LEC 9: Histology of the Nervous System - 08.22.14 Flashcards Preview

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Flashcards in LEC 9: Histology of the Nervous System - 08.22.14 Deck (43):
1

From which embryological structure does the CNS develop and what does it include

  • develops from neural tube
  • Includes:
    • brain (cerebrum and brainstem)
    • spinal cord

2

From which embryological structure does the PNS develop and what does it include

  • neural crest derivative
  • includes: 
    • spinal (sensory and motor) nerves
    • sensory ganglia
    • Schwann cells
    • Autonomic nervous system
      • sympathetic
      • parasympathetic
      • enteric

3

What are the two (2) main parts of the brain

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1. cerebrum

2. brainstem

4

What are the three (3) layers of meninges covering the CNS

1. Dura mater

  • tough, fibrous, protects brain inside skull

2. Arachnoid mater

  • arachnoid trabeculae are connective tissue channels that connect arachnoid and pia 
  • blood vessels go through arachnoid
  • arachnoid approximates brain surface

3. Pia Mater

  • follows every nook and cranny of brain

5

meningiomas

tumors in meninges (pia, arachnoid, dura)

6

Ventricular System

fluid filled sac that is the internal core of CNS; filled with CSF, which is produced by the choroid plexus

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7

ependymoma

tumors of ependymal cells

8

Ciliated ependymal cells

brain ventricles (ventricular system) are lined by ciliated ependymal cells; promote movement of CSF

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9

Four (4) cellular constituents of the CNS

1. neurons (nerve cells)

2. glia (supporting cells)

3. capillaries

4. ependymal cells

10

Parts of a neuron

1. one or more dendrites

  • information/signal receivers

2. a cell body (soma)

  • metabollic support, sums info received

3. one axon

  • transmits message

Neurons are structurally and functionally polarized

11

Neuronal subtypes, categorized by relationship between cell body and its processes

1. multipolar neurons

  • throughout nervous system

2. bipolar neurons

  • only a few places (retina, C8 nerve which controls audio)

3. unipolar neurons

  • found only in sensory ganglia (info coming from skin, muscles, etc.)

 

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12

Neuronal subtypes, categorized by cell body shape and dendritic process morphology

1. pyramidal cells

2. spiny stellate cells

Main 2 types of cells of cerebral cortex

13

Role of spines along axon of pyramidal cells

change with experience, learning, memory, cognition, plasticity, hormones, aging

14

Neuronal subtypes, categorized on the basis of the axon

1. long axon projection neurons

  • to other neurons
  • to effectors (muscles, glands)

2. short axon interneurons

  • amacrine cells (interneurons in retina)

15

functions of cells with short axons (or no axon, as in amacrine cells)

local circuit neurons (e.g. retina)

16

Two (2) parts of the axonal ending

1. telodendron

2. terminal boutons

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17

What are the major organelles found in axon terminals

1. mitochondria (ATP)

2. synaptic vesicles (contain neurotransmitter molecules)

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18

Components of synapses

1. presynaptic membrane (with synaptic vesicles)

2. synaptic cleft

3. postsynaptic membrane

NB: can also have axo-spinous synapses

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19

Neuromuscular Junction

  • motor end plate is an enlarged terminal with:
    • synaptic vesicles
    • junctional folds
    • enlarged synaptic cleft
    • muscle sole plate
  • end plate is covered by lemmocyte cytoplasm and basal lamina

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20

nissl bodies

large glandular body found in neurons; actually RER with rosettes of free ribosomes

 

NB: spinal cord motor neurons have a prominent nucleus and lots of nissl

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21

Lower motor neuron diseases

  • polio
  • ALS

 

22

Motor neuron diseases

  • Parkinson's disease and related disorders
  • Huntington's disease
  • Alzheimer's disease and other dementias
  • Prion disease
  • Spinocerebellar ataxia
  • Spinal muscular atorphy

23

Three (3) types of neuronal cell death

1. apoptosis (programmed cell death)

2. necrosis/cytoplasmic

3. authophagy

24

Glia cells

support cells of neuronal cells

25

Three (3) types of glial cells

1. astrocytes

2. oligodendrocytes

3. microglia

26

astrocytes

Protoplasmic, fibrous

  • structural support
  • metabolic support
  • contribute to blood/brain barrier
  • form CNS scar tissue
  • provide scaffolding for neuronal migration and axon guidance
  • may participate in signal processing and memory encoding
  • scavenge neurotransmitters
  • send linings around capillaries

27

oligodendrocytes

form CNS myelin

28

microglia

CNS macrophages (exist in resting state, then activated to fight infection)

29

Astrocytes and the blood brain barrier

astrocytic perivascular endfeet wrap around capillaries to protect brain from blood (may have disease in it)

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30

What do oligodendrocyte processes form

CNS myelin

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31

Nodes of Ranvier

breaks in the myelin, contributes to saltatory conduction (very rapid transmission of info)

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32

Multiple schlerosis

a demyelinating disease; plaques = absence of myelin

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33

myelin in CNS vs. myelin in PNS

  • axons myelinated by oligodendrocytes in CNS
  • axons myelinated by Schwann cells in PNS

 

34

Schwann cells

also called neurolemmocytes

35

non-myelinated nerve fibers

vs.

myelinated nerve fibers 

  • non-myelinated nerve fibers are invested with neurolemmocytes (Schwann cells) alone
  • myelinated nerve fibers are invested with neurolemmocytes and several layers of connective tissue

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36

Schwannoma

a benign encapsulted tumor orginating from Schwann cells

37

Nodes of Ranvier in CNS

vs.

Nodes of Ranvier in PNS

  • in CNS, Nodes of Ranvier are exposed to extracellular space
  • in PNS, Nodes of Ranvier are covered by cytoplasmic processes from adjacent lemocytes

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38

Connective tissue associated with a peripheral nerve

  • all PNS axons are invested with Schwann cells
  • Schwann cells surrounded by endoneurium
  • endoneurium surrounded by perineurium, with is lined with perineural epitheliod cells (perineural epithelium)
  • each nerve fasicle surrounded by perineurium
  • nerves are composed of multiple fasicles
  • whole nerve (all fasicles) is enveloped by epineurium

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39

What connective tissue surrounds Schwann cells

endoneurium

40

What is perineurium

surrounds endoneurium, lined with perineural epitheliod cells to form perineural epithelium

41

perineural epithelium

perineurium (which surrounds endoneurium) is lined with perineural epitheliod cells

42

What are nerve fasicles surrounded by

perineurium

43

nerves are composed of multiple fasicles; what surrounds all the fasicles together

epineurium