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

What prevents the backflow of blood in veins?

Smooth muscle contraction

Capillary sphincters

Arterial pressure

Valves

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Verified step by step guidance

Understand the structure of veins: Veins are blood vessels that carry blood back to the heart. Unlike arteries, veins have thinner walls and larger lumens.

Recognize the role of valves in veins: Veins, especially in the limbs, contain one-way valves that prevent the backflow of blood, ensuring it moves towards the heart.

Differentiate between veins and other blood vessels: Arteries do not have valves because the high pressure from the heart's pumping action keeps blood moving forward. Capillaries, being very small, do not have valves either.

Consider the effect of gravity: In the lower body, gravity can cause blood to pool in the veins. Valves help counteract this by preventing backflow and assisting venous return to the heart.

Identify the incorrect options: Smooth muscle contraction helps in moving blood but does not prevent backflow. Capillary sphincters regulate blood flow into capillaries, not veins. Arterial pressure is related to arteries, not veins.