Development of the nervous system Flashcards Preview

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Flashcards in Development of the nervous system Deck (50):
1

Which of the three germ layers does the nervous system arise from?

Ectoderm

2

Which structure that arises in the ectoderm forms the basis of the nervous system?

Neural plate

3

What happens to the neural plate once it starts to develop?

Starts to invaginate/fold > forms tube beneath ectoderm

4

What is the tube that forms beneath the ectoderm when the neural plate invaginates known as?

Neural groove

5

Where does the neural groove lie in relation to the notochord?

Neural groove is above notochord

6

What happens to the neural groove after it begins to form?

Deepens > edges come together and join in midline > creates a tubular structure that can break free from overlying ectoderm

7

What is the tubular structure formed from the folding of the neural groove called?

Neural tube

8

How is the neural tube formed?

Neural groove deepens > edges come together and join in midline > creates a tubular structure that can break free from overlying ectoderm

9

What is the first physical structure of the nervous system to form?

Neural tube

10

Describe the neural tube?

Simple tube Single cell thick

11

What does the neural tube go on to form?

Brain and spinal cord

12

What does the hole in the neural tube go on to form?

Ventricular system

13

What does the ventricular system arise from?

Hole in the neural tube

14

Describe the gradient that exists in the neural tube?

Rostral to caudal gradient

15

What is the consequence of the rostral to caudal gradient in the neural tube?

Development occurs faster at the head end and slower at the tail end Rostral end is older

16

Describe the order of neural tube closure?

Closure tends to start towards middle, and leave ends of neural tube open

Zippers shut up and down from that midpoint

 

 

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17

Gove examples of birth defects that arise as a result of failure of closure of the neural tube?

Spina bifida 

Anencephaly

18

Are the five 'zipping' processes in the closure of the neural tube dependent on each other?

No, largely indepedent

19

Briefly describe the segmentation process of the neural tube?

Rostral end of tube starts to well

3 distinct vesicles form

Further segmentation of these vesicles occurs 

20

Name the three vesicles initially formed by the segmetation of the neural tube? Which brain structure does each vesicle correspond to?

Prosencephalon (forebrain)

Mesencephalon (midbrain)

Rhombencephalon (hindbrain) 

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21

What does the prosencephalon further divide into?

Telencephalon and diencephalon 

22

What does the rombencephalon further didvide into?

Seven segments (r1-r7)

 

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23

Whathappens to the part of the neural tube that does not become segmented?

Intact neural tube goes on to form spinal cord

24

What do the pons and cerebellum arise from?

Metencephalon division of rhombencephalon 

25

What does the medulla arise from?

Myelencephalon division of rhombencephalon

26

What are the major derivatives of the telencephalon?

Cortex, basal ganglia, hippocampus

27

What are the major derivatives of the diencephalon?

Thalamus and hypothalamus

28

What does the caudal part of the neural tube go on to form?

Spinal cord

29

Describe the structure of the developing brain after neural tube segmentation has occured?

series of thin-walled bubbles

30

What is the neural crest?

cells tha lie between the neural groove and neural tube after the neural tube forms

31

What is the fate of the neural crest?

Cells migrate away to form a variety of structures:

- melanocytes

- PNS

- muscle, cartilage and bone of skul, jaw, face and pharynx

- dentine

32

Why are neural crest cells able to migrate so far throughout the developing embryo?

Cells are incredibly mobile 

33

What is the longest migration that the neural crest cells undergo?

Enteric migration 

Enter gut at oesophagus and migrate down to anal end 

34

What feature of neural crest cells to cancer cells regain when they metastasise?

Ability to migrate through body tissues

35

What is the epithelium of the neural tube called? Describe it?

Neuroepithelium

Sinle cell thick, pseudostratified columnar

36

How is the cortex developed?

Neuroepithelium adds layers (6)

Dividing cells at the base move to new position at the outer

37

Which defects can lead to cortex malformation?

Defects in genes that affect migration 

38

What is induction?

Developmental process in neurons that gives us the variety of neuronal types that we need for a functioning brain

 

Process for differentiating neurons

39

Describe the process of induction that occurs in the spinal cord?

Neural tube sits on top of notochord, which acts as prime organiser

 

Notochord sends out signals which affects closest part of neural tube

 

Floor plate formed > ANTERIOR/VENTRAL identified

 

Roof plate formed > POSTERIOR/DORSAL

40

Why is the floor plate so important in spinal cord development?

Cells start releasing signals > forms diffusion gradient up and across rest of spinal cord > cells immediately next to them know that they are in ventral part of spinal cord > form ventral horn motor neurons 

41

What is the consequence of the absence of the floor plate?

No motor neurons develop

42

How are interneurons induced in the spinal cord?

Appear just dorsal to motor neurons due to inductive events 

43

How do axons grow?

Grow out to meet target cell

Towed into position by growth cone 

44

What are pioneer axons?

First axons to appear

Form a scaffold which later axons can build upon/follow

45

What are growth cones?

Structures which guide axon growth and tow them into position

46

Describe the structure of growth cones?

Dynamic structure of cytoskleleton 

47

What guides axon navigation?

Growth steers towards target due to diffusible and membrane bound signals 

48

Is the development of the nervous system complete at birth?

No; only a crude nervous system

49

What is the critical period in the development of the nervous system?

Time after birth in which refinement of the crude NS occurs 

50

What is the effect of temporary eye closure during the critical period on the visual cortex?

Cortex changes

Open eye has greatly increased representation , deprived eye has greatly reduced representation