axon innervates the right number of cells
how are axonal branching patterns refined?
via competition and synapse elimination
what is the function of neurotrophins?
survival of a subset of neurons
form and maintain appropriate numbers of connections
elaboration of axonal and dendritic branches to support connections
what are the two neurotrophin receptors?
Trk and p75
what 3 things do neurotrophic interactions depend on?
- neurotrophins secreted by target cells
- neurotrophin receptors on neuron
- intracellular signaling cascades present in neuron
what 3 things do neurotrophic interactions determine?
- numbers of neurons
- shape of neurons (degree of aborization)
- patterns of neuronal connections (number of synapses)
are the non diffusible molecules in the EMC of the CNS largely attractive or repulsive? for the PNS?
in the CNS largely repulsive
in the PNS largely attractive
