Zaidi development round 2 Flashcards
Describe the phases of neural development
phase 1- different cell types develop independently in separate locations according to local program and are unconnected
phase 2- axons and dendrites grow outward and provide a basic orderly network of connections including synapse formation
phase 3- connections are adjusted and refined throughtou the persons lifetime via electric signals
Describe the origin of the nervous system
neurons and glial cells are from the ectoderm
CNS comes from neural tube and PNS from the neural crest
Describe the formation of the neural tube including the importance of delta notch signaling
neural tube starts from a single layer of epithelial cells on the neural groove on the dorsal side of the embryo; neural folds form and deepen forming the neural tube and neural canal (center of the tube)
delta notch signaling allows differentiation into neurons; morphogens help to allow expression of different gene regulatory proteins
Describe the neural crest
at the dorsal end of the neural tube
migrate shortly after the closure of the neural tube; generate the PNS, epinephrine cells of the adrenal gland, and skeletal and connective tissues
depend on where they migrate to and settle
How does a neuron move?
There is a growth cone that is a spiky enlargement at the tip of an axe that is able to crawl around to surrounding tissue
it is able to steer and guide the cell to where it needs to go via cytoskeletal machinery, filopodia, lamelopodia, and monomeric GTPases rho and Rac control actin filaments
Describe in detail how growth cones are able to move
- cytoskeletal machinery
- lamelopodia and filopodia
- monomeric GTPAses Rho and Sac which control the assembly/dissamebly of actin filaments
- Using cues
a. extracellular matrix environment (receptors on membrane via contact guidance)
b. chemotactic factors (released by the neighboring cells, are attractive or repulsive)
Describe the movement of growth cones in the extracellular matrix
- use receptors that are present in the membrane
- contact guidance from previous cells
two important classes (IG and cadherin) either will favor outgrowth or ingrowth
What does laminin favor in regards to axonal growth?
Outgrowth
What does chondroitin sulfate proteoglycan favor in regards to growth?
It inhibits
which portions of spinal neurons develop into sensory or motor neurons respectively?
dorsal- sensory
ventral-motor
intermediate-inter-neurons
Describe commissural neuron guidance
- depends on the secretion of netrin (chemotactic factor)
- binding of entrain causes the opening of TRPC which allows extracellular calcium in
- activates growth cone movement via filopodia extension
- midline secretes slit which repels growth cones so it does enter
- other growth cones repel each other with semaphoring which cause them to go on a narrow track
Describe the nerve growth factor
First one identified was NGF (nerve growth factor)
is a neurotrophic
receptor is a tyrosine kinase (trek) and it promotes the survival of neurons
Describe the short and long term effects on NGF
short- effect on growth cone an neuritis extension; local rapid effect
long- effect on cell survival; mediated by receptor
Describe synaptic remodeling
dependent on 2 rules
- axons from cells in different regions of retina compete for tectal neurons
- axons from neighboring sites are excited at the same time and cooperate/collaborate to retain and strengthen synapses
Describe activity dependent synaptic remodeling
depends on electrical activity and synaptic signaling
