Which of the Following Statements is TRUE Regarding the Blood-Brain

Question

Which of the following statements is TRUE regarding the blood-brain barrier (BBB)?
A) The endothelial cells of the BBB are extensively interconnected with tight junctions.
B) Lipid-soluble compounds can freely diffuse across the endothelial cell membranes.
C) Endothelial transport across the BBB is highly selective.
D) The endothelial cells of the BBB contain small numbers of pinocytotic vesicles.
E) All of these are characteristics of the BBB.

Accepted Answer

All the statements provided (A, B, C, D) accurately describe characteristics of the blood-brain barrier (BBB). The BBB's endothelial cells are tightly interconnected with tight junctions, allowing for selective permeability. Lipid-soluble compounds can indeed diffuse across the endothelial cell membranes due to their solubility in the lipid bilayer. The transport across the BBB is highly selective, ensuring that only specific substances necessary for brain function can pass through. Lastly, the endothelial cells contain few pinocytotic vesicles, which is significant for maintaining the barrier's selective permeability.