What acts as a protective barrier preventing harmful substances entering the brain?

Prepare for the VTCT Level 2 Facial and Skincare Test. Revise with flashcards and multiple choice questions, accompanied by insightful explanations. Ace your assessment with confidence!

The protective barrier is the blood-brain barrier, a selective shield formed by tightly connected endothelial cells in the brain’s capillaries and supported by astrocyte foot processes. It allows essential nutrients to pass while blocking most harmful substances from entering the brain, helping to keep the neural environment stable for proper signaling. The cerebrum is the brain’s main processing area, grey matter consists of neuron cell bodies involved in processing information, and white matter contains myelinated nerve fibers for communication between brain regions. None of these act as a barrier to external substances in the way the blood-brain barrier does, so the correct answer is the blood-brain barrier.