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

Which substance is secreted by the nephrons during urine formation?

Amino acids

Glucose

Potassium ions

Red blood cells

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Verified step by step guidance

Understand the role of nephrons in urine formation: Nephrons are the functional units of the kidney responsible for filtering blood, reabsorbing essential substances, and secreting waste products into the urine.

Identify the process of secretion: Secretion in the nephron involves the active transport of substances from the blood in the peritubular capillaries into the tubular fluid. This process helps maintain electrolyte balance and remove excess ions or waste products.

Analyze the substances listed: Amino acids and glucose are typically reabsorbed in the proximal tubule of the nephron because they are valuable nutrients. Red blood cells are too large to pass through the filtration barrier and are not secreted into the urine under normal conditions.

Focus on potassium ions: Potassium ions (K⁺) are actively secreted by the distal tubule and collecting duct of the nephron. This secretion is regulated by hormones like aldosterone to maintain proper potassium levels in the blood.

Conclude that potassium ions are the correct answer: Potassium ions are secreted by the nephrons during urine formation, while the other substances listed are either reabsorbed or not involved in secretion under normal physiological conditions.