Neurons and Astrocytes

Question 1

What determines whether a neuron is peripheral or central?

Answer 1

Location of their cell body - peripheral neurons have their cell bodies outside of the CNS, whereas central neurons have their cell bodies within the CNS

Question 2

Name a class of peripheral neurons which extends into the CNS

Answer 2

Dorsal root ganglion sensory neurons

Question 3

Describe the contents of a neuronal cell body

Answer 3

A neuronal cell body contains a large nucleus, prominent nucleolus, abundant rough ER, well-developed Golgi apparatus, abundant mitochondria, and a highly organised cytoskeleton

Question 4

Describe four types of neuron morphology

Answer 4

Unipolar, bipolar, pseudounipolar, and multipolar

Question 5

What is the most common neuron morphology?

Answer 5

Multipolar

Question 6

Name two types of bipolar neurons

Answer 6

Retinal neurons and olfactory neurons

Question 7

Name two types of multipolar neurons and their location

Answer 7

Pyramidal neurons in the hippocampus and Purkinje cells in the cerebellum

Question 8

What morphology do pain sensory neurons typically have?

Answer 8

Unipolar

Question 9

Name five organisational mechanosms for neuron circuits

Answer 9

Divergence, convergence, serial processing, parallel processing, and reverberation

Question 10

What are the three main neuronal compartments?

Answer 10

Dendrites, axons, and synapses

Question 11

State the contents of the axon compartment

Answer 11

Axon hillock, myelin sheath, nodes of Ranvier, paranode, and juxtaparanode

Question 12

Name specific components of the somatodendritic compartment

Answer 12

Microtubule stabilising protein MAP2B, all neurotransmitter receptors, postsynaptic density scaffolding, and signalling proteins for the post-synapse

Question 13

What part of a neuron receives the majority of synapses?

Answer 13

Dendritic spines

Question 14

Name four shapes dendritic spines can take

Answer 14

Stubby, thin, mushroom, filopodium

Question 15

What is the function of tau in the axon?

Answer 15

It is a microtubule stabilising protein (MAP)

Question 16

Name three components required at the pre-synapse

Answer 16

Neurotransmitters, growth factor receptors, and SNARE complexes

Question 17

Name two forms of synaptic terminal

Answer 17

Boutons and varicosities

Question 18

Name three places a neuron can synapse

Answer 18

With another neuron, a muscle cell, or a gland

Question 19

How is vesicle fusion triggered at the synapse?

Answer 19

Depolarisation causes a calcium ion influx at the terminal, leading to vesicle fusion via molecular binding complexes

Question 20

Are axo-somatic and axo-axonic synapses usually excitatory or inhibitory?

Answer 20

Inhibitory

Question 21

Are axo-dendritic synapses usually excitatory or inhibitory?

Answer 21

Excitatory

Question 22

Name two excitatory neurotransmitters

Answer 22

Glutamate and acetylcholine

Question 23

Name two inhibitory neurotransmitters

Answer 23

GABA and dopamine

Question 24

How many glutamate receptor proteins are there?

Answer 24

11

Question 25

What percentage of brain cells is made up by astrocytes?

Answer 25

40%

Question 26

Name three components of the cytoskeleton of astrocytes

Answer 26

Glial fibrillary acidic protein (GFAP), microtubules, actin

Question 27

State a metabolic function of astrocytes

Answer 27

Cholesterol production, providing lactate to neurons, synthesis of apolipoprotein E

Question 28

State how astrocytic dysfunction can impact on neurodegeneration

Answer 28

It can increase glutamate cytotoxicity, increase levels of calcium and ATP release, increase nitric oxide production, cause accumulation of superoxide dismutase, and form glial scars

Question 29

How do astrocytes contribute to the blood brain barrier?

Answer 29

The blood brain barrier is formed by the tight association of brain capillary endothelial cells. Astrocytic endfeet enwrap endothelial cells, providing a gateway for nutrients to enter and metabolites to leave the CNS

Question 30

Give 5 functions of astrocyte-expressed aquaporin 4

Answer 30

Potassium buffering, CSF circulation, interstitial fluid resorption, metabolic waste clearance, neuroinflammation, osmosensation, cell migration, calcium ion signalling, regulation of the volume of extracellular space

Question 31

How can astrocytes modulate neuronal function at the synapse?

Answer 31

By removing and releasing neurotransmitters

Question 32

How do astrocytes help to recycle GABA?

Answer 32

They endocytose unbound GABA, convert it to glutamate and then glutamine, and re-supply it to the neuron

Question 33

Why do astrocytes act as a potassium reservoir?

Answer 33

For neurons to function, extracellular potassium concentration must be kept low

Question 34

Astrocytes help to spatially buffer potassium via gap junctions. Which other cell type contributes to this process?

Answer 34

Oligodendrocytes

Question 35

True or false: astrocytes are the only brain cells that store glycogen

Answer 35

True

Question 36

Give two examples of radial glia

Answer 36

Bergmann glia in the cerebellum, and Muller cells in the retina