Development Of Multicellular Org II

Question 1

Growth Cones travel towards target cells along what?

Answer 1

Predictable routes

Question 2

Short term effects of NGF

Answer 2

• Effect on growth cone and Neurite extension
• Local, direct, and rapid
• INDEPENDENT of communication with the cell body

Question 3

How many neurons in the brain?

Answer 3

10E11

Question 4

Phase 2 of Neural Development

Answer 4

• Axons and Dendrites grow out along specific routes

- Setting up a Provisional but ORDERLY Network of connections b/w various parts of the system

Question 5

Formation of the neural tube

Answer 5

• Starts w/ a Neural GROOVE on the Dorsal side of the Embryo
• Gradually deepens as Neural FOLDS become elevated
• Ultimately the folds meet and coalesce in the middle
• Closes to form a tube

Question 6

Ex of Chemotactic Factors

Answer 6

1. Netrin (attractant)
2. Slit (repellent)
3. Semaphorin (repellent pushing Neuron to Brain)

Question 7

Neural crest generate what cell types?

Answer 7

1. Neurons and Glial cells of the PNS
2. Epinephrine producing cells of adrenal gland
3. Many Skeletal and CT of the HEAD

Question 8

T/F: Axons and Dendrites are NOT distinguishable at first?

Answer 8

True

Question 9

Characteristics of Chemotactic Factors

Answer 9

• Secreted by cells
• Acts as guidance factors at strategic points along path
• May be Attractive or Repulsive

Question 10

Neurulation

Answer 10

Closure of the Neural Tube

Question 11

Roof Plate of the Neural Tube secretes what?

Answer 11

BMP and Wnt

Question 12

What does Signal proteins secreted fro the Ventral and Dorsal side of the Neural Tube do?

Answer 12

• Act as opposing Morphogens

- Causing neurons at diff D/V positions to express Different Regulatory proteins

Question 13

PNS origin

Answer 13

Derived from the Neural CREST

• Nerves, sensory neurons

Question 14

What triggers the lasting change in synaptic strength?

Answer 14

Entry of Ca2+ through the Glutamate receptor

Question 15

What regulates which growth cones synapse and where?

Answer 15

Signal from target tissue

Question 16

The center of the Neural Tube is called what?

Answer 16

Neural CANAL

Question 17

Typical axon length range

Answer 17

Less than 1mm

To

More than 1m

Question 18

What Matrix molec favors growth? Which one inhibits it?

Answer 18

1. Laminin

2. Chondroitin Sulfate PTG

Question 19

What forms a axon in Neuronal migration?

Answer 19

When a growth CONE starts migrating Fast

• Develops Axon-Specific Proteins

Question 20

How many connections does one Neuron make?

Answer 20

About 1000

Question 21

Neural crest Migration

Answer 21

Migrate extensively during or shortly after neurulation

Question 22

The Fate of the Neural Crest cells depend on what?

Answer 22

Where the MIGRATE to

Question 23

What rules are Synaptic Remodeling dependent on?

Answer 23

1. Axons from cells in DIFFERENT regions of Retina COMPETE for tectal neurons
2. Axons from NEIGHBORING sites which are excited at SAME time to strengthen synapses

Question 24

Role of the Tectum

Answer 24

Responsible for Visual and Auditory Reflexes

Question 25

Floor Plate of the Neural Tube secretes what?

Answer 25

SHH

Question 26

Where do Neural Crest cells originate?

Answer 26

From the DORSAL End of the Neural Tube

Question 27

Long term effects of NGF

Answer 27

- Effect on cell Survival - Mediated by its receptor - Uptake into cells via Endocytosis and stimulation do downstream signaling pathways

Question 28

CNS origin

Answer 28

Derived from the Neural TUBE - Brain, SC, Retina

Question 29

Activity Dependent synaptic remodeling is dependent on what?

Answer 29

ELECTRICAL activity And Synaptic signaling

Question 30

Why do 50% of Neurons die after they reach target cell?

Answer 30

- Made in excess - Target cell produces limited amount of specific Neurotropic factors needed for survival - Those that do not get enough die by PCD

Question 31

Phase 1 of Neural Development

Answer 31

- Diff cell types (Neurons, glia) develop INDEPENDENTLY - At widely separate locations in embryo according to local program - UNCONNECTED

Question 32

Neurons are produced in association with what?

Answer 32

Glial Cells

Question 33

In the Neural Tube, what controls Lateral Inhibition and Positive Feedback?

Answer 33

Delta Notch

Question 34

EMC mediated by what?

Answer 34

Homophilic Cell adhesion molecules 1. IG Superfamily 2. Cadherin Family

Question 35

Growth cone behavior

Answer 35

- Dictated by its cytoskeletal Machinery | - Throw out Filopodia and Lamelopodia

Question 36

What controls the movement of Growth Cones?

Answer 36

- Monomeric GTPases Rho and Rac | - They control the assembly/disassembly of ACTIN Filaments

Question 37

Characteristics of Nerve Growth Factor.

Answer 37

- Belongs to fam of Neurotrophins - NGF receptor is Tyrosine Kinase A - Promotes the SURVIVAL of specific sensory neurons and sympathetic neurons

Question 38

The two ways that Growth Cones find their way around.

Answer 38

1. ECM Environment - Sensed by RECEPTORS present on membrane 2. Chemotactic Factors - Released by Neighboring cells - Attractive or repulsive

Question 39

Growth Cone

Answer 39

- Spiky enlargement on the tip of the Axon/Dendrite | - Crawls through surrounding tissue

Question 40

Phase 3 of Neural Development

Answer 40

- Continues in ADULT life - Connections are adjusted and refined through interactions - Distant regions are connected via electric signal

Question 41

Contact Guidance

Answer 41

Growth cones follow a path taken by other cells