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

19. The Blood Vessels

Introduction to Blood Vessels

Anatomy & Physiology

19. The Blood Vessels

Introduction to Blood Vessels

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Multiple Choice

Which type of blood vessel typically lacks one or more of the three tunics?

Arterioles

Capillaries

Arteries

Veins

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Verified step by step guidance

Understand the structure of blood vessels: Blood vessels are composed of three tunics (layers) - the tunica intima (inner layer), tunica media (middle layer), and tunica externa (outer layer). These layers vary in thickness and composition depending on the type of blood vessel.

Review the characteristics of capillaries: Capillaries are the smallest blood vessels and are specialized for exchange of gases, nutrients, and waste between blood and tissues. Unlike other blood vessels, capillaries lack the tunica media and tunica externa, consisting only of the tunica intima, which is a single layer of endothelial cells.

Compare capillaries to other blood vessels: Arteries, veins, and arterioles all have the three tunics, although their thickness and composition differ. For example, arteries have a thick tunica media to withstand high pressure, while veins have a thinner tunica media and valves to prevent backflow.

Identify the correct answer: Based on the structural differences, capillaries are the type of blood vessel that typically lacks one or more of the three tunics, as they only have the tunica intima.

Conclude the reasoning: Capillaries are uniquely adapted for their function in exchange processes, and their lack of tunica media and tunica externa allows for efficient diffusion of substances between blood and tissues.