Glia Flashcards
What do glia do ?
support the network of neurones . Nourish, insulate and remove waste products
What do astrocytes do?
the most abundant glia : Structural support Nutrition Remove neurotransmitters maintain ionic environment help form BBB
What provides immune response in neurones ?
Microglia
What are oligodendrocytes ?
provide insulation to neurones
How do astrocytes provide energy for neurones ?
neurones cant store/produce glycogen
Astrocytes produce and shuttle it with glucose to the neurone
How do astrocytes interact with neurotransmitters?
help keep ExCellular conc of neurotransmitters (glutamate) low via intake from transmitters
What do astrocytes help maintain in terms of ions levels?
buffer the conc of K+ . k+ increased in high neuronal activity and astrocytes take in K+.
What myelinates neurones in the CNS? what about the PNS?
CNS = Oligodendrocytes PNS = Schwann
How do microglia cells work?
recognise foreign material , expand and phagocytose
what are the 2 functions of the BBB?
Limit diffusion from blood to brain ECF
Maintain environment of neurones
What 3 functions do brain capillaries have ?
Tight junctions between endothelial cells
basement membrane surrounding capillary
end feet of astrocyte processes
What is transported across the BBB?
Glucose, amino acids and potassium
How is the CNS immune privileged ?
Rigid skull = not much volume increase
does not undergo rapid rejection of allografts
Microglia = antigen presenting cells
T cells can enter the CNS but inhibits the inflammatory T-cell response
What are the 4 main sections of the neurone ?
Cell soma (body)
Dendrites
Axon
Terminals (Pre/postsynaptic)
how is neurotransmitter released ?
Depolarisation in terminal = opening of VGCC . Ca2+ entry making vesicles fuse and release transmitter
diffuse across synaptic cleft and bind to receptor in postsynaptic membrane
what are the 3 types of neurotransmitters and name an example of each type.
Amino acid = Glutamate, GABA, glycine
Biogenic amino = ACh , NA, Dopamine, serotonin and histamine
Peptides = CCK, Somatostatin
what are the excitatory and inhibitory amino acid neurotransmitters ?
Excitatory = Glutamate Inhibitory = Glycine , GABA
What are the ionotropic glutamate receptors and what do they do?
AMPA - Na+/K+
Kainate - Na+/k+
NMDA - Na/k/Ca
allow the following ions to be permeable which depolarises = increases excitabilty
What do glutamatergic Metabotropic receptors do?
G- coupled protein receptor-
IP3 and Ca2+ increase
inhibition of adenylate cyclase = decrease cAMP
What do excitatory neurotransmitters do ?
depolarisation = EPSP leads to more APs
What do AMPA receptors do ?
Initiate the fast depolarisation fro influx of Na+ when glutamate attaches . Allow NMDA receptors to activate
What do NMDA receptors do and how are they activated?
NDMA activation requires Glutamate and depolarised post synaptic neurone
Allow Ca2+ entry and causes induction of LTP = important role in learning and memory
How can AMPA receptors be affected from NDMA receptors ?
AMPS can up regulate when there is high activation of NMDA receptors
What happens when too glutamate is produced?
Too much Ca2+ entry via NMDA so leads to excitotoxity
What is the difference between GABA and glycine ?
GABA inhibits in brain
Glycine in brainstem and spinal cord
How do GABAa and glycine receptors work?
Integrated Cl- ion channels open when bounded by neurotransmitter . Influx of Cl- = IPSP = decreased APs
What drugs bind to GABA receptors and enhance the response ?
Barbiturates
Benzodiazepines
What does glycine do in the spinal cord and brainstem ?
released by inhibitory interneurones to slow down APs
Where is ACh used ?
ANS e.g. postganglinoic parasympathetic
Central brain - nictoninc and mus receptors
enhance release of other neurotransmitters
Where in the brain is ACh used?
originates from basal forebrain / brainstem
diffuse projections to cortex
local interneurones in CStr
What does ACh do in the brain?
What is a common condition of ACh neurone degeneration ?
arousal, learning , memory and motor control
degeneration = Alzheimer’s
Cholinesterase inhibitors used to alleviate symptoms
What are the 3 dopaminergic pathways ?
Nigrostriatal pathway = Motor control
Mesolimbic = mood , arousal and reward
Mesocortical = same as above
what is a theory for the pathology of schizophrenia ?
Dopamine release too high , seen in amphetamine users
What does Carbidopa do ?
Inhibits AADC so L-DOPA is not converted to Dopamine
How is dopamine transported to brain?
past BBB via LNAA and converted to dopamine from L-DOPA via AADC
how do NA pathways in the CNS work?
Cell bodies in brainstem (Locus Cerlus) and there is diffuse release to cortex, hypothalamus and cerebellum
What does NA do in CNS?
increase hood and state of arousal - amphetamines release NA and dopamine
What do serotonergic pathways in the CNS do? What are SSRIs used for?
increase mood/ sleep
depression and anxiety
