Cells of the CNS

Question 1

What is the broad function of glial cells?

Answer 1

Support neurons

Question 2

List 5 types of glial cells?

Answer 2

Astrocytes
Oligodendrocytes
Schwann cells
Ependymal cells
Satellite cells of ganglia

Question 3

What are microglia?

Answer 3

Immune cells

Question 4

What are macroglia?

Answer 4

Refers to glial cells

Question 5

How many layers are there in the cerebral cortex?

Answer 5

6

Question 6

What lies in the six layers of the cerebral cortex?

Answer 6

Cell bodies of neurons and glia

Question 7

What is the function of the ventricular system?

Answer 7

Formation and passage of CSF

Question 8

What is the choroid plexus?

Answer 8

Vascular structure arising from wall of each ventricle

Question 9

What is the function of the choroid plexus?

Answer 9

Forms CSF

Question 10

Describe the structure of ependymal cells?

Answer 10

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

Question 11

Where are ependymal cells found?

Answer 11

Lining central canal of spinal cord and ventricles

Question 12

Why are ependymal cells sometimes ciliated?

Answer 12

Aid CSF flow

Question 13

Why are neurons highly synthetic?

Answer 13

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

Question 14

Describe the metabolic characteristics of neurons?

Answer 14

Metabolically limited

Question 15

Are neurons capable of turning over?

Answer 15

Most are terminally differentiated

Question 16

What are the three components of the cytoskeleton of neurons?

Answer 16

Actin
Intermediate filaments
Microtubules

Question 17

What is the role of actin in neurons?

Answer 17

Shape changes allowed by rapid assembly/disassembly of actin

Question 18

What is the role of microtubules in neurons?

Answer 18

Axon transport

Question 19

What are microtubules composed of in neurons?

Answer 19

Tubulin

Question 20

Describe the volume distribution of neurons?

What is the consequence of this?

Answer 20

High proportion is axon and dendrites

So, random damage often involves axon (prone to damage due to length)

Question 21

What are Nissl bodies?

Answer 21

Large granular body in neurons

Contains RER and free ribosomes

Question 22

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

Answer 22

Presence of Nissl bodies

Question 23

How is protein supplied to the distal extremities of neurons?

Answer 23

Axonal transport

Question 24

What are glial cells sometimes called?

Answer 24

Macroglia

Question 25

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

Answer 25

Astrocytes

Question 26

List the passive support functions of astrocytes?

Answer 26

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

Question 27

List the active functions of astrocytes?

Answer 27

Modulation of neuronal function | Modulation of blood flow

Question 28

Which particular NTs do astrocytes uptake and degrade?

Answer 28

Glutamate and GABA

Question 29

Describe how astrocytes are involved in K homeostasis/

Answer 29

K released when neuron depolarises | Glial cells suck up excess

Question 30

Is glutamate excitatory or inhibitory?

Answer 30

Excitatory

Question 31

Is GABA excitatory or inhibitory?

Answer 31

Inhibitory

Question 32

What are the most important NTs in the brain?

Answer 32

Glutamate and GABA

Question 33

What do astrocytes express transporters for?

Answer 33

Glutamate and GABA transporters | For reuptake

Question 34

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

Answer 34

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

Question 35

Why are glutamate transporters on glial cells so important?

Answer 35

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

Question 36

By what mechanism do glial cells communicate with each other?

Answer 36

Ca waves | Synaptic vesicles - exocytosis

Question 37

What can initiate Ca waves in glial cells?

Answer 37

NTs Trauma Spontaneous Inflammatory mediators

Question 38

How/why are glial cells excitable?

Answer 38

Mechanisms that involve Ca

Question 39

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

Answer 39

Very small number

Question 40

How are neurons inhibited?

Answer 40

Ca wave

Question 41

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

Answer 41

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

Question 42

How can glial cells regulate neuronal function?

Answer 42

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

Question 43

How can glial cells regulate vasculature?

Answer 43

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

Question 44

How do astrocytes know when to regulate vascular tone?

Answer 44

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

Question 45

Which cell types are involved in myelination?

Answer 45

Oligodendrocytes | Schwann cells

Question 46

What is the predominate cell type of white matter?

Answer 46

Oligodendrocytes

Question 47

What is the role of oligodendrocytes?

Answer 47

Myelinate axons in CNS

Question 48

What is the role of Schwann cells?

Answer 48

Myelinate axons in PNS

Question 49

What are the differences between oligodendrocytes and Schwann cells?

Answer 49

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

Question 50

What are the immune cells of the CNS called?

Answer 50

Microglia

Question 51

Where do microglia arise from?

Answer 51

Bone marrow

Question 52

What immune cell type do microglia resemble?

Answer 52

Macrophages, as they are phagocytic

Question 53

Describe the action of microglia?

Answer 53

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

Question 54

When do microglia change?

Answer 54

Change in response to inflammation or injury

Question 55

How do microglia change in response to inflammation or injury?

Answer 55

Upregulate cytokines and growth factors

Question 56

Describe the broad structure of peripheral nerves?

Answer 56

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

Question 57

What does endoneurium enclose?

Answer 57

A nerve fibre and Schwann cell

Question 58

What does epineurium enclose?

Answer 58

Bundles of fascicles

Question 59

What does perineurium enclose?

Answer 59

A fasicle

Question 60

What are ganglia?

Answer 60

Aggregations of neuron cell bodies that lie outside the CNS

Question 61

What are the two types of ganglia?

Answer 61

Sensory and autonomic

Question 62

What do sensory ganglia contain?

Answer 62

Cell bodies of sensory neurons

Question 63

What do autonomic ganglia contain?

Answer 63

Cell bodies of post-ganglionic neurons

Question 64

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

Answer 64

In autonomic ganglia