1. Abdulelah Nuqali Intern
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

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

8. 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

9. 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

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

11. Transport of drugs across the BBB
Lipophilicity
Molecular weight

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

13. Thanks