Embryology: Neurulation & Neural Crest, Histology: Nervous Tissue Flashcards Preview

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Flashcards in Embryology: Neurulation & Neural Crest, Histology: Nervous Tissue Deck (76):
1

What is the somatic nervous system

the nervous system that innervates the skin and most skeletal muscle

2

what is the visceral (autonomic) nervous system

the nervous system that innervates the viscera, smooth muscle, and glands

3

what are the divisions of the visceral/autonomic nervous system

sympathetic and parasympathetic

4

What are the steps in the formation of the neural tube

1. thickening of neural plate
2. elongation of neural plate
3. lateral folding
4. fusion of opposing neural folds
5. separation from overlying ectoderm

5

what is the role of each of these structures in neural tube formation:
notochord
neural groove
neural crest
median hinge point
lateral hinge point
neural crest cells

notochord - lies below the neural groove and signals the formation of the following structures
neural groove - cells that form the first invagination of the neural tube
neural crest - cells that come together to complete the tube formation (remain as free cells outside of tube)
median hinge point - first fold point of the tube
lateral hinge point - two lateral points of folding that bring the neural crests together

6

What are the different primary CNS segments

1. prosencephalon (forebrain)
2. mesencephalon (midbrain)
3. rhombencephalon (hindbrain)
spinal cord

7

how many folds are there in the primary CNS

2 (cephalic and cervical)

8

what are rhombomeres

different segments of the hindbrain caused by HOX genes

9

What are the secondary CNS segments

Prosencephalon
1. telencephalon
2. diencephalon
3. Mesencephalon
Rhombencephalon
4. metencephalon
5. myelencephalon
spinal cord

10

how many folds are there in the secondary CNS

3 (mesencephalic, cervical, pontine)

11

What does the telencephalon develop into (and the neural canal in that area)

cerebral hemispheres (lateral ventricles)

12

What does the diencephalon develop into (and the neural canal in that area)

Thalamus, hypothalamus, pituitary gland, eyes (3rd ventricle)

13

what does the mesencephalon develop into (and the neural canal in that area)

anterior (visual) and posterior (auditory) colliculi (cerebral aquedcut

14

What does the metencephalon develop into

cerebellum, pons

15

what does the myelencephalon develop into

medulla oblongata

16

What happens at the external limiting membrane of the neural tube, and what happens at the lumen side of the neural tube

DNA synthesis occurs at the external limiting membrane
mitotic division occurs at the lumen side

17

What is the first progenitor cell in the CNS

neuroepithelium

18

what are the steps of differentiation of CNS cells

1. neuroepithelium
2. multipotential stem cell
3. Bipotential progenitor cell
4a. neuronal lineage progenitor cell
- mature neuron
- microglial cell
4b. Glial lineage progenitor cell
- oligodendrocyte
- type 2 astrocyte
- type 1 astrocyte
- special glial cells
- ependymal cells

19

What happens in the development of mature neuron

they have outgrowths called filopodia that extend and retract (testing the environment) that develop into axons and dendrites

20

what are the two divisions of the brain

brain stem = myelencephalon, pons, and mesencephalon
higher centers = cerebellum and forebrain

21

what are the steps in the development of the thalamus and hypothalamus (pineal gland)

1. swellings on the inner diencephalon with the hypothalamic sulcus between them
2. sulcus dorsus separates the thalamus from the epithalamic swelling
3. thalamic swellings grow and connect via interthalamic adhesions
4. pineal gland forms from a midline diverticulum off of the epithalamic roof plate

22

what are the steps in the development of the pituitary gland

1. infundibulum develops from the floor of the 3rd ventricle
2. Rathkes pouch forms from the ectoderm lined space near future mouth
3. move toward each other. and join
4. rathkes pouch breaks off
5. both move into the sella turcica

23

what forms the anterior pituitary, and what forms the posterior pituitary

infundibulum turns into posterior pit
rathkes pouch turns into anterior pit

24

what is the mesencephalon largely made up of

white matter, tracts that connect the forebrain and hindbrain

25

What does the lumen of the neural tube associated with the mesencephalon develop into

the cerebral aqueduct

26

what happens if the cerebral aqueduct becomes blocked

hydrocephalus (fluid accumulation in the brain)

27

what things develop into the pons

rhabdomeres 1 and 2 and cerebellum

28

what is the function of the pons

relay signals linking the spinal cord with the cerebral cortex and cerebellum

29

what are the pontine nuclei

the part of the pons that relays input from the cerebrum to the cerebellum

30

What things develop into the cerebellum

metencephalon and the adjacent rhombic lips

31

what is the function of the cerebellum

center for balance and posture

32

what are the steps in formation of the cerebellum

1. paired cerebellar plates form
2. cranial portions meet and cover 4th ventricle
3. dumbell shaped swelling forms
4. cranial and caudal portions are separated by posterolateral fissure
5. fissures, folding = lobes with transverse fissures and vermis

33

what develops into the medulla oblongata

the myelencephalon (rhabdomeres 3-8)

34

what is the function of the medulla oblongata

it is the relay center between the spinal cord and higher brain centers

35

what does the medulla oblongata regulate

respiration, heartbeat, reflex movements

36

What are the steps in formation of the peripheral nerves

1. outgrowth of axons from motor neuroblasts in the basal plate
2. neural crest cells form the spinal ganlion with their axons growing toward the dorsal horn and their dendrites growing toward periphery
3. interneurons grow between sensory nerve termination and motor neurons
4. reflex arc forms (sensory information leading strait into motor response)

37

what forms all sympathetic and parasympathetic ganglia

neural crest cells

38

What is hirschsprungs disease

when NCC's fail to colonize in the wall of lower colon (parasympathtic) which means there is no parasympathetic innervation which means no peristalsis which means constipation

39

What is myelination and how does it happen

it is when a schwann cell (NCC derivative) wraps around the nerve and insulates it

40

what happens with unmyelinated cells

they are embedded in non-spiral schwann cells

41

what are the two main kinds of peripheral neuropathies

axonal degeneration and demyelination

42

what type of peripheral neuropathy is charcot-marie-tooth

demyelinating (slows nerve conduction)

43

what is a neurite

an outgrowth, axon or dendrite

44

what are the steps in the growth of an axon

1. pioneering axon grows to a target
2. other axons follow
3. a bundle of axons form (fascicles)

45

Where do NCC's originate from

the lateral margins of the neural plate

46

How do NCC's migrate?

as mesenchymal cells, they change their shape, lose CAMS, and gain integrins. they travel through well defined pathways (CAMS come back upon destination)

47

what determines differentiation of NCC's

environment determined upon arrival, internal factors before migration

48

what are the three main divisions of NCCS

1. crainial
2. circumpharyngeal
3. Trunk

49

what are the things to remember about cranial NCC's

they leave before the neural tube closes
the origin specifies the destination
they are responsible for the tissues of the facial region

50

what are the things to remember about circumpharyngeal NCC's

they migrate in two groups (vagal and cardiac)
Vagal - migrate into gut and are precursors to parasympathetic innervation
Cardiac - outflow of the heart and great vessels, associate with thymus, thyroid and parathyroid

51

what are the things to remember about trunk NCC's

they leave after the neural tube closes
they migrate in three pathways (dorsolateral, ventrolateral, ventral)
dorsolateral - melanocytes
ventrolateral - sensory ganglia
ventral - adrenal chromaffin cells, sympathetic ganglia and neurons

52

what are neurocristopathies

defects of NCC development

53

what is neurofibromatosis

peripheral nerve tumors

54

what is albinism

pigmentation defect

55

what is diGeorge syndrome

defects in development of craniofacial and cardiovascular system

56

what causes the nervous system to work

action potentials send messages to the body

57

what are the components of the nervous system

brain, spinal cord, nerves, supporting cells

58

what are the divisions of the Nervous system

CNS
PNS
- sensory
- somatic
- visceral
- motor
- somatic
- autonomic
- para, and sympathetic

59

what do neuroglial cells do

provide neuronal support and nutrition
maintain homeostasis
forms myelin
participates in transmission

60

what are the 4 neuron characteristics

conducting potential
longevity
amitotic
high metabolic rate

61

What is the soma

cell body (nucleus and organelles), they make up the gray matter

62

what are clusters of cell bodies called in the CNS and PNS

CNS = nuclei
PNS = ganglia

63

what is a synapse

the junction where an axon bulb interacts with another neuron or effector organ

64

what are the three main parts of a synapse

presynaptic neuron
synaptic cleft
postsynaptic neuron

65

what is the resting potential of a neuron

-70 mV

66

What are bipolar neurons for

special senses

67

what are unipolar neurons for

sensory PNS, taste

68

what are multipolar neurons for

motor neurons and interneurons

69

what are the 6 types of glial cells

astrocytes - most common (blood brain barrier, assists in migration)
oligodendrocytes (produce myelin for many neurons)
microglia (macrophages of the CNS)
ependymal cells (line the fluid filled ventricles, create CSF, move it with cilia)
schwann cells (PNS myelination)
satellite cells (surrounds cells in the ganglia, stucture and metabolic help)

70

what are the layers of PNS connective tissue coverings

endoneurium (surrounds axons)
perineurium (holds groups of fibers into fascicles)
epineurium (holds the fascicles together)

71

What are the three meningous layers

Dura mater - dense simple squamous epithelium
Arachnoid mater - trabeculae attach to pia, create space, hydraulic cushion, no Blood vessels
Pia mater - many blood vessels

72

What are the layers of the cerebrum from superficial to deep

molecular
external granular
outer pyrimidal
inner granular
inner pyrimidal
multiform

73

what are the two layers of the cerebellum

cortex - outer molecular - inner granular
medulla - white matter and glial cells

74

where does the spinal cord end

between the 1st and 2nd lumbar vertebrae

75

what are PNS nerve fibers, nerves,

nerve fibers are individual cell axons
nerves are bundles of nerve fibers

76

how many peripheral nerves are there

12 cranial nerve pairs
31 spinal nerve pairs