Neurons and Glial Cells

Question 1

where does the axon arise from

Answer 1

axon hillock

Question 2

what is the axoplasm and what does it lack

Answer 2

axonal cytoplasm
lacks RER and Golgi

Question 3

why must materials be transported back and forth between the cell body and terminus

Answer 3

lacks components for synthesising new proteins and degrading old ones

Question 4

fast component of axonal transport

Answer 4

50 - 400 mm/day
transports cytoplasmic proteins and macromolecules

Question 5

slow component of axonal transport

Answer 5

1 - 4 mm/day
transports cytoskeletal components

Question 6

number of glial cells vs neurons

Answer 6

10x more

Question 7

Anterograde transport
Retrograde transport

Answer 7

Anterograde transport is forward, away from cell body
Retrograde transport is transport towards the cell body

Question 8

contents of dendrites

Answer 8

all cytoplasmic components found in the cell body except the Golgi apparatus

Question 9

function of dendritic spines

Answer 9

increase surface area

Question 10

pre-synaptic membrane

Answer 10

thickened region in the plasmalemma
contains voltage-gated Ca2+ channels

Question 11

arrival of an action potential at an axon terminal

Answer 11

opening of Ca2+ channels
triggers exocytosis of the neurotransmitters

Question 12

synaptic cleft size

Answer 12

20 - 40 mm

Question 13

postsynaptic membrane

Answer 13

thickened region in the plasmalemma
excitatory synapses contains voltage-gated Na+ channels
inhibitory synapses contains voltage-gated K+ or Cl- channels

Question 14

what generally results from damage to the cell body of a neuron
why

Answer 14

cell death
cannot undergo cell division

Question 15

what is the initial result of severing or crushing of an axon

Answer 15

cell body swells and nucleus is displaced peripherally
chromatolysis

Question 16

chromatolysis

Answer 16

after axonal damage, Nissl bodies disperse with a concomitant loss in the cytoplasmic basophilia

Question 17

Wallerian degeneration

Answer 17

anterograde degeneration after from the site of injury
Axon swells and degenerates causing fragmentation of myelin sheath which are removed b phagocytes

Question 18

schwann cells in axonal damage

Answer 18

can proliferate and form a tube distal to the injury
causes axon to regain function
takes 3 weeks

Question 19

lesion in peripheral neuron

Question 20

axonal sprouts

Question 21

axon stump

Question 22

oligodendrocytes overview

Answer 22

60 - 80% of glial cells
myelin sheath formation

Question 23

astrocyte overview

Answer 23

25% of glial cells
BBB
structural support and scar formation
secretion of growth factors
water transport
excess transport -> cerebral oedema

Question 24

microglia overview

Answer 24

5-10% of glia cells
brain macrophages
secretion of inflammatory cytokines and chemokines
APCs

Question 25

astrocyte pedicles

Answer 25

end feet that terminate on capillaries/pia matter

Question 26

fibrous astrocytes

Answer 26

located primarily in white matter long spindly processes with few branches

Question 27

protoplasmic astrocytes

Answer 27

located in grey matter thick, lightly branched processes closely apposed to neuron somas

Question 28

functions of astrocytes

Answer 28

regulation of intercellular environment structural support metabolise neurotransmitters mediate exchange of nutrients and metabolites between blood and neurons form glial scar after CNS injury

Question 29

tripartite synapse

Question 30

oligodendrocytes in white and grey matter

Answer 30

white matter: predominant glial cell, produce myelin sheath grey matter: closely associated with cell bodies functioning as satellite cells and anchor cell bodies

Question 31

what is the PNS composed of

Answer 31

neuron processes of CNS neurons and PSN neural cells Schwann cells and satellite cells nerve endings

Question 32

peripheral nerve structure

Answer 32

fascicles of nerve fibres surrounded by myelin sheaths and connective tissue epineurium, perineurium and endoneurium

Question 33

epineurium

Answer 33

connective tissue surrounding entire nerve

Question 34

perineurium

Answer 34

layer of dense connective tissue around each fascicle

Question 35

endoneurium

Answer 35

thin reticular layer surrounding each individual nerve fibre contains Schwann cells lies outside and encloses the myelin sheath

Question 36

number of axons myelinated by ODGs vs Schwann cells

Answer 36

ODGs myelinate portions of several axons Schwann cells myelinate portions of a single axon

Question 37

ganglia what do they contain

Answer 37

encapsulated collections of neuron cell bodies located outside CNS contain satellite cells, connective tissue elements and neurons

Question 38

ganglia satellite cells

Answer 38

amphicytes glial cells that form a capsule of cells around neural cell bodies