development of the nervous system Flashcards
what makes up the CNS and PNS
neural tube and neural crest
what does notochord secretes
sonic hedgehog protein
What does roof plate secretes
bone morphogenetic proteins (BMP)
function of retinoic acid, Wnt and fibroblast growth factor
activate TF that activate expression of other genes which in turn affect the morphology of developing cells
primary and secondary vesicles
3 - prosencephalon, mesencephalon and rhombencephalon. 5 - telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon
what makes up the mantle layer
alar plate and basal plate
name the three steps in neurogenesis
cell proliferation, cell migration and cell differentiation
how do cell migrates
immature neurons follow raidal path from VZ towards surface and form cortical plate. Reelin secreted in cortical plate provides stop signal for neuroblast to detach from radial glial process
what determines how branched the neuronal typr
what signalling molecule it has been exposed to and presence of local signals
what is the process of cell differentiation
begins with neurites and soon becomes axon and the other is dendrites
what is growth cone
growth tip of neurite, which interacts with surrounding and directs the growth towards final target
how does growth of neurite occurs
filopodium takes hold of surface it is growing towards and pull the advancing growth cone forward
What does integrins on filopodia does
binds to ECM proteins (laminin and fibronectin), connects to cytoskeleton pulling axon towards the anchoring point
name a chemoattractant in axon guidance
netrin, neurotrophin, attracts axons which possess the netrin receptor
name a chemorepellent
slit
describe formation of neuromuscular junction (between motor neuron and target muscle )
growing neuron terminal secretes agrin into basal lamina. agrin interacts with agrin receptors leads to clustering of acetylcholine receptors on postsypnatic membrane via action of rapsyn
describe synapse formation in CNS
- A dendritic filopodium randomly contacts an axon
- Contacts lead to the recruitment of synaptic vesicles and active zone proteins to the pre-synaptic membrane
- Neurotransmitter receptors accumulate post-synaptically
Which cells is essential for formation and stabilisation of new synapse
astrocytes, they supply cholesterol
What happen when there is excess synapse?
- Go through Synaptic pruning process
- Start during first year after birth and continuing well after puberty
- Selection depends on activity, successful synapses used with a certain ‘sensitive period are reinforced and stabilised, rest is eliminated
What may disrupt neuronal development
genetic factors - down syndrome, environmental abnormalities, defects in neuronal migration - lissencephaly (smooth brain), failure of neural tube to close - spina bifida, anenecephaly
