Which among the following statement/s best explain/s the role of Blood Brain Barrier?
(I) It controls the oxygen supply to the brain
(II) It protects the nervous system from toxins and viruses
(III) Allows the free flow of molecules across the brain
(IV) Hypertension can compromise the blood brain barrier

Correct option is C

The blood-brain barrier (BBB) serves as a selective permeability barrier that protects the central nervous system from potentially harmful substances in the bloodstream, including toxins and pathogens (statement II is correct). Additionally, conditions like chronic hypertension can damage and compromise the integrity of the blood-brain barrier (statement IV is correct), leading to increased permeability and potential neurological complications.

Information Booster:
1. Protective Function: The BBB is formed by tight junctions between endothelial cells in brain capillaries, creating a selective barrier that prevents harmful substances from entering brain tissue
2. Selective Permeability: Allows essential nutrients (glucose, amino acids) to pass while blocking most pathogens, toxins, and large molecules
3. Hypertension Effects: Chronic high blood pressure can cause structural damage to BBB, increasing permeability and potentially leading to conditions like vascular dementia
4. Disease Implications: BBB compromise is associated with various neurological disorders including multiple sclerosis, Alzheimer's disease, and stroke
5. Therapeutic Challenge: The BBB's protective function also makes drug delivery to the brain difficult, requiring special strategies for neurological treatments