1. The Endocrine System
Bio 12/12A
S. Angelidis
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2. Introduction
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3. Principal Differences between the Two Communication Systems:
Nervous system:
Endocrine system:
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4. Endocrine System:
Endocrine Gland:
Hormone:
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5. Major Human Endocrine Glands
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6. Mechanism of Hormone Action
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7. Mechanisms of Hormone Action
Secreting cell releases hormone.
Only target cells are affected
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8. Mechanisms of Hormone Communication
Hormones are released from glands and travel throughout the body via the blood stream.
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9. Types of Hormones
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10. Steroid Hormones
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11. Steroid Hormone/Receptor Entry
Steroid hormones diffuse through the membrane and enter the cell directly.
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12. Target Cell Executes Hormone’s “Orders”
The target cell begins to make the materials needed to carry out the hormone’s “orders”.
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13. Steroid Hormone Chemical Structure
Steroid hormones are produced by modifying cholesterol molecules.
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14. Cholesterol-Based Hormones
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15. Protein Hormones
Ex: Insulin
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16. Protein Hormone Receptors
Receptors located in the target cell membrane
Binding of hormone with receptor starts chain of reactions that make up the cell’s response to the hormone.
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17. Protein Hormone/Target Cell membrane
Protein Hormone approaches target cell.
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18. Binding of Protein Hormone to Target Cell Receptor Site
Binding with hormone causes receptor to react with G-protein located on inner layer of the cell membrane.
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19. Activation of AC & Production of cAMP
G-protein activates AC which then produces cAMP.
cAMP delivers hormone’s “orders” to other cell enzymes.
These produce the appropriate response.
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20. Hormones & Homeostasis Negative Feedback
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21. An Example of the Negative Feedback Process
A low level of thyroxine causes the manufacture of more.
A high level of thyroxine has a negative effect on its production.
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22. Effect of Thyroxine
Thyroxine
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23. Interaction between ES & NS: The Pituitary Gland
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24. The Posterior Pituitary Gland
The pituitary gland is divided into 2 parts:
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25. The Anterior Pituitary Gland
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26. Pituitary Hormones
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27. Endocrine System Problems
Endocrine system problems are numerous, but all fall into one of 3 major categories:
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28. Where to Get More Information (Besides textbook)
Both sites listed below have information on the ES. They are “linked” so clicking on either one will take you to that site.
An On-Line Biology Book
Kimball's Biology Pages
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