Glia & Neurones

Question 1

Give some examples of glial cells

Answer 1

Astrocytes, oligodendrocytes, microglia

Question 2

What are the roles of astrocytes?

Answer 2

Nourish neurones, remove neurotransmitters, maintain ionic environment and help to form blood brain barrier

Question 3

How do astrocytes help provide energy for neurones?

Answer 3

Glucose-lactate shuttle

Astrocytes take up glucose from the blood, convert it to lactate, release it and thus provide an energy substrate to neurons

Astrocytes are the only cells in the brain which can synthesise glycogen and thus can serve as an energy reservoir

Question 4

How do astrocytes help to remove neurotransmitters?

Answer 4

They have transporters for transmitters such as glutamate which helps to keep the extracellular concentration low

Question 5

How do astrocytes hel to buffer K+ in brain ECF?

Answer 5

Express high density of K+ channels

When neurons are active, they release K+ increasing the local extracellular concentration. Because astrocytes are highly permeable to potassium, they rapidly clear the excess accumulation in the extracellular space

Question 6

What do oligodendrocytes to?

Answer 6

Myelinate axons in CNS

Question 7

How do oligodendrocytes and schwann cells differ?

Answer 7

Oligodendrocytes = CNS, myelinate multiple axons

Schwann cells = PNS, can myelinate only one axon

Question 8

What do microglia do?

Answer 8

Immunocompetent cells - become activate when they recognise foreign material and phagocytose

Question 9

How is the blood brain barrier formed?

Answer 9

Tight junctions between endothelial cells, basement membrane surrounding capillary, end feet of astrocyte processes

Question 10

Describe how neurotransmitters are released

Answer 10

Depolarisation in the presynaptic terminal opens voltage gated Ca2+ channels - Ca2+ enters terminal

Vesicles fuse and release transmitter

Neurotransmitter diffuses across synaptic cleft and binds to receptors on postsynaptic membrane

Question 11

Give some examples of amino acid neurotransmitters

Answer 11

Glutamate, GABA, glycine

Question 12

Give some examples of biogenic amine neurotransmitters

Answer 12

Acetylcholine, dopamine, serotonin, noradrenalin

Question 13

What is the main excitatory neurotransmitter?

Answer 13

Glutamate

Question 14

What is the main inhibitory neurotransmitter?

Answer 14

GABA

Question 15

What are AMPA receptors permeable to?

Answer 15

Na+/K+

Question 16

What are NMDA receptors permeable to?

Answer 16

Na/K+ and Ca2+

Question 17

What do excitatory neurotransmitters cause?

Answer 17

Depolarisation of the postsynaptic cell by acting on ligand gated ion channels

Depolarisation causes more AP, increasing firing of neurons