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Neuroanatomy > Cells and Cytoarchitecture of the Nervous System > Flashcards

Cells and Cytoarchitecture of the Nervous System Flashcards

1
Q

Principal cells in CNS

A 
Neurons 
Glial cells 
-Astrocytes
-Oligodendrocytes
-Microglia
-Ependymal cells
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2
Q

Neurons

A

Receive info by synapses, transmit info

Multipolar with many dendrites to one axon

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3
Q

Group of neurons outside CNS

A

Ganglion

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4
Q

Characteristics of neuons

A 
Cell body (soma) - nucleus and cell organelles
Axon - long process
Dendrites - numerous, short branched processes
Synapses- specialised junctions
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5
Q

Axon arises from swelling in soma called

A

Axon hillock

Leads to initial segmentation of axon (APs arise here)

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6
Q

Pyramidal cell

A

Lots of dendrites

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7
Q

Multipolar

A

Common, many dendrites 1 axon

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8
Q

Bipolar

A

1 dendrite 1 axon

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9
Q

Pseudopolar

A

Short processes give rise to axons in both directions

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10
Q

What is axonal transport?

A

Energy consuming mechanism to move material up and down the axon

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11
Q

How does axonal transport work?

A

Molecular motors such as kinesin = microtubules attach organelles, vesicles etc.

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12
Q

Anterograde axonal transport

A

Fast axonal transport
400 mm/day
Move away from soma

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13
Q

Retrograde axonal transport

A

200 mm/day

towards soma

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14
Q

Neurophil

A

Neuronal and glial cell processes containing myriad synaptic contacts

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15
Q

Another name for presynaptic axon terminal

A

Terminal bouton

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16
Q

Glial cells

A

10 times more numerous in CNS than neurons

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17
Q

Astrocytes

A 
FORMATION OF BLOOD BRAIN BARRIER
Many processes
Star shaped 
Scaffolding 
Surround synapses
Processes found near synapses 
Guide migration of cells and processes
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18
Q

How do unmyelinated axons and nodes of ranvier maintain extracellular movement

A

Absorb K+

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19
Q

Fibrous astrocytes

A

Common in white matter
Fewer processes
Processes are long and thin

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20
Q

Protoplasmic astrocytes

A

Most common in grey matter

Lots of short branching processes

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21
Q

Astrocytes have intermediate filaments in their cytoplasm what are they made of?

A

GFAP- glial fibrilary acidic protein

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22
Q

Astrocytes end in flattened processes called

A

Endfeet
do not have tight junctions, so do not form the actual BBB,
Induce the capillary endothelium to form tight junctions and these tight junctions between the capillary endothelial cells form the heart of the BBB.

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23
Q

Astrocytes send similar endfeets forming a covering below pia and ependymal lining of ventricles this is

A

Glia limitans

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24
Q

Oligodendrocytes

A

Produce myelin ONLY IN CNS
Small round cells
Numerous processes extending to produce internodes of myelin
Round nucleus

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25
Q

One oligodendrocyte produces

A

Several internodes of myelin (CNS)

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26
Q

One schwann cell

A

Single shealth (PNS)

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27
Q

Microglia

A

Similar to macrophages
Immune monitoring and antigen presentation
Brain = slow rate of lymphoid cell traficking
Resting state = elongated nucleus, short spiny cell processes
When activated become rounder
Express MHC class II proteins
Smallest glial cells

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28
Q

Perivascular macrophages are found

A

around blood vessels

On vascular side of basal lamina

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29
Q

Ependymal cell

A

Cuboidal/columnar epithelium-like cells that line the ventricles
Ependymocytes form majority of epndymal lining
Lack basal lamina therefore not true epithelia
Basally they interdigitate with astrocyte processes of the glia limitans. Apically they lack tight junctions, and this allows free exchange between the CSF and the CNS parenchyma.

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30
Q

Tanycytes

A

Small, specialised subset of ependymocytes
Found in the ependyma lining the floor of the 3rd ventricle.
Lack a blood-brain barrier=circumventricular organs.
Long processes from the tanycytes contact these blood vessels, including those of the hypothalamic-hypophyseal portal system, and these cells are thought to play a role in monitoring hormone levels in the CSF and responding by discharging secretory products into capillaries, perhaps to control secretion from the anterior pituitary.

31
Q

Choroid Plexus

A

villous structure with a core of blood vessels covered by a layer of pia mater and an outer layer of choroid epithelium, which are modified ependymal cells.
Cuboidal cells have long microvilli on their surface. Tight junctions between them = BLOOD- CSF BARRIER.
Secrete CSF.

32
Q

Neuron cell bodies

A

Large with abundant cytoplasm and Nissl substance and large nuclei

33
Q

Support cells- satellite cells & Schwann cells.

A

small cells which surround the neuronal cell body

34
Q

PNS

A 
Neuron cell bodies
Support cells
Axons
Loose fibrocollagenous CT
Dorsal root ganglia and autonomic root ganglia
35
Q

Dorsal root ganglion

A

Pseudounipolar therefore no synapses

36
Q

Autonomic root ganglion

A

Synapses present

37
Q

What is a nerve

A

collection of axons linked together by support tissue into an anatomically defined trunk. The axons may be either motor (efferent) or sensory (afferent), and can be myelinated or unmyelinated

38
Q

Peripheral nerve composed of

A
  1. Axons
  2. Schwann cells, some of which produce myelin.
  3. Fibroblasts which produce fibrocollagenous material.
  4. Blood vessels
39
Q

What is a fascicle?

A

Several bundles of axons

40
Q

What is Epineurium

A

CT sheath surrounding whole nerve

41
Q

What is perineurium

A

CT sheath surrounding fasicle

42
Q

What is endoneurium

A

CT sheath surrounding fibres within a fasicle

43
Q

The blood-nerve barrier

A

consists of tight junctions in the intrafascicular capillaries and tight junctions between cells in the perineurium.

44
Q

Schwann cells

A

Larger axons myelinated by these
Form a single internode of myelin around 1 axon
Derived from neural crest cells produce a basal lamina

45
Q

Remak bundles

A

Smaller axons embedded in clefts of cytoplasms of Schwann cell unmyelinated groups

46
Q

Satellite cells

A

Flat epithelia like cells surrounding neurons in sensory and autonomic ganglia

47
Q

Myelin sheath

A

Made of multiple layers of lipid rich membrane
Special adhesion proteins and lipids
220mph

48
Q

PNS myelin sheath

A

Formed by schwann cells

49
Q

CNS myelin sheath

A

Oligodendrocytes makes myelin around many axons

50
Q

Schmidt-Lanterman incisures (or clefts)

A

Strip of cytoplasm across sheath as helical spiral

Allow transport of molecules across sheath

51
Q

Node of Ranvier

A

Break in myelin

52
Q

Internode

A

Length of axon covered by myelin

Typically 1um

53
Q

Saltatory conduction

A

Increases speed of conduction by 100 fold

54
Q

Motor neurons axons end in

A

NMJ on voluntary muscle(SMS)

Form synapses with smooth muscle (ANS)

55
Q

Merkel disc

A

Very sensitive to tissue displacement and widely distributed in skin and some mucosae

56
Q

Ruffini ending

A

Found in glabrous skin, mainly responds to skin stretch

57
Q

Pacinian corpuscle

A

Sensitive to deep pressure.
Found deep in dermis. 20-60 lamellae of CT separated by gelatinous material.
Up to 1mm in length.

58
Q

Meissner’s corpuscle

A

Sensitive to light touch. Widely distributed, but concentrated in areas like fingertips and tongue. Located in the dermal papillae.

59
Q

NMJ

A

Presynaptic terminal and motor end plate

60
Q

Allocortex

A

Archiocortex - hippocampus

Paleocortex - olfactory cortex

61
Q

Neocortex

A

6 layers

62
Q

Cortical neurons

A

Principal cells and interneurons

63
Q

Principal cells

A

Pyramidal cells, fusiform cells - project to thalamus
Excitatory
Axonal process of these are not confined to cortex

64
Q

Interneurons

A

Spiny stellate cells (excitory)
Non-spiny cells (inhibitory)
–basket, fusiform, horizontal and martinotti cells

65
Q

Pyramidal cells

A

Triangular
Apex towards surface of brain
Single long apical dendrite towards cortical surface and basal dendrites extend horizontally.
Single axon from basal surface from grey matter to white matter

66
Q

Molecular layer (I) most sup

A

Few cells

Horizontal axons and dendrites of afferents, intercortical neurons and apical dendrites of pyramidal cells

67
Q

External granular layer (II)

A

Many small neurons (interneurons and small pyramidal cells)

68
Q

External Pyramidal layer (III)

A

Pyramidal cells
Axons project to other parts of the cortex
Get larger as go down the layer

69
Q

Internal granular layer (IV)

A

Stellate cells

70
Q

Internal pyramidal layer (V)

A

Large pyramidal cells
Project to subcortical layers (BS and SC)
Primary motor cortex = giant cells (100um)= betz cells

71
Q

Multiform layer VI

A

Different cell types

Fusiform project to thalamus

72
Q

Cortical columns

A

200-500um D
Respond to peripheral stimulus
In primary sensory cortices (visual cortex)

73
Q

Cerebellar cortex

A 
3 layers (sup to deep)
Molecular
Purkinje cell
Granule cell
White matter

Neuroanatomy (11 decks)

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