Formation of the Nervous System Flashcards
1
Q
How long is the pre-embryonic stage?
A
Conception to day 14
2
Q
What is the single cell that divdies into multiple cells forming a solid sphere of cells as it travels down the fallopian tube into uterine cavity?
A
Fertilized Ovum
3
Q
What is formed when there is a hollow of cells with innter cell mass becoming an embryo?
A
Cavity
4
Q
What does the outermost layer of sphere in pre-embryonic stage become?
A
Placenta
5
Q
What does the inner cell mask become during the pre-embryonic stage?
A
Embryonic disk
6
Q
What are the 2 layers of the embryonic disk?
A
- endoderm
- ectoderm
7
Q
What layer is formed between endoderm and ectocerm during pre-embryonic stage?
A
Mesoderm
8
Q
When does the first stage of development occur in gastrulation?
A
3rd gestational week
9
Q
What does the bilaminar disk embryonic disk become during gastrulation?
A
Trilaminar embryonic disk
10
Q
What are the 3 layers of the trilaminar embryonic disk?
A
- ectoderm
- mesoderm
- endoderm
11
Q
What layer of the trilaminar embroyonic disk is this?
develop sensory organs, epidermis and nervous system
A
Ectoderm
12
Q
What layer of the trilaminar embroyonic disk is this?
Develops dermis, muscles, skeleton and excretory and circulatory systems
A
Mesoderm
13
Q
What layer of the trilaminar embroyonic disk is this?
develops gut, liver, pancreas and respiratory system
A
Endoderm
14
Q
What is the process that results in formation of the neural tube
A
Neurulation
15
Q
When does neurulation occur?
A
4th gestational week
16
Q
What is neurulation induced by?
A
Notochord
17
Q
What is the longitudinal thickening of ectoderm; first formed on surface of embryo expanding from head to tail regions
A
Neural plate
18
Q
What are the edges of plate folded upward; creates the neural groove
A
Neural folds
19
Q
Where does the fushion of the neural tube occur?
A
occurs from middle out towards rostral and caudal ends
- cells on top of each fold dissociate
- cells with migrate away from tube and form various types of cells
- as tube closes is seperates from ectodermal surface
20
Q
What is the openings on the ends of neural tubes; will eventually close
A
Neuralpores
21
Q
When does the superior neuropore close?
A
27th day
22
Q
When does the inferior neuropore close?
A
3 days after the superior neuropore close (30th day)
23
Q
What layer of the neural tube is this?
Somas, cell bodies of neurons, and develop into gray matter
A
Inner layer
24
Q
What layer of the neural tube is this?
White matter containing processes of neurons comprising of axons of glia cells
A
Outer layer
25
What does the rostral end of the neural tube become?
Brain
26
# Which step of the formation of the neural tube is this?
- notochord includes ectoderm to differentiate and thicken into neural plate
- neural plate border seperates ectoderm from neural plate
Step 1: Neural plate formation
27
# Which step of the formation of the neural tube is this?
- neural plate bends dorsally forming the neural groove and folds
- neural palte border develops into neural crest
Step 2: Neural grooves and folds formation
28
# Which step of the formation of the neural tube is this?
- neural folds join at neural plate borders (neural crest) forming the neural tube
- neural crest disconnects from the epidermis
- neural crest cells differentiate to form PNS
Step 3: Neural tube formation
29
What is developed in the 3rd gestational week when columns divide into segmentated blocks of mesoderm
- appear in occipital region adjacent to neural groove
- added from rostral - to - caudal direction
Somite
30
# What layer of the somite is this?
Lateral part of somite, dermatome that develops into dermis of skin
Outermost layer
31
# What layer of the somite is this?
Postermedial region is the myotome
Myoblasts devlop into striated skeletal muscle
Middle layer
32
# What layer of the somite is this?
Anteromedial part is the scelrotome
gives rise to bone, vertebrae and skull
Innermost layer
33
# What cell is this?
Surrounds neural tube and notochord developing into the body of vertebrae forming vertebral arches (arches fuse at 8 weeks)
Sclerotome cells
34
What does the notochord become when it degenerate?
becomes nucleous pulpousus of IVD
35
# What development is this?
develops from mesoderm that surrounds brain and is derived from both somites and neuralcrest cells
Cranium development
36
# What section of the neural tube is this?
- motor plate
- axons here grow out of tube to innervate myotome region of somite
- forms myotome
- gray matter originates here develops into ventral horn in mature spinal cord
Ventral section
37
# What section of the neural tube is this?
- association with alar plate
- processes sensory information
- gray matter originates here & develops into dorsal horn
Dorsal section
38
What is a group of muslces derived from one somite and innervated by single spinal nerve root?
Myotome
39
How many segmental columns does the neural crest divide into?
2 columns
40
What projects laterally exiting through intervetebral foramina at same level
Spinal nerve roots
41
What extends to end of cortex
Spinal cord
42
Where does the spinal cord end at birth?
Around L3 - L4
43
Lumbrosacral spinal roots extend beyond the end of the spinal cord forming ____
cauda equina
44
What are the 3 primary vesicles formed during the 4th week?
- prosencephalon (forebrain)
- mesencephalon (midbrain)
- rhombencephalon (hindbrain)`
45
When do the 5 seconday vesicles develop?
5th week of gestation
46
Which 2 secondary vesicles form from prosencephalon?
- telencephalon
- diencephalon
47
Which 2 secondary vesicles form from rhomencephalon?
- melencephalon
- myelencephalon
48
# Which secondary vesicle is this?
becomes cerebral hemisphere; includes deep nuceli, white matter, cortex
telencephalon
49
# Which secondary vesicle is this?
becomes hypothalamus, thalamus and subthalamus
diencephalon
50
# Which secondary vesicle is this?
becomes pons and cerebellum
melencephalon
51
# Which secondary vesicle is this?
becomes medulla
myelencephalon
52
What is the series of bends developed on the straight neural tube
Flexures
53
# Which flexure is this?
- begins at spinal cord junction rhombencephalon
- makrs divsions between hindbrain and spinal cord at medulla's caudal margin
- disappears as posture changes and head becomes erect
cervical flexure
54
# Which flexure is this?
- develops in rhombencephalon and divides into 2 portions (melencephalon and myelencephalon)
Pontine flexure
55
# Which flexure is this?
- develops near junction of melencephalon and mesencephalaon
- delineates midbrain and forebrain structures from the caudal parts of the brain
Cephalic flexure
56
What is the ventricular system derived from?
Central canal in the neural tube
57
How many vesicles does the telencephalon contain?
2 lateral ventricles
58
Which ventricle does the cavity of the diencephalon become?
Third ventricle
59
What does the cavity of mesencephalon become?
Cerebral aquaduct
60
Which ventricle does the cavity of the rhombencephalon become?
4th ventricle
61
# What developmental stage of utero is this?
- conception day 4
- fertilization
- formation and implantation of the blastocyst
- formation of the bilaminar embryonic disk
Pre-embryonic
62
# What developmental stage of utero is this?
- day 15 - end of 8 weeks gestation
- formation of organs
- gastrulation
- neurulation
- formation of the notochord
- neural tube closure
- brain formation begins day 28
Embryonic
63
What is the formation of the trilaminar embryonic disk
gastrulation
64
What is the formation of the neural tube day 18 - 26
neurualation
65
# What developmental stage of utero is this?
- end of 8 weeks of gestation to birth
- further development of the nervous system
- myelination of axons begins in the fourth fetal month
Fetal
66
What follows dynamic lengthy sequence of integrated biologic events beginning 4 weeks after conception and continues into early childhood
Neuronal development
67
What is 2nd gestational month and is completed by birth
- mass production of neurons occurs via neural stem cells ventricular zone of the neural tube
cell proliferation
68
What is programmed cell death; genetically controlled to decrease number of neurons in adult levels
apoptosis
69
What is nuerons migrate from ventricular zone to their pre-deteremined destination
- once at final location neurons become mature with axons or go into apoptosis
Neuronal migration
70
What is enables by growth cones that facilitated growth toward certain targets and away from others
Axon development
71
What is increase in number and density of dendritic spines
dendritic arborization
72
What is formation of synpases between neurons that form around 23rd week of gestation
- peak production during 1st year of life
- formation and pruning of synapse can occur by things outside of nervous system
Synaptogenesis
73
What begins in early 3rd trimester with most rapid period during first 2 years of life; brain growth and maturation
Meylination
74
What is process by which structures, functions or forms of behavior become more speacilaized
differentitation
75
# Which synapotgenesis cortex is this?
starts at 2 months
Motor cortex
76
# Which synapotgenesis cortex is this?
starts at 3 months
Visual cortex
77
What is several axons may innerevate a single target cell occurs during nervous system development
Polyneuronal innervation
78
What starts to myelinate at 36 weeks gestation and is completed by end of 2nd year; myelination begins at proximal portion of axon
Corticospinal tract
79
Which axons myelinate first?
Shortest axons
80
# What is this an order of?
1. motor sensory nerve roots, special senses, brainstem
2. Upper extremity and trunk
3. lower extremity
4. posterior portion of frontal lobes, parietal lobes, occipital lobes
5. parietal-temporal association cortexes
6. pre-frontal cortex
Order of Myelination of Nervous System Structures
81
When do neurons first appear during brain growth?
second prenatal month
82
What is the time of rapid brain growth and development; starts at 3rd trimester and continues into 4th year; rapid brain growth occurs in first 2 yrs
Brain growth spurt
83
# Which period of neurologic development is this?
- occurs during development when axons are competing synaptic sites
- allows nervous system to optimize neural connections
- conditions of learning are optimal to produce permanent structural changes in nervous system
- experience controls competition between axons for synaptic site via impact on electrical activity, molecular mechanism and inhibitory actions
Critical period
84
# Which period of neurologic development is this?
- neural circuits are more responsive and plastic to influence of experience
- window of time where development is more easily achieved
Sensitive period
