The blood-brain barrier is selectively permeable because of:

A Large fenestrations

B Tight junctions between endothelial cells lining brain capillaries

C Lack of blood vessels

D Thick muscle layer

✓ Correct Answer: Option B

BBB tight junctions prevent most hydrophilic and large molecules from crossing. Lipophilic drugs penetrate more readily.

💡 Why is B) the correct answer?

The correct answer to the question "The blood-brain barrier is selectively permeable because of:" is Option B: Tight junctions between endothelial cells lining brain capillaries.

The other options — A) Large fenestrations, C) Lack of blood vessels, D) Thick muscle layer — are incorrect for this PCAT Exam Prep question. As explained above: BBB tight junctions prevent most hydrophilic and large molecules from crossing. Lipophilic drugs penetrate more readily.

📚 About This PCAT Exam Prep Practice Question

This 2-level PCAT Exam Prep question from the Biological Processes topic is part of BrainForge Quiz's free exam preparation library. Each question includes the correct answer and a detailed explanation to help you understand the underlying concept, not just memorize the answer.

How to use this page: Read the question above, consider all four options (A through D), then check the highlighted correct answer and explanation. For active timed practice, start a free PCAT Exam Prep practice test or use flashcards for spaced repetition review.

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The blood-brain barrier is selectively permeable because of:

✓ Correct Answer: Option B

📚 About This PCAT Exam Prep Practice Question

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