Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

12. The Central Nervous System

Introduction to the Central Nervous System

Anatomy & Physiology

12. The Central Nervous System

Introduction to the Central Nervous System

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Multiple Choice

The blood-brain barrier is effective against which of the following?

Most bacteria and toxins

Glucose

Oxygen and carbon dioxide

Lipid-soluble substances

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Verified step by step guidance

Step 1: Understand the concept of the blood-brain barrier (BBB). The BBB is a selective permeability barrier formed by endothelial cells in the brain's capillaries. It protects the brain by preventing harmful substances, such as bacteria and toxins, from entering the brain tissue while allowing essential nutrients and gases to pass through.

Step 2: Analyze the substances listed in the problem. The options include: 'Most bacteria and toxins,' 'Glucose,' 'Oxygen and carbon dioxide,' and 'Lipid-soluble substances.' Each of these interacts differently with the BBB based on its properties.

Step 3: Recall the mechanisms of transport across the BBB. The BBB allows small, lipid-soluble substances to diffuse freely, while larger or water-soluble molecules require specific transport mechanisms. Essential molecules like glucose are transported via facilitated diffusion, and gases like oxygen and carbon dioxide pass through by simple diffusion.

Step 4: Evaluate the effectiveness of the BBB against harmful substances. The BBB is highly effective at blocking most bacteria and toxins due to its tight junctions and selective transport mechanisms. However, lipid-soluble substances can bypass the barrier, which is why some drugs and alcohol can affect brain function.

Step 5: Conclude that the BBB is effective against 'Most bacteria and toxins,' as these are harmful substances that the barrier is specifically designed to block, while allowing essential molecules like glucose, oxygen, carbon dioxide, and lipid-soluble substances to pass through.