Blood Brain Barrier and intracranial pressure Flashcards
(59 cards)
Which ion is at higher concentrations in the CSF than blood?
Sodium ions
The main difference of the choroid epithelia compared to other epithelia is
The apical location of Na+, K+ ATPase, and Na+, K+, 2Cl- cotransporter, and high CA activity. In normal epithelia, only Cl- is on the apical side.
What are 3 drugs that inhibits CSF secretion by the choroid plexus?
Acetazolamide, Bumetanide, Furosemide
Acetazolamide
Decreases CSF secretion by inhibiting the carbonic anhydrase enz
Furosemide
Blocks K-Cl cotransport by KCC3
Bumetanide
Blocks the Na-K-2Cl cotransporter of the choroid plexus (BCSFB)
difference between the choroid plexus blood-csf barrier and the blood brain barrier
The BCSFB has fenestrated capillaries and ependymal cells that produce CSF.
The BBB has tight junctions in their endothelial cells and don’t cell much pass. They also have astrocytic foot processes.
Absorption of CSF
Arachnoid villi, massive vacuoles
Venous thrombosis
E.g. cerebral venous thrombosis (CVT) can increase intracranial pressure, but rarely cause hydrocephalus
Glymphatic system
The glymphatic system is a recently discovered macroscopic waste clearance system that utilizes a unique system of perivascular channels, formed by astroglial cells, to promote efficient elimination of soluble proteins and metabolites from the central nervous system, which is more active during REM sleep and may be involved with Alzheimer’s and depression.
What is the pathological change in the glympathic system that causes Alzheimer’s or normal pressure hydrocephalus?
Altered AQP4 expression
Obstruction of CSF causes
Dilation of the venticular system proximal to the obstruction with profound effect on intracranial pressure.
Choroid plexus papilloma
causes increased production of CSF, and causes communicating hydrocephalus
Normal pressure hydrocephalus
Adam’s triad: Gait disturbances, dementia, urinary incontinence. Can be cured. Probable etiology is decreased reabsorption of CSF through arachnoid granulations.
The CSF tap test, also called a large-volume
lumbar puncture, involves the
withdrawal of
40–50 ml of CSF by means of lumbar puncture.
Symptomatic improvement after the CSF tap test means that
Increased likelihood of a favorable
response to shunt placement (positive predictive value 73–100%).
Ventriculoperitoneal Shunt
Shunt from lateral ventricles into peritoneal cavity, helps with normal pressure hydrocephalus
Virchow-Robin space
Space betweem the capillaries in the brain and the glial endfeet
Intrathecal drug delivery applications
Chemotherapy (methotrexate, cystosine arabinoside, meningeal spread - leukemia), spinal anesthesia, steroids for pain relief, antisense oligonucleotides
Clinical application of CNS immune privilege
Nerve cell transplant e.g. ventral midbrain cells can survive up to 14 years in PD patients
4 possible theories behind how CNS has immune privilege
- BBB, 2. Lack of lymphatic drainage, 3. Lack of potent APCs, 4. Presence of immunosuppressive factors e.g. TGF-beta, FASL, ganglioside, PDL1
Blood brain barrier
- Endothelial cells with TIGHT JUNCTIONS 2. Continuous capillaries 3. Foot processes of astrocytes (not a barrier)
Two regions in the brain lacking BBB (with fenestrated capillaries)
the area postrema, posterior pituitary area
