The Endocrine System Bio 12/12A S. Angelidis 5/27/2019

Introduction 5/27/2019

Principal Differences between the Two Communication Systems: Nervous system: Endocrine system: 5/27/2019

Endocrine System: Endocrine Gland: Hormone: 5/27/2019

Major Human Endocrine Glands 5/27/2019

Mechanism of Hormone Action 5/27/2019

Mechanisms of Hormone Action Secreting cell releases hormone. Only target cells are affected 5/27/2019

Mechanisms of Hormone Communication Hormones are released from glands and travel throughout the body via the blood stream. 5/27/2019

Types of Hormones 5/27/2019

Steroid Hormones 5/27/2019

Steroid Hormone/Receptor Entry Steroid hormones diffuse through the membrane and enter the cell directly. 5/27/2019

Target Cell Executes Hormone’s “Orders” The target cell begins to make the materials needed to carry out the hormone’s “orders”. 5/27/2019

Steroid Hormone Chemical Structure Steroid hormones are produced by modifying cholesterol molecules. 5/27/2019

Cholesterol-Based Hormones 5/27/2019

Protein Hormones Ex: Insulin 5/27/2019

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. 5/27/2019

Protein Hormone/Target Cell membrane Protein Hormone approaches target cell. 5/27/2019

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. 5/27/2019

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. 5/27/2019

Hormones & Homeostasis Negative Feedback 5/27/2019

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. 5/27/2019

Effect of Thyroxine Thyroxine 5/27/2019

Interaction between ES & NS: The Pituitary Gland 5/27/2019

The Posterior Pituitary Gland The pituitary gland is divided into 2 parts: 5/27/2019

The Anterior Pituitary Gland 5/27/2019

Pituitary Hormones 5/27/2019

Endocrine System Problems Endocrine system problems are numerous, but all fall into one of 3 major categories: 5/27/2019

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 5/27/2019