Development Of Nervous System Flashcards

1
Q

What is the notochord?

A

Refers to a rod of cells

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2
Q

Where is the notochord located?

A

Runs in the midline of the embryo

In the mesoderm layer

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3
Q

During what process is the notochord formed?

A

Gastrulation

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4
Q

What is the function of the notochord?

A

Releases signalling molecules
Which diffuse upwards to the overlying ectoderm
Stimulate it to differentiate into neuroectoderm

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5
Q

What is the neural plate?

A

Refers to a thickening of neuroectoderm

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6
Q

What are neural folds?

A

Refers to the edges of the neural plate moving upwards

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7
Q

What is the neural groove?

A

Refers to the depression in the neural plate between the neural folds

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8
Q

What is neurulation?

A

Refers to the formation of the neural tube

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9
Q

How does neurulation occur?

A

Elevated edges of neural plate curl towards each other
Meet each other in the midline
Fuse together to form neural tube

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10
Q

What are neuropores?

A

Refers to openings at the ends of the neural tube

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11
Q

Where are the anterior and posterior neuropores located?

A

Anterior neuropore - cranial end of neural tube

Posterior neuropore - caudal end of neural tube

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12
Q

What happens to the neuropores during development?

A

Close up completely

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13
Q

What developmental abnormality causes neural tube defects?

A

Neuropores do not close up completely

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14
Q

What are two types of neural tube defects?

A

Spina bifida/cleft spine

Anencephaly

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15
Q

What developmental abnormality causes spina bifida?

A

Posterior neuropore doesn’t close up completely

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16
Q

Where does spina bifida occur in the spine?

A

Lumbo-sacral region

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17
Q

What is the structure of a low-severity spina bifida?

A

Spinal cord is deep

Cyst made up of meninges and CSF is near the surface

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18
Q

What is the structure of a high-severity spina bifida?

A

Cyst made up of meninges and CSF is deep

Spinal cord is near the surface

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19
Q

What are the signs of spina bifida? Why do they occur?

A

Neurological deficits, due to problems with spinal cord
But no cognitive delay because no problem with brain

Hydrocephalus, due to meninges being abnormally tethered to spinal cord

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20
Q

What developmental abnormality causes anencephaly?

A

Anterior neuropore doesn’t close up completely

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21
Q

What is meant by anencephaly?

A

Cranial structures do not develop, including the brain

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22
Q

How are neural tube defects diagnosed?

A

Raised maternal serum alpha-fetoprotein

Ultrasound scan

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23
Q

Why is maternal serum alpha-fetoprotein raised with neural tube defects?

A

This is an embryonic protein that leaks out of the neural tube defect into amniotic fluid and then maternal circulation

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24
Q

How are neural tube defects prevented?

A

Folic acid pre-conceptually for 3 months and during the first trimester

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25
Q

What does the spinal cord develop from?

A

Most of caudal end of neural tube

26
Q

How does the cauda equina develop?

A

Initially vertebral column and spinal cord are same length
But then vertebral column grows faster
Spinal nerve roots elongate downwards to exit at their corresponding intervertebral foramina

27
Q

How many primary brain regions are there? What are they called?

A

Three

Forebrain, midbrain and hindbrain

28
Q

When do the primary brain regions develop?

A

As the neural folds form

29
Q

When do the primary brain vesicles develop?

A

As the neural tube forms

30
Q

How many secondary brain vesicles are there?

A

Five

31
Q

What are flexures?

A

Folds in the cranial neural tube

32
Q

Why do flexures form?

A

Cranial neural tube grows and runs out of space

So it folds to maximise its use of space

33
Q

How many flexures are there? What are they called?

A

Two

Cervical and cephalic

34
Q

Where along the cranial neural tube is the cervical flexure?

A

Between the spinal cord and hindbrain

35
Q

Where along the cranial neural tube is the cephalic flexure?

A

In the midbrain

36
Q

What does the ventricular system develop from?

A

The lumen of the neural tube

38
Q

What is hydrocephalus?

A

Accumulation of CSF in the ventricular system

39
Q

How is the neural tube organised?

A

Deep layer
Intermediate layer
Marginal layer

Dorsal end
Ventral end

40
Q

What is the deep layer of the neural tube made up of?

A

Neuroepithelial cells

41
Q

What is the function of the neuroepithelial cells of the deep layer of the neural tube?

A

Line the ventricular system

Produce CSF

42
Q

What is the intermediate layer of the neural tube made up of?

A

Neuroblast cell bodies

43
Q

What is the marginal layer of the neural tube made up of?

A

Processes of neuroblasts

44
Q

What are the dorsal and ventral ends of the neural tube made up of?

A

Dorsal end is made up of roof plate

Ventral end is made up of floor plate

45
Q

What is the function of the roof and floor plates of the neural tube?

A

Regulate dorsal and ventral patterning of the neural tube

Divide intermediate layer into alar plate and basal plate

46
Q

Where are neural crest cells located in the embryo?

A

Lateral border of neuroectoderm

47
Q

What happens to neural crest cells during development?

A

Become displaced and enter the mesoderm
Undergo epithelial to mesenchymal transition
Migrate to other regions of embryo

48
Q

What do neural crest cells develop into?

A

Wide range of structures
E.g. cranial nerve ganglia, dorsal root ganglia, autonomic ganglia, Schwann cells, connective tissue of face and skull, septum of heart, melanocytes

49
Q

What developmental abnormalities can occur with neural crest cells?

A

Problems with migration

Problems with morphogenesis

50
Q

What is an example of a condition with abnormal development of neural crest cells?

A

DiGeorge syndrome

51
Q

What abnormalities are present in people with DiGeorge syndrome due to abnormalities in neural crest cell development?

A

Congenital aphasia of thymus gland
Aplastic parathyroid glands
Cardiac defects

52
Q

What body system is the first to begin development?

A

Nervous system

53
Q

Which body system is the last to complete development?

A

Nervous system

54
Q

When does the nervous system complete development?

A

End of first year after birth

55
Q

Which body system is the most susceptible to damage during pregnancy? Why?

A

Nervous system

Because it is developing throughout the entire pregnancy

56
Q

What is the relative position of the alar plate?

A

Dorsal

57
Q

What is the function of the alar plate?

A

Sensory functions

58
Q

What is the relative position of the basal plate?

A

Ventral

59
Q

What are the functions of the basal plate?

A

Motor functions

60
Q

What causes hydrocephalus?

A

Blockage of ventricular system

E.g. stenosis, infection, tumour

61
Q

How is hydrocephalus treated?

A

Use of shunt

62
Q

How does the brain develop?

A

Primary brain regions develop
Then primary brain vesicles
Then secondary brain vesicles

63
Q

How does the ventricular system develop?

A

When the five secondary brain vesicles form, there is an empty space in each one
These empty spaces develop into the ventricles