Histology (11/6) Flashcards Preview

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Flashcards in Histology (11/6) Deck (66)
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1

Embryology of Nervous System

Neural crest
PNS: sensory neurons of spinal & cranial ganglia; motor neurons of autonomic ganglia; glia of the PNS; other “non-neuronal” cell types

Neural tube
Neurons & glia of CNS

2

Mitotic potential of NS cells

Neurons are non-mitotic

Glial cells maintain mitotic capability

3

White Matter

Aggregations of axons, includes nerves in PNS and tracts, columns, fasciculi of axons in CNS, white d/t myelination

4

Gray Matter

AGgregations of nerve cell bodies + neuropil
Ganglia in PNS, nuclei etc in CNS
Gray d/t little myelin

5

Neuropil

complex network of nerve cell processes, synapses, and glial cells occupying intervals between nerve cell bodies in gray

6

Constituents of Nervous Tissue: CNS

Nerve cells
Glia: Astrocytes, oligodendrocytes, Microglia, ependymal cells
Blood vessels

7

Constituents of Nervous Tissue: PNS

Nerve cells
Glia: Schwann cells, Satellite cells
Blood vessels
connective tisse

8

General Cytology/Components of Nerve Cell

Plasma membrane, cell body, Dendrites, (Sensory receptors), axon, end terminal

9

RER in nerve cells

Nissl bodies
Extensive - present throughout whole cell body + dendrites, absent from axon hillock + axon

10

Golgi in Neurons

Just in cell body
Package vesicles (full or empty) to send down axon

11

Neurofilaments

Type of intermediate filament found only in neurons - structural role - form neurofibrils - found in body and processes

12

Microtubules in neurons

Involved in transport of molecules/particles down axon (maybe growth and development)

13

Microfilaments in neurons

Specialized distribution (growth cones, some junctions)

14

Pigments in Neurons

Lipofuscin - insoluble remnants of lysosomes (product of digestion) - golden brown
Neuromelanin - naturally occuring in some areas, dark brown/black

15

Mitochondria in Neurons

Large numbers throughout cells, especially abundant in axons

16

Unencapsulated nerve endings (receptors)

Touch, pain (maybe hot/cold)
i.e. merkel cell (Touch)

17

Corpuscles of Ruffini + Krause's end-bulbs

mechanoreceptors, glomerular (encapsulated)

18

Meissner's Corpuscle

Touch
Fibrous capsule (encapsulated)
Found in hairless skin

19

Pacinian Corpuscle

Deep pressure, vibration
Lamellar corpuscle
Looks like onion

20

ABC grades of axons

A - large, myelinated
B - smaller, myelinated
C - smallest, not myelinated

21

Presynaptic dense projections

electron dense material on cytoplasmic side of membrane at axon end terminal
Vesicles approach and fuse with presynaptic membrane (guide into right place)

22

Axonal Transport : Slow

Only orthograde
Carries soluble macromolecules, small molecules not in vesicles, fibrillar components of axoplasm

23

Axonal Transport: Fast

Orthograde faster than retrograde (both much faster than slow), microtubules
Orthograde: vesicles, organelles, etc. - KINESIN --> plus end (faster)
Retrograde: Worn out membranes, etc. - DYNEIN --> minus end

24

Consequences of Retrograde transport

clinically: how viruses (i.e. rabies) get far into nervous system
developmentally: might be how axons are told to grow
experimentally: track process of marker molecules back to find cell bodies

25

Neuroglia of CNS

Astrocytes, Microglia, Oligodendrocytes, Ependymal cells
Outnumber neurons

26

Macroglia

Astrocytes + Oligodendrocytes

27

Types of Astrocytes

Fibrous or Protoplasmic (Golgi staining vs. H&E) - either due to functional states or location

28

Golgi stain appearance of astrocytes

Cell body usually obscured by mass of processes, found near blood vessels/surfaces of brain

29

H&E/Nissl Stain Astrocytes

Nucleus - oval, large

30

Functions of Astrocytes

Terminal end feet --> pervasive between neurons and processes -->
End on blood vessels (maybe induce blood brain barrier)
End on inner surface of pia mater - external glial limiting membrane
End on basal surface of ependymal cells to form internal glial limiting membrane

Structural support, uptake potassium after activity, phagocytosis, Isolation from other neurons, regulation of environment