Neurones

Question 1

How do neurones communicate?

Answer 1

Via synapses

Question 2

How many types of synapses are there?

Answer 2

2

Question 3

What are the two types of synapses?

Answer 3

Chemical
Electrical

Question 4

How do neurones communicate by a chemical synapse?

Answer 4

Via neurotransmitters

Question 5

How do neurones communicate by a electrical synapse?

Answer 5

Via direct flow of ions

Question 6

Which type of synapse happens more frequently?

Answer 6

Chemical

Question 7

What happens during a chemical synaptic

Answer 7

• Axon potential depolarises synaptic terminal membrane
• Opening of voltage-gated calcium channels leads to calcium influx
• Calcium influx triggers neurotransmitter release

Question 8

What is neural plasticity?

Answer 8

Changes in neuronal/synaptic structure and function in response to neural activity

Question 9

What do neurons differ in?

Answer 9

Size
Morphology
Neurotransmitter content
Electrical properties

Question 10

What are oligodendrocytes?

Answer 10

Myelinating cells of the CNS

Question 11

What are oligodendrocytes unique to?

Answer 11

Vertebraes

Question 12

What is the main function of myelin?

Answer 12

Insulates axon segments, enabling rapid nerve conduction

Question 13

What are myelin sheath segments interrupted by?

Answer 13

Nodes of Ranvier – where ion channels are concentration, this allows saltatory conduction

Question 14

What are oligodendrocytes important for?

Answer 14

They provide metabolic support for axons

Question 15

What are microglia?

Answer 15

Resident immune cells of the CNS

Question 16

Where do microglia originate from?

Answer 16

Originate from yolk sac progenitors that migrate into CNS during embryonic development

Question 17

Describe microglia in ‘resting state’

Answer 17

Highly ramified

Question 18

What are the functions of microglia?

Answer 18

Immune surveillance
Phagocytosis – debris/microbes
Synaptic plasticity – pruning of spines
“Good” (M2) & “bad” (M1) microglia

Question 19

What are the most numerous glial cells in the CNS?

Answer 19

Astrocytes

Question 20

What are the functions of astrocytes?

Answer 20

Structural - define brain micro-architecture
Envelope synapses
Metabolic support
Neurovascular coupling – changes in cerebral blood flow in response to neural activity
Proliferate in disease = gliosis or astrocytosis

Question 21

What are the types of specialised astrocytes?

Answer 21

Radial glia
Bergmann glia
Muller cells

Question 22

What are radial glia important for?

Answer 22

Brain development

Question 23

Where are bergmann glia located?

Answer 23

Cerebellum

Question 24

Where are muller cells located?

Answer 24

Retina

Question 25

What is motor neurone disease?

Answer 25

Adult onset neurodegenerative disease characterised by loss of upper (motor cortex) and lower (spinal cord) motor neurones

Question 26

What is multiple sclerosis?

Answer 26

Autoimmune demyelinating disease where immune cells attack the myelin sheath of oligodendrocytes

Question 27

What are axons in the CNS gathered into?

Answer 27

Tracts

Question 28

What is grey matter abundant in?

Answer 28

Abundant in neural cell bodies & processes

Question 29

What does white matter contain?

Answer 29

Contains abundance of myelinated tracts & commissures

Question 30

What are axons in the PNS bundles into?

Answer 30

Nerves

Question 31

What is the blood-brain barrier formed by?

Answer 31

Endothelial cell tight junctions Basement membrane (few fenestrations) Astrocyte end feet Pericytes (contractile, aid blood flow)

Question 32

What is the blood-brain barrier sensitive to?

Answer 32

Inflammation Hypertension Trauma Ischaemia

Question 33

What are the functions of ependymal cells?

Answer 33

CSF production Flow & absorption

Question 34

What do ependymal cells allow?

Answer 34

Allow solute exchange between nervous tissue & CSF

Question 35

What is the choroid plexus?

Answer 35

Frond-like projections in ventricles

Question 36

What is the choroid plexus formed from?

Answer 36

Modified ependymal cells - villi form around network of capillaries → highly vascularised with a large surface area

Question 37

What is the choroid plexus the main site for?

Answer 37

CSF production by plasma filtration driven by solute secretion