session 2: Cellular physiology of the brain Flashcards
what r the Components of the CNS?
Network of neurones with supporting glia
what r the types of glial cells (neuroglia) ?
- Astrocytes
- Oligodendrocytes
- Microglia
- Ependymal cells
role of astrocytes ? (5)
how do neurones get their energy? which glia is responsible for this?
astrocytes can store glucose as glycogen and then break it down into pyruvate–>lactate
lactate moves into interstitial space>>into neurons
in neurons, converted to pyruvate> broken down to form ATP to supply neuron with energy
THIS STORE in ASTROCYTE IS LIMITED!
it will only keep neurons supplied with lacatte for 10-15 mins!
how is the neurotransmitter Glutamate removed from neuron terminal? why should it be removed?
glutamate is then broken down into Glutamine then can be transferred back into Glutamate to be taken back into the presynaptic terminal
describe the Astrocyte mechanism of taking up K+ in the brain? why is this important?
increased K+ causes depolarization and may lead to epilepsy
astrocytes have a very negative resting membrane potential
movement if K+ via
- channels
- Na-K-2Cl- transporter
- Na-K+ atpase
role of Oligodendrocytes
role of Microglia
- Immunocompetent cells
- Recognise foreign material - activated
- Phagocytosis to remove debris and foreign material
• Brain’s main defence system, acts as APC to t cells
why do we have a BBB? explain its strucutre
Limits diffusion of substances from the blood to the brain’s ECF, bc blood does not make a good environment in the brain.
what sort of things r transported across the BBB? which GLucose transporter is in the brain?
draw the typical neuronal structure
explain Neurotransmitter release: The synapse
types of Neurotransmitters in the CNS
over 70% of the all CNS synapses are _________
glutamatergic
what is the major excitatory neurotransmitter? inhibitory aa neurotrasmitter?
– mainly glutamate
– GABA
– Glycine
what r the main Ionotropic ligand gated recepters?
AMPA>> Na+/K+
NMDA>> receptors Na+/K+ & Ca2+
function of NMDA receptor, how does it work?
blocked by Mg+
permeable to Ca2+
NMDA receptors need glutamate to bind and the cell to be depolarised to allow ion flow through the channel
– Also glycine acts as a co-agonist
what is important for induction of LTP?
Ca2+ entry through NMDA receptors
(nadia likes milk)
which drugs enhance the response to GABA?
what r their effects?
– Barbiturates - anxiolytic and sedative actions, but not used for this now
- risk of fatal overdose also dependence and tolerance
- BUT sometimes used as anti-epileptic drugs
– Benzodiazepines
have sedative and anxiolytic effects
used to treat anxiety, insomnia and epilepsy
where is glycine released in the knee relfex?
Inhibitory interneurones in the spinal cord release glycine
function of nucleus basalis?
aslo known as ‘nucleus basalis of meynert”
is a group of neurons in the substantia innominata of the basal forebrain which has wide projections to the neocortex and is rich in Ach and choline acetyltransferase
Involved in arousal, learning & memory, motor control
what r the Dopaminergic pathways in the CNS?
MNM make me happy and dope
- Nigrostriatal >> involved in motor control
- Mesocortical/mesolimbic pathway >> involved in mood, arousal and reward
which areas in the brain r rich in dopamine
Dopamine therapy
L-dopa can pass pass through the BBB and be converted to dopamine by AADC.
this AADC is also present in the periphery, but u dont want too much dopamine being made in the periphery so we give carbidopa which cant cross the BBB
increased levels of dopamine in the periphery can cause side effect, what r they, and how do we prevent this?
Gi side effects, we give CARBIDOPA that inhibits AADC
what level of the brain is this? arrow?
if u see mickey mouse>> 3ala 6ool think MIDBRAIN!
mickey mouse’s eyebrows>> Substania Nigra
