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

25. The Urinary System

The Kidneys

Anatomy & Physiology

25. The Urinary System

The Kidneys

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Multiple Choice

Which labeled structure in the kidney is primarily responsible for passive water reabsorption?

Proximal convoluted tubule

Descending limb of the loop of Henle

Glomerulus

Collecting duct

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Verified step by step guidance

Understand the function of each structure listed in the kidney: The proximal convoluted tubule, descending limb of the loop of Henle, glomerulus, and collecting duct. Each plays a distinct role in filtration, reabsorption, or secretion.

Recall that passive water reabsorption occurs due to osmosis, which is driven by the concentration gradient of solutes. Identify which structure is specialized for this process.

Examine the descending limb of the loop of Henle: This structure is permeable to water but not to solutes, allowing passive water reabsorption as the filtrate moves deeper into the medulla where the solute concentration is higher.

Compare the descending limb of the loop of Henle to the other structures: The proximal convoluted tubule reabsorbs water actively along with solutes, the glomerulus is involved in filtration, and the collecting duct reabsorbs water under hormonal control (e.g., ADH).

Conclude that the descending limb of the loop of Henle is primarily responsible for passive water reabsorption due to its unique permeability and the osmotic gradient in the kidney medulla.