Chapter 18, part 1

1. Chapter 18, part 1 The Endocrine System

2. Learning Objectives • Compare the major chemical classes and general mechanisms of hormones. • Describe the location and structure of the pituitary gland, and explain its structural and functional relationships with the hypothalamus. • Describe the location and structure of each of the endocrine glands.

3. Learning Objectives • Identify the hormones produced by each of the endocrine glands and specify the functions of those hormones. • Describe the functions of the hormones produced by the kidneys, heart, thymus, testes, ovaries and adipose tissue. • Explain how hormones interact to produce coordinated physiological responses.

4. SECTION 18-1Intercellular Communication

5. Endocrine versus Nervous system • Nervous system performs short term crisis management • Endocrine system regulates long term ongoing metabolic • Endocrine communication is carried out by endocrine cells releasing hormones • Alter metabolic activities of tissues and organs • Target cells • Paracrine communication involves chemical messengers between cells within one tissue

6. SECTION 18-2An Overview of the Endocrine System

7. Endocrine system • Includes all cells and endocrine tissues that produce hormones or paracrine factors

8. Figure 18.1 The Endocrine System Figure 18.1

9. Hormone structure • Amino acid derivatives • Structurally similar to amino acids • Peptide hormones • Chains of amino acids • Lipid derivatives • Steroid hormones and eicosanoids

10. Figure 18.2 A Structural Classification of Hormones Figure 18.2

11. Hormones can be • Freely circulating • Rapidly removed from bloodstream • Bound to transport proteins

12. Mechanisms of hormone action • Receptors for catecholamines, peptide hormones, eicosanoids are in the cell membranes of target cells • Thyroid and steroid hormones cross the membrane and bind to receptors in the cytoplasm or nucleus

13. Figure 18.3 G Proteins and Hormone Activity Figure 18.3

14. Figure 18.4 Hormone Effects on Gene Activity Figure 18.4

15. Control of endocrine activity • Endocrine reflexes are the counterparts of neural reflexes • Hypothalamus regulates the activity of the nervous and endocrine systems • Secreting regulatory hormones that control the anterior pituitary gland • Releasing hormones at the posterior pituitary gland • Exerts direct neural control over the endocrine cells of the adrenal medullae

16. Figure 18.5 Three Methods of Hypothalamic Control over the Endocrine System Figure 18.5

17. SECTION 18-3The Pituitary Gland

18. Hypophysis • Releases nine important peptide hormones • All nine bind to membrane receptors and use cyclic AMP as a second messenger

19. Figure 18.6 The Anatomy and Orientation of the Pituitary Gland Figure 18.6a, b

20. The anterior lobe (adenohypophysis) • Subdivided into the pars distalis, pars intermedia and pars tuberalis • At the median eminence, neurons release regulatory factors through fenestrated capillaries • Releasing hormones • Inhibiting hormones