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 Nephron

Anatomy & Physiology

25. The Urinary System

The Nephron

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Multiple Choice

What happens when the concentration of Na+ decreases in the ascending limb of the nephron?

The secretion of K+ in the collecting duct decreases.

The reabsorption of water in the descending limb increases.

The reabsorption of Na+ in the distal convoluted tubule increases.

The osmolarity of the medullary interstitium decreases.

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Verified step by step guidance

Understand the function of the nephron: The nephron is the functional unit of the kidney, responsible for filtering blood and forming urine. It consists of different segments, each with specific roles in reabsorption and secretion.

Identify the role of the ascending limb of the nephron: The ascending limb of the loop of Henle is impermeable to water and actively transports Na+ and Cl- ions out of the tubular fluid into the medullary interstitium, contributing to the osmotic gradient.

Consider the effect of decreased Na+ concentration: If the concentration of Na+ decreases in the ascending limb, less Na+ is transported into the medullary interstitium, which can affect the osmotic gradient.

Analyze the impact on the medullary interstitium: A decrease in Na+ transport leads to a reduction in the osmolarity of the medullary interstitium, as there are fewer solutes to maintain the gradient.

Conclude the physiological outcome: With a decreased osmolarity in the medullary interstitium, the ability to reabsorb water in the collecting duct is affected, but the primary change is the decrease in osmolarity itself.