Nervous System Flashcards
(72 cards)
1
Q
The nervous system consists of 3 parts
A
- Central Nervous system (CNS) which includes the brain and spinal cord
- The peripheral nervous system (PNS), which includes neruons outside the CNS and, cranial and spinal nerves that connect the brain and spinal cord with peripheral structures
- Automatic nervous system (ANS), which has parts in both the CNS and PNS and consists of neurones that innervate smooth muscle, cardiac muscle, glandular epithelium, or combinations of these tissues
2
Q
The neural tube differentiators into the ________, consisting of ________
A
CNS
brain and spinal cord
3
Q
Neural crest gives rise to
A
Cells that form most of the PNS and ANS, consisting of cranial, spinal, and autonomic ganglia, and many other structures
4
Q
The nervous system develops from the
A
Neural plate
5
Q
The notochord and practical mesenchyme induce _____ to differentiate into the ______
A
Overlying ectoderm
Neural plate
6
Q
Signalling molecules used to induce neural tube
A
TGF-Beta family
Shh
BMP
7
Q
Molecular signals for brain development are initiated at the neural plate stage:
What established sensory and motor regions
A
BMPS establish sensory regions
Shh established motor regions
8
Q
BMPS AND SHH are released in ______ gradients
A
Opposite
Ventral has more shh
Dorsal has more BMP
9
Q
Shh is secreted by the _____ and the ______ in the neural tube
BMP’s are secreted by the ______ of the neural tube
A
Notochord
Floorplate
Roofplate
10
Q
Neurulation
A
Formation of the neural plate and neural tube begins in 3rd week
11
Q
Neural tube formation begins in the ___ week and is complete by the end of the ____ week
A
3rd
4th
12
Q
The cranial opening of the neural tube _______ closes on approximately the ___ day while the ______ closes on the ____ day
A
Anterior neural pore or rostral
25th
Caudal neuropore or posterior neural pore
27th
13
Q
Neural tube closure established the
A
CNS
14
Q
The walls of the neural tube thicken to form the ________
A
Brain and spinal cord
15
Q
Neural canal forms
A
- ventricular system if the brain (anterior)
- central canal of the spinal cord (posterior)
16
Q
Cells of the wall of the neural tube (neuroepithelial) proliferate and the _______ decreases
A
Lumen
17
Q
Neuroepithelial cells produce 3 types of cells….
A
Histogenesis of cells in the CNS
- Neuroblast (form neurons)
- apolar
- bipolar
- unipolar - Glioblast (spongioblast) which become
Macroglia: Atroblast and Oligodendroblast - Ependyma (cells remaining next to neural canal)
Happens in this order
18
Q
Microglial cells are derived from ________ and serve as
A
Mesenchymal cells that invade the developing nervous system with blood vessels
Immune response cells
19
Q
Walls of neural tube differentiate into 3 layers:
A
- inner ventricular layer
- intermediate layer
- outer marginal layer
20
Q
Where in the neural tube wall are the 3 types of neuroepithelial cells
A
- ependymal cells remain in ventricular layer
- neuroblasts and glioblasts complete differentiation in the intermediate layer
- marginal zone is outer parts of neurons and also glial cells
21
Q
Development of spinal cord
A
- neural tube caudal to the 4th pair of somites develops into the spinal cord
- lateral walls of the neural tube thicken, gradually reducing the size of the neural canal until only a minute central canal of the spinal cord is present at 9-10 weeks.
22
Q
Spinal cord develops from the _____ parts of the _____
A
Caudal
Neural tube
23
Q
Roof and floor of neural tube are
A
Thin plates
24
Q
Side walls of neural tube thicken and the ______ separate the side walls into
A
Sulcus separates
Dorsal (alar) plates
Ventral (basal) plates
25
Alar plates become the __________
Dorsal horns of gray matter
- neuron cell bodies are in the intermediate layer. The marginal layer becomes the white matter
- have afferent/ sensory function
26
2/3 of neural tube becomes ____
| 1/3 becomes _____
Brain
Spinal cord
27
Neuron function different based on dorsal/ ventral aspect
-afferent/sensory (grow into alar plates) dorsal=BMP
-efferent/ motor (grow out of basal plate)
Ventral=shh
28
The intermediate layer of the neural tube is also called the
Mantle
29
Unipolar neurons in the spinal ganglia (dorsal root ganglia) are derived from
Neural crest cells
30
The axons of cells in the spinal ganglia are first _____, but the two processes soon untie in a _______ fashion
Bipolar
T-shaped
31
Neural crest cells give rise to
Dorsal root ganglia (cell bodies of sensory neurons)
32
Peripheral processes are in _____
Central processes enter spinal cord as ______
Spinal nerves
Dorsal root of spinal nerve and enter dorsal horn of grey matter
33
Basal plates becomes the _______ and _______
Lateral and ventral horns of grey matter
34
Basal plates have an ____ function
Efferent
35
Axons of nerurons in ventral horn grow out of _______ and form ______
Spinal cord
Ventral roots of spinal nerves
36
Spinal nerve divides into dorsal and ventral _____
Primary rami
- dorsal primary rant Innervate the limbs, vertebral joints and the skin of the back
- ventral primary ramy innervate the limbs and ventral body wall
37
Development of the spinal Meninges
- mesenchyme surrounding the neural tube condensed to form a membrane called the primordial meninx or meninges
- external layer of this membrane thickens to form the dura mater
- internal layer (pia-arachnoid), composed of pia mater and arachnoid mater (leptomeninges), is derived from neural crest cells
- cerebrospinal fluid begins to form during the 5th week
38
When does CSF begin to form
5 the week
39
Pia-arachnoid (leptomeninges) is derived from
Neural crest cells
40
Positional changes of the spinal cord
Because the vertebral column grows more rapidly than the spinal cord, the position of the spinal cord within the vertebral column changes
- spinal cord comes to lie at progressively higher levels without the vertebral column
- end at L1 in adult
41
Myelination of Nerve fibres
- Begins during late fetal period and continues during first year after birth
- in PNS, myelin is formed by Schwann cells (from neural crest)
- in CNS, myelin is formed by Oligodendrocytes
- tracks become functional when myelinated
42
How does Myelin sheath speed up action potential
- insulation helps impulses to hop instead of moving in a straight line which is quicker.
- nodes of ravier
43
Development of the brain
- cranial part of the neural tube becomes the brain
- neural tube dilates in the 4th week giving rise to 3 primary brain vesicles
- forebrain (prosencephalon)
- midbrain (mesencephalon)
- hindbrain (rhombencephalon)
44
What creates the dilations in developing brain
-walls of neural tube expand rapidly
45
During the ______ week, ___ secondary brain vesicles are formed as the ______ and ______ divide
5
5
Forebrain
Hindbrain
46
5 secondary vesicles
Forebrain:
- telencephalon
- diencephalon
Midbrain
Hindbrain:
- metencephalon
- myelencephalon
47
5 secondary vesicles and the adult derived structures
```
Medulla-mylencephalon
Pons and cerebellum-metencephalon
Midbrain-mesocephalon
Thalami-Diecephalon
Cerebrum-Telencephalon
```
48
Adults brain cavities and their derivatives
Lateral ventricles from Telencephalon
Third ventricle from Diencephalon
Aqueduct from midbrain
Upper part of fourth ventricle from Metencephalon
Lower part of fourth ventricle from myelenchephalon
49
The _________ demarcates the hindbrain from the spinal cord
Cervical flexure
50
The ______ divides the hindbrain into caudal - myelencephalon and rostral - metencephalon
Pontine flexure
51
The myelencephalon becomes the ______ and the metencephalon becomes the _______
Medulla
Pons and cerebellum
52
Regions of Medulla
Medulla has 2 regions
- caudal closed region
- rostral open region
53
Unlike those of the spinal cord, neuroblasts from the alar plates in the myelenchephalon migrate into the __________ and form ________
Marginal zone
Isolated areas of gray matter
- the gracile nuclei medically
- cube ate nuclei laterally
54
Neuroblasts in the closed region of the medulla
Open part of medulla
The closed region of the medulla is similar in structure to the spinal cord.
-neuroblasts of alar plates form discrete nuclei (gracile nuclei and cube are nuclei)
Open part is wide and flat
- motor nuclei lie medial to the sensory nuclei
- neural canal becomes part of the 4th ventricle
55
Neuroblasts in the alar plates of the medulla form neurons that are arranged in ______ Columns on each side. From medial to lateral they are:
4
General visceral afferent: recurve impulses from the viscera
special visceral afferent: receiving taste fibres
General somatic afferent: receiving impulses from the surface of the head
Special somatic afferent: receive impulses from the ear
56
Neuroblasts in the basal plates of the medulla, organize into ____ cell volume on each side. From medial to lateral, they are:
3
General somatic efferent: neurons of the hypoglossal nerve
Special visceral efferent: neurons innervating muscles derived from the pharyngeal arches
General visceral efferent: neurons of the vagus and glossopharyngeal nerves
57
The thin ependymal roof of the 4th ventricle is covered externally by
Pia mater from mesenchyme
58
The vascular membrane, together with the ependymal roof forms the _____ of the 4th ventricle
Tela choroidea
59
Because of the active proliferation of the pia mater, the _______invaginated the ________ where it differentiated into the _______
Tela choroidea
4th ventricle
Choroid plexus
60
What secretes ventricular fluid which becomes cerebral springlike fluid
Choroid plexuses
61
Development of the pons and cerebellum
- similar to open part of the medulla
- alar plates thicken to form the cerebellum
- neuroblasts migrate to the marginal zone forming the cerebellar cortex (grey matter)
- pons consists of large bundles of fibres connecting the cerebrum to the cerebellum and spinal cord
62
Midbrain develops from the
Mesencephalon
63
Development of the mesencephalon
- region undergoes the least amount of change and remains similar to the spinal cord
- neuoblasts of alar plates migrate and form 2 pairs of nuclei-superior and inferior colliculi involved in visual and auditory reflexes respectively
- neuron lasts of basal plates form several nuclei all with efferent functions
- ventral aspect has 2 bulges called cerebral peduncles which are fibre tracts coming from the cerebrum
- neural canal becomes the cerebral aqueduct
64
Prosencephalon develops into the
Diecephalon and telencephalon
| Can’t identify alar and basal plates
Demarked by sulcus limitans but can’t see it here
65
Diencephalon is ___ part of forebrain and gives rise to
Caudal
Epithalamus
Thalamus and
Hypothalamus
66
Neural canal becomes
Third ventricle
67
Pituitary gland develops from which tissues
- hypophysial diverticulum (roof of stomodeum)
| - neurohypophysial diverticulum (floor of diencephalon)
68
Telencephalon develops from the _____ most part of the ______ and becomes the ______
Cranial
Forebrain
Cerebrum
69
Cerebrum begins as a ______
2 bubble like outgrowths called cerebral vesicles which will become the left and right cerebral hemispheres
- as hemispheres expand the become c-shaped
- neural canal becomes the lateral ventricles
- cells of the intermediate layer migrate to the marg al layer giving rise to the cerebral cortex
70
Surface of the cerebrum is initially _____ but as hemispheres grow, become ______
Smooth
Convoluted (gyri and sulci)
71
Red nucleus not known if
Afferent or efferent
72
Pars nervosa is derived from
Neuropophysial diverticulum
