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Blood Brain Barrier. Abdulelah Nuqali Intern. What is the Blood Brain Barrier?. Structural and functional Formed by brain microvascular endothelial cells (BMEC), astrocyte end feet and pericytes Essential for normal function of CNS - PowerPoint PPT Presentation
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Abdulelah NuqaliIntern
What is the Blood Brain Barrier?
Structural and functionalFormed by brain microvascular endothelial cells
(BMEC), astrocyte end feet and pericytesEssential for normal function of CNSResponsible for metabolic activities such as the
metabolism of L-dopa to regulate its concentration in the brain.
Properties of the BBBGeneral Properties of the BBB
1. Large molecules do not pass through the BBB easily.
2. Low lipid (fat) soluble molecules do not penetrate into the brain. However, lipid soluble molecules rapidly cross the BBB into the brain.
3. Molecules that have a high electrical charge to them are slowed.
Integrity of BBBTight JunctionsAdherens JunctionsPericytesAstrocyte end feet
Structure of Blood Brain Barrier
Differences between BMEC and normal endothelial cellsStructural differences:
Absence of fenestrationsMore extensive tight junctions (TJ)
Regions of brain not enclosed by BBBCircumventricular organs
area postrema, median eminence, neurohypophysis, pineal gland, subfornical organ and lamina terminalisThese are regions which need to respond to
factors present in systemic circulation
Circumventricular organ functions:
Pineal gland - secretes melatonin and is associated with circadian rhythms
Subfornical organ - regulates body fluids, fluid and electrolyte imbalance
Organum vasculosum of the lamina terminalis – detects peptides
Choroid PlexusArea Postrema - the “vomiting centre” of the
brainMedian eminence - regulates the anterior
pituitary through the release of neurohormonesNeurohypophysis - detects levels of oxytocin and
ADH in the blood
Opening of the BBB 1 – Physiological2 – pathological :
i. Traumatic brain injuryii. Ischaemic strokeiii. Septic encephalopathyiv. Tumour
Increase BBB premeability cerebral edema
Transport of drugs across the BBBLipophilicityMolecular weight
ReferenceK. Lawther, Sajith Kumar, Hari Krovvidi , Blood–brain barrier,
Continuing Education in Anaesthesia, Critical Care & Pain | Volume 11 Number 4, 2011
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