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Flashcards in Cells of the CNS Deck (64):
1

What is the broad function of glial cells?

Support neurons

2

List 5 types of glial cells?

Astrocytes
Oligodendrocytes
Schwann cells
Ependymal cells
Satellite cells of ganglia

3

What are microglia?

Immune cells

4

What are macroglia?

Refers to glial cells

5

How many layers are there in the cerebral cortex?

6

6

What lies in the six layers of the cerebral cortex?

Cell bodies of neurons and glia

7

What is the function of the ventricular system?

Formation and passage of CSF

8

What is the choroid plexus?

Vascular structure arising from wall of each ventricle

9

What is the function of the choroid plexus?

Forms CSF

10

Describe the structure of ependymal cells?

Columnar or cuboidal cells
Sometimes ciliated
Non basal laminar (different to epithelial cells)

11

Where are ependymal cells found?

Lining central canal of spinal cord and ventricles

12

Why are ependymal cells sometimes ciliated?

Aid CSF flow

13

Why are neurons highly synthetic?

High level of protein synthesis, for structures such as ion channels, receptors and cytoskeleton

14

Describe the metabolic characteristics of neurons?

Metabolically limited

15

Are neurons capable of turning over?

Most are terminally differentiated

16

What are the three components of the cytoskeleton of neurons?

Actin
Intermediate filaments
Microtubules

17

What is the role of actin in neurons?

Shape changes allowed by rapid assembly/disassembly of actin

18

What is the role of microtubules in neurons?

Axon transport

19

What are microtubules composed of in neurons?

Tubulin

20

Describe the volume distribution of neurons?
What is the consequence of this?

High proportion is axon and dendrites
So, random damage often involves axon (prone to damage due to length)

21

What are Nissl bodies?

Large granular body in neurons
Contains RER and free ribosomes

22

How can the high level of protein synthesis in neurons be demonstrated in cytology?

Presence of Nissl bodies

23

How is protein supplied to the distal extremities of neurons?

Axonal transport

24

What are glial cells sometimes called?

Macroglia

25

What is the most important glial cell type in the brain?

Astrocytes

26

List the passive support functions of astrocytes?

NT uptake and degradation
K homeostasis
Neuronal energy supply
BBB maintenance
Injury response and recovery

27

List the active functions of astrocytes?

Modulation of neuronal function
Modulation of blood flow

28

Which particular NTs do astrocytes uptake and degrade?

Glutamate and GABA

29

Describe how astrocytes are involved in K homeostasis/

K released when neuron depolarises
Glial cells suck up excess

30

Is glutamate excitatory or inhibitory?

Excitatory

31

Is GABA excitatory or inhibitory?

Inhibitory

32

What are the most important NTs in the brain?

Glutamate and GABA

33

What do astrocytes express transporters for?

Glutamate and GABA transporters
For reuptake

34

What happens if glutamate transporters are blocked from working? Why?

Massive increase in depolarisation
Neuron is also depolarised for longer period of time
(Because more glutamate remains in synapse for longer)

35

Why are glutamate transporters on glial cells so important?

Removal of glutamate is crucial for maintaining normal function and integrity
If glutamate remains in the synapse, it will continually stimulate the neuron,. which can lead to cell death

36

By what mechanism do glial cells communicate with each other?

Ca waves
Synaptic vesicles - exocytosis

37

What can initiate Ca waves in glial cells?

NTs
Trauma
Spontaneous
Inflammatory mediators

38

How/why are glial cells excitable?

Mechanisms that involve Ca

39

To what extent do glial cells contain and release synaptic vessels/

Very small number

40

How are neurons inhibited?

Ca wave

41

What is the mechanism of neuron inhibition involving glial cells? How are glial cells able to act in this way?

ATP release from glial cells > Ca wave > hyperpolarisation
Glial cells are able to directly modulate the function of neurons in their vicinity

42

How can glial cells regulate neuronal function?

Can directly modulate neurons in their vicinity by release of ATP > Ca wave > hyperpolarisation

43

How can glial cells regulate vasculature?

Can regulate vascular tone via initiation of Ca wave > vasoconstriction or vasodilation
(BV constricts as Ca wave moves closer)

44

How do astrocytes know when to regulate vascular tone?

Astrocyte can sense what is going on at synapse, and alters blood flow in accordance with level of activity and energy requirements

45

Which cell types are involved in myelination?

Oligodendrocytes
Schwann cells

46

What is the predominate cell type of white matter?

Oligodendrocytes

47

What is the role of oligodendrocytes?

Myelinate axons in CNS

48

What is the role of Schwann cells?

Myelinate axons in PNS

49

What are the differences between oligodendrocytes and Schwann cells?

1. Oligodendrocytes - CNS; Schwann cell - PNS
2. Oligodendrocytes extend processes that wrap around several axons; Schwann cells wrap around a single axon

50

What are the immune cells of the CNS called?

Microglia

51

Where do microglia arise from?

Bone marrow

52

What immune cell type do microglia resemble?

Macrophages, as they are phagocytic

53

Describe the action of microglia?

Local defence cells
Constantly survey the CNS by extending processes
Are phagocytic

54

When do microglia change?

Change in response to inflammation or injury

55

How do microglia change in response to inflammation or injury?

Upregulate cytokines and growth factors

56

Describe the broad structure of peripheral nerves?

Each nerve fibre surrounded by endoneurium
Bundles of nerve fibres form fascicles
Each fasicle surrounded by perineurium
Bundles of fasicles surrounded by epineurium

57

What does endoneurium enclose?

A nerve fibre and Schwann cell

58

What does epineurium enclose?

Bundles of fascicles

59

What does perineurium enclose?

A fasicle

60

What are ganglia?

Aggregations of neuron cell bodies that lie outside the CNS

61

What are the two types of ganglia?

Sensory and autonomic

62

What do sensory ganglia contain?

Cell bodies of sensory neurons

63

What do autonomic ganglia contain?

Cell bodies of post-ganglionic neurons

64

Where are the cell bodies of post-ganglionic autonomic neurons found?

In autonomic ganglia