NBSS: (neuroscience) blood-CNS barriers, homeostasis and regulation Flashcards
describe E. goldmanns first and second experiments
therefore based off where they were injected, goldman hypthesised that there must be a barrier of some sort between blood and CNS
in the 1960s using electron microscopy and molecular tracers such as horseradish peroxidase, what was proved to be the barrier between the blood and CNS?
brain capillaries
how many arteries supply the brain with blood?
4
what are the 2 types of arteries that supply the brain with blood
2 carotid arteries, 2 vertebral arteries
where do the carotid and vertebral arteries merge?
circle of willis at the base of the brain
what emerges off of the circle of willis
plial arteries
what 4 vessels do plial arteries subdivide into
penetrating arteries
penetrating arterioles
intracerebral arterioles
capillaries
what are 2 key characteristics of brain capillary network
- complexity
- high density of vessels
what is the capillary wall of brain capillary cell formed of
a SINGLE endothelial cell joined by tight and adherent junctions at the paracellular cleft
what other components make up the neurovascular unit other than the brain capillary endothelial cells
microglia
oligodendrocytes
astrocytes
pericytes
basement membrane
glycocalyx
what is a key component of astrocytes
glial fabrillary acidic protein
how do astrocytes communicate with eachother
via end feet
what are 2 key parts of astrocytes
perivascular sheet
glia-limitans (end feet)
functions of astrocytes
whats the difference in permeation across blood brain barrier in:
simple diffusion
passive diffusion
transporters influx
transporters efflux
endocytosis
in cerebral capillaries, the paracellular movement of molecules is restricted by what
intracellular junction complexes
what is the intracellular junction complex composed of
adherens junctions
tight junctions
what is the difference in restriction between adherens junctions
tight junctions
adherens = NON restrictive
tight = RESTRICTIVE
what are the 3 functions of the cerebral capillary endothelium
- PHYSICAL BARRIER - continuous strand of tight junctions
- TRANSPORT/ SELECTIVE BARRIER - high level of transporters, reduced number of vesicles
- METABOLIC BARRIERS - enzyme systems
describe the lipophicility of heroin and its subsequent effects when taken
which molecule has a greater ability to cross the blood brain barrier than you’d predict
D glucose
what are 2 types of SLC transporters
- facilitated diffusion transporters
- secondary active transporters
what is the structure of p-glycoprotein
2 repeating units
joined by linka group
12 transmembrane domains
the 2 possible drug bunding domains are found between transmembrane. 5/6 and 11/12
3 types of endocytotic mechanisms
NON SELECTIVE
1. fluid phase endocytosis
vesicle forms and anything within the vicinity of fluid is trapped and the vesicle fuses with membrane and transfers it across
SELECTIVE
2. receptor-mediated endocytosis
- insulin and transferring bind to its specific receptor, enveloped in vesicle and transferred and released
3. absorptive transcytosis
- positively charged molecule interacts with negatively charged glycocalyx, the positively charged molecule then engulfed in vesicle, its transferred and released
what 2 things form the blood CSF barrier
- choroid plexus (4 types)
- arachnoid membrane
3 functions of choroid plexus
- produces CSF
- synthesises polypeptides
- contributes to regulating brain ISF
what causes alzheimers disease
alzheimers disease toxin is amyloid β, the removal process is damaged
