The Application of Endocrinology to Selected Animals and Humans (Chapter 11)

1. The Application of Endocrinology to Selected Animals and Humans (Chapter 11) • Efficient production – dependent on effective bodily function • Effective bodily function – dependent on endocrine glands

2. Endocrine glands – secrete hormones • Ductless – release directly into blood stream • Exocrine glands • Ducts that lead to body surfaces or into other organs • Pancreas – unique organ that is both endocrine (insulin) and exocrine (pancreatic juice into stomach) Science of Endocrinology

3. Science of Endocrinology • Hormone – means “to stimulate” • Secreted in very small quantities • 1/1,000,000 g of oxytocin will cause milk ejection • Important in: • growth and efficiency • reproduction • lactation

4. Endocrine Glands • Anterior pituitary • Affects secretions of many other endocrine organs • Posterior pituitary • Stores and releases some hypothalamus hormones • Hypothalamus • Small area of brain that regulates hormonal activity • Several others scattered around body

5. Chemical Nature of Hormones • Proteins and glycoproteins • Peptides • Amines • Steroids • Non-steriodal

6. Hypothalmus Hormones • Growth hormone-releasing hormone (GnRH) • Stimulates release of growth hormone • Growth hormone inhibiting hormone (somatostatin) • Inhibits release of growth hormone • Prolactin-releasing hormone (PRH) • Stimulates release of prolactin

7. Prolactin-inhibiting hormone (PIH) • Inhibits release of prolactin • Oxytocin • Ejection of milk, expulsion of eggs, uterine contractions • Vasopressin • Constriction of peripheral blood vessels and water resorption in the kidney tubules Hypothalmus Hormones

8. Growth hormone (GH, somatotropin) • Promotes growth of tissues • Adrenocorticotropin (ACTH) • Stimulates secretion of steroids (especially glucocorticoids (from adrenal cortex) • Thyroid-stimulating hormone (TSH) • Stimulates thyroid gland to secrete thyroxine Anterior Pituitary Hormones

9. Prolactin • Initiates lactation and stimulates maternal behavior • Follicle stimulating hormone (FSH) • Stimulates follicle development in the female and sperm production in the male • Luteinizing hormone (LH) • Maturation of follicles and ovulation in female, testosterone production in testes by male Anterior Pituitary Hormones

10. Thyroid Hormones • Thyroxine, triiodothyronine • Increases metabolic rate • Calcitonin • Lowers concentration of calcium in the blood and promotes incorporation of calcium into the bone

11. Parathyroid Hormones • Parathyroid Hormone • Maintains or increases the level of blood calcium and phosphorus

12. Adrenal Cortex Hormones • Glucocorticoids • Mobilizes energy, increases blood glucose, antistress • Mineralocorticoids • Maintains salt and water balance in the body

13. Adrenal Medulla Hormones • Epinephrine • Stimulates heart muscles and rate and strength of their contraction • Norepinephrine • Stimulates smooth muscles and glands and maintains blood pressure

14. Ovarian Follicle Hormone • Estrogens • Growth of the reproductive tract and mammary duct system

15. Progesterone • Prepares reproductive tract for pregnancy, maintains pregnancy and causes development of mammary lobule-alveolar system • Relaxin • Causes relaxation of ligaments and cartilage in pelvis, assists in parturition Ovarian Corpus Luteum Hormones

16. Uterus Hormone • Prostaglandin F2α(PGF2α) • Causes luteolysis and a decrease in progesterone

17. Testicular Hormones • Androgens (testosterone) • Causes maturation of sperm • Promotes development of male accessory glands • Promotes development of secondary sex characteristics

18. Pancreatic Hormones • Insulin • Lowers blood glucose • Glucagon • Raises blood glucose

19. Placenta (in some species) Hormones • Gonadotropins, estrogen, progesterone • Promotes maintenance of pregnancy • Some names for placental gonadotropins • Pregnant mare serum • Equine chorionic gonadotropin • Human chorionic gonadotropins

20. Functions of Hormones • Small amounts needed • Affect growth, body shape, food use, reproduction • Many quickly deactivated when administered • May disappear in few hours • Act quickly but effect may not be noticeable until later

21. Hormones released into, and travel through circulatory system • Attach to receptors that are specific to each hormone • Once attached to receptor, action will be carried out in the cell Mechanism of Hormone Action

22. Endocrine activity must be carefully balanced • Regulation is important • Feedback mechanism • Interaction between two hormones may regulate secretion of both • Chemical homeostasis • Blood level of non-hormone chemicals affected by hormones may regulate secretion Regulation of Hormone Secretion

23. Birth control pills • Many have combination of synthetic progesterone and synthetic estrogen • Synchronize estrus - Progestins, PGF2α • Superovulation – Gonadotropins • Treatment of cystic ovaries – Gonadotropin releasing hormone Uses of Natural and Synthetic Hormones

24. Uses of Natural and Synthetic Hormones • Induction of lactation (not approved by FDA) • Administration of estrogen and progesterone • Increase rate and efficiency of gain • Estrogens and synthetic estrogens • Melengestrol acetate (MGA) – synthetic progesterone

25. Hormones and Public Health • Possibility of residues in food produced by animals treated with hormones • Has not become a public health problem • Prevention of residues is high priority