001 Nervous System Development Flashcards

1
Q

• describe the general function of the nervous system

A

o Consists of the structures in the body that are composed of neural tissue
o Functions
 Correlate the adjustments and reactions of an organism to internal and environmental conditions

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2
Q

• list and describe the anatomic parts of the nervous system

A
	Central Nervous System (CNS)
•	Consists of 
o	the brain (encephalon)
o	Spinal cord (spinal medulla)
•	Two regions of CNS
o	Gray matter (darker to the eye)
	Has more nerve cell bodies
	Has fewer myelinated processes
	Neuropil – the mass of fibers in the gray matter
o	White matter
	Has more myelinated processes
	NO nerve cell bodies
	Peripheral Nervous System (PNS)
•	Consists of
o	Nerves (bundles of nerve fibers)
o	Ganglia (collections of nerve cell bodies in the PNS
o	Specialized nerve endings (like rods and cones of the retina)
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3
Q

Functional Parts of the nervous system

A
	Autonomic Nervous System (ANS)
•	Involuntary control of:
o	Cardiac muscle
o	Smooth muscle
o	Glands
•	Divided into two parts
o	Sympathetic – energy using
o	Parasympathetic – energy sparing
	Somatic Nervous System
•	Voluntary control of all other structures of the body
•	Sensory information from all structures of body
•	Includes:
o	Skeletal muscles, bones, joints, skin, ears and eyes
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4
Q

Describe nervous tissue

A
	Highly vascularized
	Neurons (AKA Nerve cells)
•	Functional units of the nervous system
o	Receive stimuli
o	Conduct impulses (action potentials
•	Made of
o	Cell bodies (AKA soma or perikaryon)
o	Processes
	Axons
	Dendrites
	Nerve fibers – long cytoplasmic extensions of a nerve cell (i.e. axons)
	Nucleus – collection of nerve cell bodies in the CNS
	Supporting cells
•	Two types
o	Neuroglia – supporting cells in CNS
	Oligodendrocytes
	Astrocytes
	Microglia
	Ependymal cells
o	Unnamed group of supporting cells in the PNS
	Schwann cells
	Satellite cells
•	Functions
o	Physically protect neurons because there is no CT in the CNS by providing physical strength
o	Some help provide electrochemical insulation to the neurons to speed up the velocity of the nerve impulses
o	Help regulate the metabolic exchange of the neurons to maintain the survival of the neurons
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5
Q

• compare and contrast neural nucleus and ganglion

A

o Neural nucleus
 Collection of cell bodies within the CNS
o Ganglion
 Collection of cell bodies within the PNS

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6
Q

What is and What embryonic week does blastocyst formation occur?

A

 hollow ball of cells that are pretty much identical

 Week 1

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7
Q

What is and What embryonic week does bilaminar disc formation occur?

A

 End of week 2
 Flattened disc of cells with two distinct populations
• Epiblast – cells in the bilaminar disc that actually form the embryo
• Hypoblast – cells that form the support structures of the embryo (placenta)

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8
Q

What is and What embryonic week does trilaminar disc formation occur?

A

 Week 3
 Has three distinct cell populations (germ layers developed from the epiblast)
 Basis for all adult tissues of the body

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9
Q

What is and What embryonic week does neurulation occur?

A

 Week 3

 The process of the formation of the neural tube which becomes the CNS

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10
Q

What is the notochord

A

 Rod of cells that forms directly from the epiblast cells
 Defines the primordial axis of the embryo (determines head end from tail end of the embryo)
 Basis for the axial skeletal development (vertebral column)
 Induces the development of the nervous system (tells the neuroectoderm to form)

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11
Q

• list the three (3) germ layers of the trilaminar disc

A

o Ectoderm
 Surface ectoderm
• Eventually forms the epidermis of the skin
 Neuroectoderm
• Forms the nervous system
o Mesoderm
 Forms most of the connective tissues and muscles of the body
 Forms the cardiovascular system, including blood
 Forms the urinary system
o Endoderm (AKA entoderm)
 Forms the lining of the respiratory and digestive tracts

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12
Q

• describe the process of neurulation

A

o First, a longitudinal thickening of the ectoderm in the midline of the dorsal aspect of the embryo known as the neural plate
o Next, the cells on the lateral part of the neural plate pile up to form neural folds
 They proliferate, become thicker and migrate dorsally
o Finally, the cells of the neural folds proliferate and migrate so that the two neural folds meet each other dorsally and form an enclosed structure called the neural tube

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13
Q

neural plate

A

 The longitudinally thickened ectoderm in the midline of the dorsal aspect of the embryo
 The lateral aspects become thicker and will form neural folds

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14
Q

Neural folds

A

 Formed by the proliferation of the lateral aspects of the neural plate

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15
Q

Neural groove

A

 The longitudinal gap created between the neural folds

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16
Q

Neural tube

A

 Formed when the cells of the neural folds proliferate and migrate enough that the two folds meet each other dorsally
 Described as an enclosed tube
• The cranial end of the tube will form the brain
• The caudal portion forms the spinal cord
 The cells enclosed are neuroectoderm cells
 The cells that did the enclosing are the surface ectoderm cells

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17
Q

Neuroepithelium

A

• Thick layer of neuroectoderm cells that form the wall of the neural tube

18
Q

Neural Tube Cavity

A
  • The hollow lumen of the neural tube

* Forms the ventricular system of the CNS

19
Q

Rostral neuropore

A

• The front opening of the neural tube that normally closes during week 4

20
Q

Caudal Neuropore

A

• The back opening that also closes during week 4 but a few days later than rostral

21
Q

What happens if any neurpore fails to close?

A

leads to neural tube defects (like spina bifida)

22
Q

• describe how and from what the neural crest forms

A

o formed by neuroectoderm cells that bud off the neural folds
o Forms the basis of the cells of the PNS

23
Q

• list the neural structures that are derived from neural crest cells

A

o Cranial nerve ganglia
o Dorsal root ganglia
o Sympathetic chain and preaortic ganglia
o Parasympathetic ganglia
o Schwann cells
o Leptomeninges (pia and arachnoid mater)

24
Q

• list the three (3) primary brain vesicles and when they form

A

o Definition: three bulges formed in the cranial end of the neural tube
o Prosencephalon (AKA forebrain)
 Most rostral
 Tends to be more horizontal
o Mesencephalon (AKA midbrain)
 Has a forward bend of the neural tube called the cephalic flexure
• Causes the adult brain to have the structure it does
o Rhomboencephalon (AKA hindbrain)
 Caudal to mesencephalon
 Tends to be more vertical

25
Q

• describe the effect of the cephalic flexure on the orientation of the adult structures of the central nervous system

A

o Occurs in the region of the mesencephalon with a forward bend of the neural tube
o Causes the adult brain to have its adult orientation in the skull
o Structures derived from the prosencephalon will have a horizontal arrangement
o Structures derived from the mesencephalon and rhombencephalon will have a verticle orientation

26
Q

• list the five (5) secondary brain vesicles and when they form

A
o	All form during the 5th embryonic week
o	Telecephalon
	From the forebrain
	More rostrally
o	Diencephalon
	From the forebrain
	More caudal
o	Mesencephalon
	No real change from primary brain vesicle
o	Metencephalon
	From hindbrain
	More rostrally
o	Myelencephalon
	From hindbrain
	More caudal
27
Q

• list the structures derived from the neural tube cavity and in which region each is found

A

o Central Canal of the spinal cord
 Formed by the caudal portion of the neural tube cavity in the region of the spinal cord
o 4th ventricle
 Formed in the rhombencephalon
o Cerebral Aqueduct (AKA aqueduct of Sylvius, iter)
 Formed in the region of the mesencephalon
o 3rd ventricle
 Formed in the diencephalon
o Lateral Ventricles (right and left)
 Formed in the telencephalon
 Communicate with the 3rd ventricle by an interventricular foramen (AKA foramen of Monro)

28
Q

ependymal, mantle and marginal layers of the developing neural tube

A

o The caudal portion of the neural tube develops into the spinal cord
o They are formed around the same time that the brain vesicles are forming

29
Q

Ependymal Layer

A

 Innermost (lines the neural tube cavity
 Non-neural layer
 Forms the ependymal cells that line the ventricular system
 Roof and floor plates are derived from this layer

30
Q

Mantle Layer

A

 Intermediate layer
 Contains neuroblasts
• The cells of the neuroepithelium that will form neurons rather than support cells
 Forms the gray matter of the spinal cord

31
Q

Marginal Layer

A

AKA Marginal Zone
 Contains the processes of developing neurons
• Most are axons
• Most get myelinated
 Forms the white matter of the spinal cord

32
Q

• describe the four (4) plates of the developing neural tube, including any functional correlations

A

o Basal Plates (right and left)
 Develop from the mantle layer more ventrally in the neural tube
 The neurons in these plates have motor functions
• Their axons form the ventral roots of the spinal nerves
o Alar plates (right and left)
 Develop from the mantle layer more dorsally in the neural tube
 Neurons in these plates have sensory functions
• They receive axons (PNS neurons) through the dorsal roots of the spinal nerves
o Roof Plate
 Non-paired
 Non-neuronal (no neurons)
 Dorsal portion of the neural tube
o Floor Plate
 Non-paired
 Non-neuronal (no neurons)
 Ventral portion of the neural tube

33
Q

• describe the sulcus limitans

A

o longitudinal groove along the lateral wall of the neural tube cavity
o between the basal and alar plates

34
Q

• describe the ventral and dorsal roots of a spinal nerve, including what type of information each carries and with which plate of the neural tube each is associated

A
o	Ventral root
	Anterior
	Motor root
	Axons are from the basal plates
o	Dorsal Root
	Posterior
	Sensory Root
	Axons  are from the PNS neurons
35
Q

• list the adult derivatives of the three (3) primary and five (5) secondary brain vesicles

A
o	Primary
	Prosencephalon (Forebrain)
	Mesencephalon (midbrain)
	Rhombencephalon (hindbrain)
o	Secondary
	Telecephalon
	Diencephalon
	Mesencephalon (unless otherwise specified this term refers to the secondary brain structure, not the primary)
	Metencephalon
	Myelencephalon
36
Q

• Describe what forms from the secondary brain structures (I ADDED THIS OBJECTIVE)

A
	Telecephalon (horizontal orientation)
•	Forms the cerebrum (bulk of the human brain)
	Diencephalon (horizontal orientation)
•	Epithalamus (including pineal gland)
•	Thalamus
•	Hypothalamus
•	Posterior Pituitary
	Mesencephalon – vertical orientation (unless otherwise specified this term refers to the secondary brain structure, not the primary)
•	Tegmentum (of the midbrain)
•	Tectum (of the midbrain)
	Metencephalon (vertical orientation)
•	Pons
•	Cerebellum
	Myelencephalon (vertical orientation)
•	Medulla (oblongata)
37
Q

• describe the orientation of the general parts of the adult CNS in terms of: anterior/posterior, superior/inferior, rostral (cranial)/caudal, ventral/dorsal

A
o	Differences in orientation are caused by the bending of the neural tube in the sagittal plane between the prosencephalon and the mesencephalon during the 4th embryonic week
	The telencephalon and diencephalon are oriented at a 90 degree angle in regards to the other three secondary brain structures
o	Ventral
	Towards the belly
o	Dorsal
	Towards the back
o	Rostral
	Towards the beak
o	Caudal
	Towards the tail
38
Q

Horizontal Structures orientations

A
(telencephalon and diencephalon)
	Rostral=anterior
	Caudal=posterior
	Dorsal=Superior
	Ventral=Inferior
39
Q

Vertical Structures orientation

A
o	Vertical Structures (mesencephalon, metencephalon, myelencephalon – all three together are the brain stem)
	Rostral=superior
	Caudal=inferior
	Ventral=anterior
	Dorsal=posterior
40
Q

Neuropil

A

Neuropil – the mass of fibers in the gray matter