Histology of the Nervous System Flashcards Preview

MD1 Neuroscience > Histology of the Nervous System > Flashcards

Flashcards in Histology of the Nervous System Deck (78):
1

What is the key cell of the nervous system?

Neuron

2

What are the types of glial cells?

Astrocytes
Oligodendrocytes
Schwann cells
Ependymal cells
Satellite cells of ganglia

3

What are the immune cells of the CNS?

Microglia

4

How many glial cells are there?

Almost as many as neurons

5

How many layers of neurons are there in grey matter?

6

6

What colour does the cell body stain with H&E?

Pink

7

What colour do the processes stain with H&E?

Pink

8

What is highlighted with a silver stain?

Processes

9

What does the ventricular system do?

Form and provide passage for CSF

10

What is the choroid plexus?

Vascular structure arising from ventricles

11

What does the choroid plexus do?

Form CSF

12

What cell type are ependymal cells?

Low columnar or cuboidal

13

Where are ependymal cells found?

Line central canal of spinal cord and ventricles in brain

14

T/F: Ependymal cells in some areas have cilia. If true, why?

True, to help CSF flow

15

Are ependymal cells epithelial or glial?

Neither, but they're more glial than epithelial

16

How are ependymal cells attached to underlying tissue?

Via long processes anchoring cell in tissue

17

What are some characteristics of neurons?

Morphologically distinct
Electrically active
Rapid communication
Long distance
Specialised; eg:
- Retina
- Cochlea
High level of protein synthesis
Metabolically limited
Terminally differentiated

18

Where are Purkinje cells found?

Cerebellar cortex

19

Where are pyramidal cells found?

Cerebral cortex

20

What are the three components of a neuron's cytoskeleton?

Actin
Intermediate filaments
Microtubules

21

What is the role of actin in a neuron's cytoskeleton?

Dynamic assembly/disassembly
Allows shape changes and movement; eg:
- Spines grow during learning
- Growth cones

22

What is the role of intermediate filaments in a neuron's cytoskeleton?

In all processes
Permanent

23

What is the role of microtubules in a neuron's cytoskeleton?

Dynamic
Made of tubulin
Axon transport

24

What does the soma do?

Metabolic centre of cell

25

What are the two types of neuronal processes?

Dendrite
Axon

26

What does a dendrite do?

Receive information from other neurons
= Input

27

What does an axon do?

Main conducting unit for carrying signals to other neurons
= Output

28

Where is a high proportion of total cell volume?

Axons (and dendrites)

29

Why is axonal transport critical?

To supply cell-body derived elements to long axon

30

Which part of the neuron does random damage often involve?

Axon, not cell body

31

Describe graded membrane potentials

Unequal distribution of positively charged ions on either side of membrane
Membrane has Na-K-ATPase pumps and ion channels - sets up charge distribution across membrane

32

What type of signal is sent via dendrites?

Passive spread of current - local signal

33

What type of signal is sent via axons?

Action potential - travels long distances

34

Describe the synapse

Pre-synaptic cell talks to something
- Synaptic vessels contain neurotransmitters
Synaptic cleft = space between communicating processes
Post-synaptic cell receives information > change in membrane potential > responds to information

35

What is the high level of protein production in neurons needed for?

Ion channels
Receptors
Cytoskeleton

36

How do you identify a highly synthetic cell in cytology?

Large pale nucleus
Nissl bodies

37

What are Nissl bodies?

Organelles that make proteins
- Rough ER
- Free ribosomes

38

Where is protein made in a neuron?

Cell body only

39

What is another name for glia?

Macroglia

40

Where are glia derived from?

Neuroectoderm, like neurons

41

Where are microglia derived from?

Bone marrow, like other immune cells

42

What are the passive support functions of astrocytes?

Neurotransmitter uptake and degradation
K homeostasis
Neuronal energy supply
Maintenance of BBB
Injury response and recovery

43

Why is neurotransmitter uptake and degradation important?

Otherwise signal continuous

44

What does too much K in the ECF mean for the neuron?

Overstimulation

45

How is glucose transported across the BBB?

Blood > astrocytes > neurons

46

How do astrocytes contribute to the BBB?

Wrap around blood vessels

47

What are the active functions of astrocytes?

Modulation of neuronal function
Modulation of blood flow

48

Why can astrocytes carry out their active functions?

Electrically coupled
Send signals

49

What type of neurotransmitter is glutamate?

Excitatory

50

What type of neurotransmitter is GABA?

Inhibitory

51

Describe the cycling of glutamate across the synapse

1. Glutamate released into synapse
2. Glutamate detected by glutamate receptor on glial cell
3. Glutamate enters glial cell
4. Converted to glutamine - toxic otherwise
5. Glutamine shunted back to neuron

52

Describe the cycling of GABA across the synapse

1. GABA released into synapse
2. GABA detected by GABA receptors on glial cell
3. GABA enters cell
4. GABA shunted into Krebs cycle
5. Glutamine also shunted to neuron for GABA synthesis

53

What happens when glutamate transporters on glial cells are inhibited?

Neurons depolarise more
Increase in signal strength and duration > too metabolically active > neuronal death

54

What is the intracellular ion that changes in concentration in astrocytes?

Ca

55

What does modulation in IC Ca allow a glial cell to do?

Release of neuronal modulatory substances

56

What initiates Ca modulation in astrocytes?

Neurotransmitters like:
- ATP
- Glutamate
Trauma
Spontaneous
Inflammatory mediators

57

T/F: Glial cells have synaptic vesicles and show exocytosis

True

58

How does an increase in IC Ca in glial cells affect neurons?

Inhibited by Ca wave
Mechanism involves release of ATP from glia

59

How do astrocytes regulate vascular tone?

Ca wave in astrocyte causes vasoconstriction/vasodilation

60

What is the predominant glial cell of white matter?

Oligodendrocyte

61

What do oligodendrocytes do?

Myelinate axons in CNS

62

What do Schwann cells do?

Myelinate axons in PNS

63

Why is myelination important?

Provide electrical insulation
Speeds up conduction

64

What else other than myelination speeds up conduction?

Increased axon diameter

65

How many axons do oligodendrocytes myelinate?

Several

66

How many axons do Schwann cells myelinate?

One

67

What breaks up the myelin sheath?

Nodes of Ranvier

68

What is the role of the nodes of Ranvier in signal transduction?

Signal jumps from node to node
Rapid propagation of signal

69

T/F: CNS is immune priveleged

True

70

What is the role of microglia

Surveillance
Local defence
Brain development
Disease

71

What happens to microglia during inflammation or injury?

Change rapidly
Resemble macrophages

72

Describe the histological structure of a peripheral nerve

Made up of nerve fibres
Each nerve fibre and Schwann cell surrounded by loose vascular supporting tissue = endoneurium
Fascicles = one or more bundles of nerve fibres
Each fascicle surrounded by collagenous tissue = perineurium
Bundles of fascicles wrapped in epineurium

73

What are ganglia?

Aggregations of cell bodies outside of CNS

74

What are the types of ganglia?

Sensory
Autonomic

75

What are sensory ganglia?

House cell bodies of sensory neurons
Eg: dorsal root ganglia

76

What are autonomic ganglia?

House cell bodies of post-ganglionic neurons

77

What makes up ganglia?

Cell bodies
Nerve fibres
Satellite cells

78

What are satellite cells?

Supporting cells in ganglia

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