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

Introduction to the Urinary System

Anatomy & Physiology

25. The Urinary System

Introduction to the Urinary System

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Multiple Choice

Which of the following nitrogenous wastes requires the greatest amount of water to excrete?

Ammonia

Uric acid

Urea

Creatinine

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Understand the concept of nitrogenous waste excretion: Nitrogenous wastes are byproducts of protein metabolism and are excreted by the body in different forms, depending on the organism's physiology and environment. The main types are ammonia, urea, uric acid, and creatinine.

Learn about ammonia: Ammonia (NH₃) is highly toxic and requires a large amount of water to dilute and excrete. It is typically excreted by aquatic organisms, such as fish, because they have access to abundant water to flush it out.

Compare ammonia to urea: Urea is less toxic than ammonia and requires less water for excretion. It is synthesized in the liver through the urea cycle and excreted by mammals, allowing them to conserve water.

Compare ammonia to uric acid: Uric acid is the least toxic and is excreted as a paste or solid by organisms like birds and reptiles. This form of excretion conserves the most water.

Compare ammonia to creatinine: Creatinine is a byproduct of muscle metabolism and is excreted in urine. It does not require as much water as ammonia for excretion. Therefore, ammonia requires the greatest amount of water to excrete among the listed options.