W19-L2: Cells of the CNS

Question 1

How many layers of neurones are there in the cortex?

Answer 1

6

Question 2

What is the cortex?

Answer 2

Thin 1 cm layer of cell bodies that is the outermost layer of the brain

Question 3

What stains can you use for neurones

Answer 3

H & E and Silver stain (golgi stain)

Question 4

What are ependymal cells?

Answer 4

Low columnar or cuboidal cells that line the central canal of the spinal cord and the ventricle within the brain.

Question 5

How is CSF flow aided?

Answer 5

cilia on apical surface of ependymal cells

Question 6

What is the difference between ependymal cells and epithelial cells?

Answer 6

ependymal cells have non basal laminar

Question 7

How are neurones different from other cells?

Answer 7

• Neurons are specialized for signalling (Morphologically distinct, Electrically active, Rapid communication, Long distance)
• High level of protein synthesis
• Metabolically limited
• Terminally differentiated

Question 8

Regulation of neuronal morphology

Answer 8

Via the cytoskeleton

Question 9

Actin’s role in neuronal cytoskeleton

Answer 9

Dynamic assembly/disassembly allows shape changes and movement (e.g spines and growth cones)

Question 10

Intermediate filament’s role in neuronal cytoskeleton

Answer 10

• In all processes

- permanent

Question 11

Microtubule’s role in neuronal cytoskeleton

Answer 11

• Dynamic
• Composed of tubulin
• Axon transport

Question 12

How are high levels of protein production seen?

Answer 12

large pale nucleus, Nissl bodies (rough ER, free ribosomes)

Question 13

Most important function of astrocytes

Answer 13

Neurotransmitter uptake and degradation especially glutamate and GABA

Question 14

Other passive support functions of astrocytes

Answer 14

• K+ homeostasis (remove excess K+)
• neuronal energy supply
• maintenance of BBB
• injury response and recovery

Question 15

Active functions of astrocytes

Answer 15

• Modulation of neuronal function (via Ca2+)

- Modulation of blood flow

Question 16

What is caused by inhibition of glial glutamate transporters?

Answer 16

cells are more depolarized, extended depolarisation can cause cell death

Question 17

How are glia excited?

Answer 17

Ca2+

Question 18

Causes of glial excitement

Answer 18

-neurotransmitters such
as ATP, glutamate
-Trauma
-Spontaneous
-Inflammatory mediators

Question 19

Mechanism of glia commuication

Answer 19

Glial cells contain synaptic vesicles and show exocytosis.

Question 20

regulation of neuronal function by astrocytes

Answer 20

• Neurons are inhibited by calcium wave (hyperpolarised)

- Mechanism involves release of ATP from glia which causes Ca2+

Question 21

How do Astrocytes regulate vascular tone?

Answer 21

Calcium wave initiated within an astrocyte causes vasoconstriction or vasodilation.

Question 22

Difference between oligodendrocytes and schwann cells

Answer 22

Schwann is in the PNS, Oligodendrocyte is CNS and schwann only does one axon compared to many

Question 23

Microglia

Answer 23

• local defence cells from bone marrow
• 5-20% of cells in mouse brain
• Resemble macrophages – phagocytic

Question 24

Role of microglia

Answer 24

-Constantly survey the CNS. (function in normal healthy tissue)
-Change rapidly in response to inflammation or
injury- upregulate cytokines/growth factors

Question 25

Structure of peripheral nerves

Answer 25

-One or more bundles (fascicles) or nerve fibres with epineurium, endoneurium and perineurium

Question 26

perineurium

Answer 26

collagenous tissue that surrounds fascicles of nerve fibres

Question 27

epineurium

Answer 27

If there is more than one fascicle, than there is further layer of collagenous tissue

Question 28

endoneurium

Answer 28

Within each fascicles, each nerve fibre and Schwann cell is surrounded by loose vascular supporting tissue called endoneurium