Table of contents

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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

16. The Endocrine System

Introduction to the Endocrine System

Anatomy & Physiology

16. The Endocrine System

Introduction to the Endocrine System

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Multiple Choice

Which organs are primarily involved in the synthesis of calcitriol, the active form of vitamin D?

Pancreas, thyroid, and adrenal glands

Skin, liver, and kidneys

Stomach, small intestine, and colon

Heart, lungs, and spleen

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Verified step by step guidance

Understand that calcitriol is the active form of vitamin D, which plays a crucial role in calcium and phosphate homeostasis in the body.

Recognize that the synthesis of calcitriol involves multiple organs working sequentially: the skin, liver, and kidneys.

Step 1: In the skin, ultraviolet (UV) radiation converts 7-dehydrocholesterol into cholecalciferol (vitamin D3). This is the first step in the synthesis process.

Step 2: In the liver, cholecalciferol is hydroxylated at the 25th carbon position by the enzyme 25-hydroxylase, forming 25-hydroxyvitamin D (calcidiol).

Step 3: In the kidneys, calcidiol undergoes a second hydroxylation at the 1st carbon position by the enzyme 1-alpha-hydroxylase, forming calcitriol, the biologically active form of vitamin D.