Ch. 4 - Development & Growth Of The Nervous System

Question 1

Nearly all new neurons are generated by when?

Answer 1

The end of fetal period and early neonatal period

Question 2

What are the first two organ systems to function?

Answer 2

1. Cardiovascular

2. Nervous

Question 3

When does the development in the form of new neural connections occur?

Answer 3

T/o the growth ages

Question 4

Can synaptic developments occur in old age?

Answer 4

Yes, with appropriate environmental stimuli

Question 5

Do neural cells regenerate?

Answer 5

No, they are specialized cells that cannot regenerate

Question 6

When does the total number of neurons start diminishing? Where?

Answer 6

Age 20, especially from the cerebral cortex.

Question 7

Total brain weight decreases:

___% from age 20 - 90

Answer 7

10%

Question 8

How much does nerve conduction velocity decrease?

Answer 8

10%

Question 9

What are the 3 layers of the embryonic disc?

Answer 9

1. Endoderm
2. Mesoderm
3. Ectoderm

Question 10

When does the neural plate form?

Answer 10

18 days after conception

Question 11

What does the neural plate form from?

Answer 11

Ectoderm

Question 12

The neural plate elongates and the lateral edges fold outward to form what?

Answer 12

Neural folds

Question 13

The rostral end of the neural plate enlarges and will later develop into what?

Answer 13

The brain

Question 14

The neural folds continue to grow and eventually meet in the midline beginning in the ________ region to form the ___________ which progresses cephalically and caudally

Answer 14

Cervical; neural tube

Question 15

The entire length of the neural tube is closed by when?

Answer 15

25 days

Question 16

What develops as a bilateral column of cells from the neural ectoderm?

Answer 16

Neural crest

Question 17

What 9 things do neural crest cells develop into?

Answer 17

1. Sensory ganglia
2. Autonomic ganglia
3. Enteric ganglia
4. Pia mater
5. Arachnoid mater
6. Sclera of the eye
7. Neurolemma
8. Adrenal medullary cells
9. Carotid body receptors

Question 18

What are the 4 basic zones (layers) of the neural tube from inside out?

Answer 18

1. Ventricular zone
2. Subventricular zone
3. Intermediate (mantle) zone
4. Marginal zone

Question 19

Neurons which migrate here will become the gray matter of CNS

Answer 19

Intermediate (mantle) zone

Question 20

Layer of small proliferative cells dividing as primitive neuro lasts which can migrate. Spongioblasts will become astrocytes and oliogodendroglia (myelin makers)

Answer 20

Subventricular zone

Question 21

The most central layer consists of dividing cells which then move out to the next two layers as precursor cells. The cells that remain in this layer are called ependymal cells

Answer 21

Ventricular zone

Question 22

Very few cells; distant axons migrate in /c macroglia to form the white matter

Answer 22

Marginal zone

Question 23

What 2 things are structural organization and function of cells determined by?

Answer 23

1. Intrinsic influences (mostly genetic)

2. Extrinsic influences (mostly environmental)

Question 24

The predictability of the form and connections of a neuron, and therefore its function; probably genetically determined (including destination of migration, structural characteristics of the cell, characteristic physiological properties of the cell)

Answer 24

Neural specificity

Question 25

Variation from the predictable pattern; probably the result of environmental factors as new synapses and interconnections are established

Answer 25

Neural plasticity

Question 26

What is a very important concept in rehab and in understanding primitive reflexes?

Answer 26

Neural plasticity

Question 27

Does the developing or the mature brain exhibit greater plasticity?

Answer 27

Developing

Question 28

What neural tube zone becomes the inner gray mater?

Answer 28

Intermediate zone

Question 29

What zone of the neural tube becomes the outer white matter

Answer 29

Marginal zone

Question 30

What are intermediate zone cells dorsal to the sulcus limit as called? Primarily motor or sensory?

Answer 30

Alar plate; sensory

Question 31

What are intermediate zone cells ventral to the sulcus limit as called? Primarily motor or sensory?

Answer 31

Basal plate; motor

Question 32

At what month does the spinal cord extend the entire length of the vertebral column?

Answer 32

3rd month; and the spinal roots 90 deg.

Question 33

True or False: after the spinal cord stops elongating, the vertebral column continues elongating

Answer 33

True

Question 34

At birth, the caudal end of the spinal cord is at ______, in a teen the spinal cord ends at _______

Answer 34

L3; L1-L2

Question 35

Each pair of nerves develops in association /c what?

Answer 35

Each pair of somites

Question 36

What are somites?

Answer 36

Musculoskeletal precursors

Question 37

What does the neural crest become at each level?

Answer 37

Paired sensory root ganglion of each spinal nerve

Question 38

What are the 3 dilations that arise from the rostral end of the neural tube by the 3rd week?

Answer 38

1. Prosencephalon 2. Mesencephalon 3. Rhombencephalon

Question 39

What does the forebrain originate from?

Answer 39

Prosencephalon

Question 40

What does the midbrain originate from?

Answer 40

Mesencephalon

Question 41

What does the hindbrain originate from?

Answer 41

Rhombencephalon

Question 42

By the ______, the 3 vesicles of brain development become 5

Answer 42

2nd month

Question 43

The prosencephalon becomes what 2 structures?

Answer 43

1. Telencephalon | 2. Diencephalon

Question 44

What does the telencephalon become?

Answer 44

Cortex & basal ganglia

Question 45

What does the diencephalon become?

Answer 45

Thalamus & hypothalamus

Question 46

The mesencephalon remains what?

Answer 46

The midbrain

Question 47

The rhombencephalon becomes what 2 structures?

Answer 47

1. Metencephalon | 2. Myelencephalon

Question 48

What does the metencephalon become?

Answer 48

The pons and cerebellum

Question 49

What does the myelencephalon become?

Answer 49

The medulla oblongata

Question 50

Develops as an acute bend anterior to the midbrain

Answer 50

Mesencephalic flexure

Question 51

Bend that forms on the posterior surface btw the meten- and myelen-cephalon

Answer 51

Pontine flexure

Question 52

Bend that develops on the anterior surface at the lower medulla

Answer 52

Cervical flexure

Question 53

At what stage in brain development is each brain region recognizable?

Answer 53

3 months

Question 54

When in brain development do the fissures begin /c the lateral cerebral fissure and the posterolateral sulcus of the cerebellum

Answer 54

4 months

Question 55

When in brain development are all the main gyri and sulci present?

Answer 55

7 months

Question 56

When in brain development are all lobes stubby and the insula is still seen on the surface?

Answer 56

9th month

Question 57

True or False: in the neonate, the insula is mostly covered by adjacent lobes, and superficial artery are straight

Answer 57

True

Question 58

When does the brain reach the relative size and proportions of the adult brain?

Answer 58

Age 2

Question 59

A newborn brain weighs _______; ______ by age 1

Answer 59

350g; 1000g

Question 60

What is used to measure brain growth in infants and children?

Answer 60

Head circumference

Question 61

Brain weight at puberty is how much of body weight?

Answer 61

2%

Question 62

Physiological/functional maturation of the nervous system depends upon progressive myelination, especially btw the ___________ and _________

Answer 62

3rd trimester; 2 years old

Question 63

True or False: 3/4 of congenital defects involve the nervous system

Answer 63

False; 1/2

Question 64

Abnormal development of the brain can be caused by what 4 things?

Answer 64

1. Genetic factors 2. Nutrition 3. Hormonal effects 4. Infections