PMCOL 412 Midterm 1 Exam Questions With Correct Answers
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Course
PMCOL 412
Institution
PMCOL 412
PMCOL 412 Midterm 1 Exam Questions
With Correct Answers
Blood-brain barrier - answer"mechanical membrane" that separates blood from the brain,
physical and biochemical barrier
Info on brain capillaries - answerThe brain receives 20% of cardiac output, the capillary
length is 400 miles, the cap...
PMCOL 412 Midterm 1 Exam Questions
With Correct Answers
Blood-brain barrier - answer✔"mechanical membrane" that separates blood from the brain,
physical and biochemical barrier
Info on brain capillaries - answer✔The brain receives 20% of cardiac output, the capillary
length is 400 miles, the capillary surface area is 20 m^2, and distances between capillaries is 40
μm
Role of BBB - answer✔Controls and regulates the access of molecules from blood to brain to
maintain homeostasis of brain microenvironment
What 3 types of cells form BBB? - answer✔endothelial cells, pericytes, and astrocytes
endothelial cells - answer✔-mainly exerts for barrier function
-highly polarized, TJ segregate apical (luminal) and basal (abluminal) domains
-secrete platelet-derived growth factor (PDGF-B) to recruit pericytes for vascular maturation
pericytes and astrocytes - answer✔crucial in development and maintenance of barrier function
What also contributes to BBB properties - answer✔Perivascular inter-neurons and microglia
What brain areas do not have a BBB? (fenestrated capillaries-lack pericyte and astrocyte
ensheathment to allow hydrophilic entry) - answer✔Area postrema, circumventricular organs
and regions of hypothalamus
Why do some brain areas don't have a BBB? - answer✔To sample general circulation and
direct adaptive responses
Features of BBB - answer✔-Endothelial cells of the BBB have no fenestrations (sinusoid
larger)
-Transcellular transport through pinocytosis is minimal
-Efflux transport system removes small molecules from endothelial cells before they reach brain
parenchima
-Enzymatic systems at BBB constitute another barrier to inactivate many neuroactive and toxic
compounds
What about diffusion and paracellular transport? - answer✔Minimal diffusion in brain since
neurons are individually perfused by blood vessel
Paracellular is negligible
Structure of tight junctions - answer✔Structural transmembrane proteins:
-Occludins for TJ regulation
-Claudins for TJ tightness
-Junctional adhesion meolecules (JAM) for TJ stability & maintenance
Combined these TJ proteins: - answer✔Anchor the transmembrane proteins to cytoskeleton and
modulate junction tightness
Transendothelial electrical resistance (TEER) - answer✔Resistance to an electrical current as a
measure of ionic permeability
BBB & TEER relationship - answer✔TEER increases in brain compared to peripheral because
of tight junction presence/tightness
BBB in species and young stages - answer✔BBB in all vertebrates
Species difference in postnatal maturation
Should take into consideration higher permeability of fetal and neonatal BBB
BBB development - answer✔Early embryonic development: neural stem cells > produce Wnt >
stimulate endothelial cells to express BBB molecules
Pericytes and astrocytes contribute to BBB development, maturation, & MAINTENANCE
Astrocytes - answer✔-Astrocytic endfeet
-Contribute to neurovascular coupling
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