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Blood Brain Barrier

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

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Blood Brain Barrier

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  1. Blood Brain Barrier Abdulelah Nuqali Intern

  2. 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 • Responsible for metabolic activities such as the metabolism of L-dopa to regulate its concentration in the brain.

  3. Properties of the BBB • General Properties of the BBB • Large molecules do not pass through the BBB easily. • Low lipid (fat) soluble molecules do not penetrate into the brain. However, lipid soluble molecules rapidly cross the BBB into the brain. • Molecules that have a high electrical charge to them are slowed.

  4. Integrity of BBB • Tight Junctions • Adherens Junctions • Pericytes • Astrocyte end feet

  5. Structure of Blood Brain Barrier

  6. Differences between BMEC and normal endothelial cells • Structural differences: • Absence of fenestrations • More extensive tight junctions (TJ)

  7. Regions of brain not enclosed by BBB • Circumventricular organs • area postrema, • median eminence, • neurohypophysis, • pineal gland, • subfornical organ and • lamina terminalis These are regions which need to respond to factors present in systemic circulation

  8. 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 Plexus • Area Postrema - the “vomiting centre” of the brain • Median eminence - regulates the anterior pituitary through the release of neurohormones • Neurohypophysis - detects levels of oxytocin and ADH in the blood

  9. Opening of the BBB • 1 – Physiological • 2 – pathological : • Traumatic brain injury • Ischaemic stroke • Septic encephalopathy • Tumour Increase BBB premeability cerebral edema

  10. Transport of drugs across the BBB • Lipophilicity • Molecular weight

  11. Reference K. Lawther, Sajith Kumar, Hari Krovvidi , Blood–brain barrier, Continuing Education in Anaesthesia, Critical Care & Pain | Volume 11 Number 4, 2011

  12. Thanks

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