development of the nervous system

Question 1

what makes up the CNS and PNS

Answer 1

neural tube and neural crest

Question 2

what does notochord secretes

Answer 2

sonic hedgehog protein

Question 3

What does roof plate secretes

Answer 3

bone morphogenetic proteins (BMP)

Question 4

function of retinoic acid, Wnt and fibroblast growth factor

Answer 4

activate TF that activate expression of other genes which in turn affect the morphology of developing cells

Question 5

primary and secondary vesicles

Answer 5

3 - prosencephalon, mesencephalon and rhombencephalon. 5 - telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon

Question 6

what makes up the mantle layer

Answer 6

alar plate and basal plate

Question 7

name the three steps in neurogenesis

Answer 7

cell proliferation, cell migration and cell differentiation

Question 8

how do cell migrates

Answer 8

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

Question 9

what determines how branched the neuronal typr

Answer 9

what signalling molecule it has been exposed to and presence of local signals

Question 10

what is the process of cell differentiation

Answer 10

begins with neurites and soon becomes axon and the other is dendrites

Question 11

what is growth cone

Answer 11

growth tip of neurite, which interacts with surrounding and directs the growth towards final target

Question 12

how does growth of neurite occurs

Answer 12

filopodium takes hold of surface it is growing towards and pull the advancing growth cone forward

Question 13

What does integrins on filopodia does

Answer 13

binds to ECM proteins (laminin and fibronectin), connects to cytoskeleton pulling axon towards the anchoring point

Question 14

name a chemoattractant in axon guidance

Answer 14

netrin, neurotrophin, attracts axons which possess the netrin receptor

Question 15

name a chemorepellent

Answer 15

slit

Question 16

describe formation of neuromuscular junction (between motor neuron and target muscle )

Answer 16

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

Question 17

describe synapse formation in CNS

Answer 17

1. A dendritic filopodium randomly contacts an axon
   
   2. Contacts lead to the recruitment of synaptic vesicles and active zone proteins to the pre-synaptic membrane
   3. Neurotransmitter receptors accumulate post-synaptically

Question 18

Which cells is essential for formation and stabilisation of new synapse

Answer 18

astrocytes, they supply cholesterol

Question 19

What happen when there is excess synapse?

Answer 19

• 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

Question 20

What may disrupt neuronal development

Answer 20

genetic factors - down syndrome, environmental abnormalities, defects in neuronal migration - lissencephaly (smooth brain), failure of neural tube to close - spina bifida, anenecephaly