Flashcards in Glia & Neurones Deck (17):
Give some examples of glial cells
Astrocytes, oligodendrocytes, microglia
What are the roles of astrocytes?
Nourish neurones, remove neurotransmitters, maintain ionic environment and help to form blood brain barrier
How do astrocytes help provide energy for neurones?
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
How do astrocytes help to remove neurotransmitters?
They have transporters for transmitters such as glutamate which helps to keep the extracellular concentration low
How do astrocytes hel to buffer K+ in brain ECF?
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
What do oligodendrocytes to?
Myelinate axons in CNS
How do oligodendrocytes and schwann cells differ?
Oligodendrocytes = CNS, myelinate multiple axons
Schwann cells = PNS, can myelinate only one axon
What do microglia do?
Immunocompetent cells - become activate when they recognise foreign material and phagocytose
How is the blood brain barrier formed?
Tight junctions between endothelial cells, basement membrane surrounding capillary, end feet of astrocyte processes
Describe how neurotransmitters are released
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
Give some examples of amino acid neurotransmitters
Glutamate, GABA, glycine
Give some examples of biogenic amine neurotransmitters
Acetylcholine, dopamine, serotonin, noradrenalin
What is the main excitatory neurotransmitter?
What is the main inhibitory neurotransmitter?
What are AMPA receptors permeable to?
What are NMDA receptors permeable to?
Na/K+ and Ca2+