Neurone cells

Question 1

What classes can neural cells be split into?

Answer 1

neurons
differentiated glia
- ogliodendrocytes
- microglia
- astrocytes
other glial cells

Question 2

Where are inputs into neurones?

Answer 2

dendrites

Question 3

Where are action potentials propogated from?

Answer 3

axon hillock, then down the axon

Question 4

What are the 2 types of synapses?

Answer 4

chemical - use neurotransmitters, bind to receptors

electrical - much less - channels that allow direct flow of current -

Question 4

Cell make up at synapses?

Answer 4

MANY proteins for receptors - electron dense material on TEM
mitochondria for energy to pass neurotransmittors

Question 4

Why are electrical synapses important?

Answer 4

important for synchronised electrical activity

Question 5

How does chemical synaptic transmission work?

Answer 5

axon potential depolarises synaptic terminal membraneS

Question 6

Structure of electrical synapses

Answer 6

lots of electron dense material - gap junctions - continuous channel allows transmission of ions and currents

Question 7

Where are most excitatory sysnapses?

Answer 7

often concentrated on dendritic spines

Question 8

What is neural plasticity?

Answer 8

changes in neronal/synaptic structure ans function in respinse to neural activity

spines are dynamic structures - number, size, composition
spine remodelling linked to neural activity

Question 9

What are betz cells? (upper motor neurones)

Answer 9

upper motor neurons - large excitatory (glutamatergic)
long projectiions, pyramidal cells
vulnerable in motor neurone disease

Question 10

What are medium spiny neurones?

Answer 10

striatal interneurons
small, inhibitory, (GABAeric)
vulnerable in huntigtons disease

Question 11

What are ogliodendrocytes?

Answer 11

myelinating cells of the CNS
enables rapid nerve conduction
Myelin sheath interrupted by nodes of Ranvier

they also provide metabolic support for the axons (lactate transporters)

Question 12

What is saltatory conduction?

Answer 12

propogation of an impulse across nodes of Ranvier due to myelination

Question 13

How is the myelin sheath formed?

Answer 13

ogliodendrocyte processes wrap around axons
Highly compacted - 70% lipid, 30% protein
Myelin specific proteins and be used as markers - very specialised proteins

Question 14

Microglia?

Answer 14

originate from different palce embryologically
resting state is highly ramified, motile processes survey environment
on activationm retract processes, become amoeboid and motile
are prolifereative

Question 15

What are the functions of microglia?

Answer 15

immune surveillance
phagocytosis - debris, microbes
synaptic plasticity - pruning of spines
‘bad’ and ‘good’ microglia - some more antiinflammatory

Question 16

What are astrocytes?

Answer 16

‘star-like’ cells
most numerous glial cells in CNS (similar numbers to neurons)
highly heterogeneous -morphology is variable - not all star shaped
contribute to blood brain barrier

Question 17

How do astrocytes contribute to the blood brain barrier?

Answer 17

processes of the astrocytes wrap around of the capillaries
express proteins for specialised water channels

Question 18

Functions of astrocytes?

Answer 18

structurally they define the brain mico-architecture
metabolic support - e.g. Glutamate-Glutamine shuttle
neurovascular coupling - changes in cerebral blood flow (vasodilation+) in response to neural activity
envelop synapses - buffer K+, glutamate etc
Proliferate during disease
important in scarring of CNS

Question 19

Other specialised glia?

Answer 19

radial cells - important for brain development
bergmann glia in cerebellum
Muller cells - scaffold for other cells to form in the retina

Question 20

Brief description of motor neurone disease?

Answer 20

Loss of motor neurons in upper cortex and lower spinal cord - pathological changes in all neural cell types though

Question 21

Brief description of MS?

Answer 21

Damaged ogliodendrocytes - are attacked - this is where the primary pathology is
acute symptoms relfect dysfunction of the neurons

Question 22

Where are axons gathered? in cns
Where is PNS?

Answer 22

tracts

bundled into nerves

Question 23

What are tracts that cross the midline called?

Answer 23

tracts are gathered axons
commissures

Question 24

What id the difference in myelination between CNS and PNS?

Answer 24

ogliodendrocytes in brains and spinal cord

schwann cells in peripheral

Question 25

How is the blood brain barrier formed?

Answer 25

endothelial cell tight junctions
basement membrane (few fenestrations)
astrocyte end feet
pericytes

Question 26

What are ependymal cells?

Answer 26

line ventricles and central canal of the spinal cord

involved in CSF production, flow and absorption

ciliated to facilitate flow

allow solute exchange between nervous tissue and \CSF