In the second half of our look at the endocrine system, Hank discusses chemical homeostasis and hormone cascades. Specifically, he looks at the hypothalamus-pituitary-thyroid axis, or HPT axis, and all the ways your body can suffer when that system, or your hormones in general, get out of whack.

Table of Contents
Chemical Homeostasis 1:04
Hormone Cascades 2:37
HPT Axis 3:25

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1. Introduction to Anatomy & Physiology
2. Tissues, Part 1
3. Tissues, Part 2 - Epithelial Tissue
4. Tissues, Part 3 - Connective Tissues
5. Tissues, Part 4 - Types of Connective Tissues
6. The Integumentary System, Part 1: Skin Deep
7. The Integumentary System, Part 2: Skin Deeper
8. The Nervous System, Part 1
9. The Nervous System, Part 2: Action! Potential!
10. The Nervous System, Part 3: Synapses!
11. Central Nervous System
12. Peripheral Nervous System
13. Autonomic Nervous System
14. Sympathetic Nervous System
15. Parasympathetic Nervous System
16. Taste & Smell
17. Hearing & Balance
18. Vision
19. The Skeletal System
20. Joints
21. Muscles, Part 1 - Muscle Cells
22. Muscles, Part 2 - Organismal Level
23. Endocrine System, Part 1 - Glands & Hormones
24. Endocrine System, Part 2 - Hormone Cascades
25. The Heart, Part 1 - Under Pressure
26. The Heart, Part 2 - Heart Throbs
27. Blood Vessels, Part 1 - Form and Function
28. Blood Vessels, Part 2
29. Blood, Part 1 - True Blood
30. Blood, Part 2 - There Will Be Blood
31. Respiratory System, Part 1
32. Respiratory System, Part 2
33. Digestive System, Part 1
34. Digestive System, Part 2
35. Digestive System, Part 3
36. Metabolism & Nutrition, Part 1
37. Metabolism & Nutrition, Part 2
38. Urinary System, Part 1
39. Urinary System, Part 2
40. Reproductive System, Part 1: Female Reproductive System
41. Reproductive System, Part 2: Male Reproductive System
42. Reproductive System, Part 3: Sex & Fertilization
43. Reproductive System, Part 4: Pregnancy & Development
44. Lymphatic System
45. Immune System, Part 1
46. Immune System, Part 2
47. Immune System, Part 3

In this Crash Course series, Hank Green teaches most of what you should know about anatomy and physiology, perfect for a freshman-level biology course, or just your own curiosity about the human body.