Lecture 3-Neurones And Glia Flashcards
What are the types of glial cells?
- astrocytes
- oligodendrocytes
- microglia
What are the roles of astrocytes?
- structural support
- provide nutrition for neurones
- remove neurotransmitters
- maintain ionic environment
- help to form blood brain barrier
How do astrocytes provide nutrition for neurones?
Glucose-lactose shuttle: produce lactate which can be transferred to neurones
How do astrocytes help to remove neurotransmitters?
Re-uptake: transporters for transmitters such as glutamate
Why don’t we want glutamate spreading to other synapses?
Too much glutamate is toxic to neurones
Why do astrocytes need to buffer K+ in brain ECF?
Too much K+ -> depolarisation -> inappropriate AP firing in neurones -> epilepsy
What do oligodendrocytes do?
Myelinate axons in CNS
What is the equivalent of oligodendrocytes in the PNS?
Schwann cells
What are microglia?
Immunocompetent cells, recognise foreign cells -> phagocytosis
Why is a blood brain barrier needed?
Maintains optimal environment for neurones
What do brain capillaries have?
- tight junctions between endothelial cells
- basement membrane
- end feet of astrocyte processes
What are the three groups of neurotransmitters?
- amino acid: glutamate, GABA, glycine
- biogenic amines: ACh, NA, dopamine, serotonin, histamine
- peptides: somatostatin, CCK, neuropeptide Y
What is the major excitatory AA neurotransmitter?
Glutamate
Which AA neurotransmitters are inhibitory?
GABA and glycine
What are the two types of glutamate receptors?
- ionotropic
- metabotropic
What are ionotropic glutamate receptors?
Ligand-gated ion channels: AMPA, Kainate and NMDA receptors
Permeable to Na, K and sometimes Ca
What are metabotropic glutamate receptors?
GPCRs
Linked to either changes in IP3 and Ca2+ mobilisation or inhibition of adenylate cyclase and decreased cAMP levels
Describe the fast excitatory response
Depolarisation of postsynaptic cell by acting on ligand-gated ion channels - excitatory post-synaptic potential (EPSP), depolarisation -> more AP
What is the difference between AMPA and NMDA receptors?
- AMPA: mediate initial fast depolarisation
- NMDA: permeable to Ca2+, need glutamate to bind and cell to be depolarised to allow ion flow through channel
True or false: NMDA receptors become activated and down-regulate AMPA receptors
FALSE - up-regulate AMPA
What causes long term potentiation (LTP)?
Strong, high frequency stimulation
Why is too much Ca2+ entry through NMDA receptors dangerous?
Causes excitotoxicity
Where is glycine mostly found?
Brainstem and spinal cord
What are GABA and glycine receptors and how do they lead to inhibitory post-synaptic potential (IPSP)?
Cl- channels
Opening of the channels -> hyperpolarisation -> IPSP
