Blood Brain Barrier Flashcards
ECF accounts for how much of the brain volume?
15%
Increase in what during synaptic activity?
Glutamate, and k+ causing depolarisation.
CSF synthesised by what?
Choroid plexus.
what is the choroid plexus made of?
specialised glial cells
What does the BBB protect the ecf from?
fluctuations in blood composition and limits the entry of compounds in ecf.
what is the function of the csf?
provide an appropriate local environment for neurons and glia by maintaining appropriate concs. of salt.
what is the median of exchange between the brain ecf and systemic blood?
csf
what is the main waster product removed by the csf?
lactate
forms thin layer around brain and spinal cord in what space?
sub arachnoid space
what connects the right and left lateral ventricles to the 3rd ventricle?
foramina of monroe.
what does the cerebral aquaduct connect?
3rd and 4th ventricle.
formaina of lushka allows what?
csf into subarachnoid space in brain
what allows csf down into spinal cord?
foramina of majendee.
what are the two ways csf is made?
ultra-filtration of plasma across the fenestrated capillary wall into ecf beneath the basolateral membrane of choroid epithelial cell.
choriod epithelial cells secrete fluid into the ventricles.
what is the basolateral side important for?
neutralising acids produced by cns cells
what important pump is in the apical membrane?
Na+-K+ ATPase pump, responsible for the Na+ efflux into the CSF.
what is the net effect of secretion?
increased Na+ outside the cell drags Na+ from the other side.
where does absorption of csf occur?
arachnoid villi within the subarachnoid space.
how does absorption of csf occur?
a) bulk flow via arachnoid villi 500 mls/day
b) diffusion
c) active transport
what is the function of arachnoid granulations?
small protrusions of arachnoid through the dura mata, protrude into venous sinuses and allow the csf to exit subarachnoid space and enter the blood stream.
what is a virchow robin space?
immunological space between the pia and capillary. expanded by leucocytes - space is formed when large vessel takes pia with them diving into the brain - fills with leucocytes, found in pts with viral encephalitis.
what is different about the capillary endothelium cells of the brain capillaries?
they have tight junctions and not fenestrations. limits access to larger molecules.
if lipid solubility is increased then is there more or less of a chance of it accessing the brain?
more
what are organs called not covered by the BBB?
Circumventricular organs - tight junctions replaced by normal fenestrated endothelia.
What are the 4 organs in the brain?
posterior pituitary, median eminence, area postrema, OVLT(Organum vasculosum laminae terminalis).
