1. Human Anatomy, 3rd edition Prentice Hall, © 2001 Endocrine & Reproductive Systems Chapter 19 & 27

2. Human Anatomy, 3rd edition Prentice Hall, © 2001 Introduction –The endocrine system consists of cells, tissues, & organs that secrete hormones into the blood –Hormone – an organic substance secreted by a cell that has an effect on the metabolic activity of another cell or tissue –Target cells – cells that are affected by the hormone Have specific receptors for the hormones –Types of hormones Steroid Amino acid derivative Peptide

3. Human Anatomy, 3rd edition Prentice Hall, © 2001 How Hormones Work –Activation of 2 nd messengers Hormone (first messenger) binds to a receptor on the plasma membrane Receptor/hormone complex activates another substance in the cell (2 nd messenger) which then triggers the cell’s response –Activation of genes Hormone crosses the cell membrane Hormone binds to a receptor in the cytoplasm or the nucleus Receptor/hormone complex binds to the DNA and alters gene activity

4. Human Anatomy, 3rd edition Prentice Hall, © 2001 How Hormones Work

5. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Hypothalamus –Three methods of endocrine regulation Sympathetic neurons control the adrenal medulla Releases hormones –Antidiuretic hormone (ADH) –Oxytocin Secretes regulatory hormones (regulatory factors) that control the anterior pituitary gland –Releasing factors –Inhibiting factors

6. Human Anatomy, 3rd edition Prentice Hall, © 2001 Hypothalamic Regulation

7. Human Anatomy, 3rd edition Prentice Hall, © 2001 Overview of the Endocrine System

8. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Pituitary Gland –aka hypophysis = “growing below” Located in sella turcica Connected to the hypothalamus by the infundibulum –Master gland of the endocrine system –2 parts Posterior pituitary = Neurohypophysis –“Nervous part” Anterior pituitary = adenohypophysis –Hypophyseal portal veins supply the anterior pituitary from the hypothalamus

9. Human Anatomy, 3rd edition Prentice Hall, © 2001 Hypophyseal Portal System –Carries RFs and IFs from the hypothalamus to the anterior pituitary –2 capillary beds connected by portal veins –Median eminence – neurons secrete regulatory factors Diffuse into fenestrated capillaries –Portal veins connect to second capillary network in anterior pituitary Releasing factors diffuse out, stimulate surrounding endocrine cells

10. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Pituitary Gland

11. Human Anatomy, 3rd edition Prentice Hall, © 2001 Posterior Pituitary Hormones –Neurohypophysis is nervous tissue Cell bodies are in the hypothalamus –Make hormones Axons run down the infundibulum –Carry hormones to axon terminals Axon terminals are in the posterior pituitary –Store hormones –Produces 2 hormones Antidiuretic hormone (ADH) –Target – kidneys –Effect – reabsorption of water Oxytocin –Targets – reproductive organs –Effects – contractions of smooth muscles (labor contractions, milk ejection; ductus deferens, prostate gland – ejaculations)

12. Human Anatomy, 3rd edition Prentice Hall, © 2001 Anterior Pituitary Hormones –Gonadotropins stimulate growth & development of gonads Follicle stimulating hormone (FSH) stimulates gametes –Targets – follicle cells (females), testes (males) –Effects – follicle development & estrogen secretion (females), sperm maturation (males) Luteinizing hormone (LH) –Targets – follicle cells (females), interstitial cells of testes (males) –Effects – ovulation, formation of corpus luteum, secretion of progesterone (females), testosterone secretion (males)

13. Human Anatomy, 3rd edition Prentice Hall, © 2001 Anterior Pituitary Hormones –Thyroid stimulating hormone (TSH) Target – thyroid gland Effect – triggers the release of thyroid hormones –Adrenocorticotropic hormone (ACTH) Target – adrenal cortex Effect – cells that produce steroid hormones called glucocorticoids

14. Human Anatomy, 3rd edition Prentice Hall, © 2001 Anterior Pituitary Hormones –Prolactin Target - breast Effect - stimulates milk production –Growth hormone Target – all cells Effect - stimulates growth in general and the skeletal system in particular –Melanocyte stimulating hormone (MSH) Target - melanocytes Effect – increases melanin production and distribution

15. Human Anatomy, 3rd edition Prentice Hall, © 2001 Pituitary Hormones

16. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Thyroid Gland –Location – inferior to thyroid cartilage –Thyroid follicles Follicle cells make thyroglobulin (contains tyrosine) & absorb iodine from the interstitial fluid Tyrosine + iodine makes thyroxine (T4) or triiodothyronine (T3) Target cells – most cells Effect of thyroid hormones – increase energy utilization, oxygen consumption, growth, development Thyroid hormone release is controlled by TSH from the anterior pituitary –Structure also includes C cells Produce calcitonin (CT) Targets – bone, kidneys Effect of calcitonin – lowers blood calcium levels

17. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Thyroid Gland

18. Human Anatomy, 3rd edition Prentice Hall, © 2001 Thyroid Follicles and C Cells

19. Human Anatomy, 3rd edition Prentice Hall, © 2001 Control of Thyroid Hormones

20. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Parathyroid Glands –Location – posterior surfaces of the thyroid gland –Principal cells (chief cells) produce parathyroid hormone (PTH) –Target cells – bone, kidneys, intestines –Effect of PTH – increases blood calcium levels

21. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Parathyroid Glands

22. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Thymus –Location – posterior to the sternum –Produces thymosins which enhance lymphycyte production –Development Childhood – large Puberty – largest Adulthood – decreases in size

23. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Thymus Gland

24. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Adrenal Gland –Location – on top of the kidney –Structure – outer cortex and inner medulla –Medulla Secretes epinephrine & norepinephrine Target – most cells Effect –Epinephrine – increase cardiac activity, blood pressure, blood glucose; constricts blood vessels in skin, dilates blood vessels in skeletal & cardiac muscle –Norepinephrine – increases cardiac activity, constricts most blood vessels

25. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Adrenal Glands –The adrenal cortex is composed of 3 layers Zona glomerulosa secretes mineralocorticoids, mostly aldosterone –Target – kidneys –Effect – increases blood sodium levels, decreases blood potassium levels Zona fasciculata – secretes glucocorticoids (cortisol, corticosterone) –Target – most cells –Effect – conserve blood glucose, anti-inflammatory effects –Controlled by ACTH Zona reticulares – secretes androgens –Effects are uncertain

26. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Adrenal Glands

27. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Adrenal Glands

28. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Pancreas –Location – between the spleen and the duodenum –Its functions are both exocrine and endocrine –The endocrine cells are in the Islets of Langerhans Alpha cells secrete glucagon –Targets – liver, adipose tissues –Effect - increase blood sugar levels Beta cells secrete insulin –Most cells –Effect - decrease blood sugar levels Delta cells secrete somatostatin –Targets – alpha & beta cells, digestive epithelium –Effect - antagonistic to growth hormone –Diabetes mellitis

29. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Pancreas

30. Human Anatomy, 3rd edition Prentice Hall, © 2001 Islet of Langerhans

31. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Male Reproductive System –Sperm are produced in the seminiferous tubules of the testes (spermatogenesis) –Sperm are stored in the epidymus, then transported through the vas deferens, and leave the body through the urethra –Seminal fluids (semen) are added to the sperm by the seminal vesicles, prostate gland, and bulbourethral gland

32. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Male Reproductive System

33. Human Anatomy, 3rd edition Prentice Hall, © 2001 Testes –Interstitial cells secrete androgens (male sex hormones); testosterone is the most important Target – most cells Effects – maturation of sperm; protein synthesis in skeletal muscle; male secondary sex characteristics & behaviors –Some interstitial cells secrete inhibin Target – anterior pituitary Effect – inhibits the secretion of FSH

34. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Testes

35. Human Anatomy, 3rd edition Prentice Hall, © 2001 Seminiferous Tubules

36. Human Anatomy, 3rd edition Prentice Hall, © 2001 Seminiferous Tubule

37. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Female Reproductive System –Ova (oocytes) are produced in the ovaries (oogenesis) –Approximately every 28 days one ovum is expelled from the ovary (ovulation) –An ovum transported through the fallopian tube to the uterus where it becomes embedded in the uterine lining Fertilization occurs in the fallopian tube –If the egg is not fertilized, the uterine lining detaches and is shed in menstruation –If the egg is fertilized, the uterine lining is held in place and supported by progesterone

38. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Female Reproductive System

39. Human Anatomy, 3rd edition Prentice Hall, © 2001 Ovaries –Follicle cells secrete estrogen Targets – most cells Effects – follicle maturation; female secondary sex characteristics and behaviors –Follicle cells also secrete inhibin Target – anterior pituitary Effect – inhibits secretion of FSH –Corpus luteum secretes progesterone and relaxin Progesterone –Targets – uterus, mammary glands –Effects – prepare uterus for implantation and mammary glands for secretion Relaxin –Targets – pubic symphysis, uterus, mammary glands –Effects – loosens pubic symphysis, relaxes cervical muscles, stimulates mammary gland development

40. Human Anatomy, 3rd edition Prentice Hall, © 2001 Hormonal Regulation of the Female Reproductive System

41. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Pineal Gland –Location = epithalamus –Pinealocytes secrete melatonin Derived from the neurotransmitter seratonin Light inhibits production –Regulates circadian rythms Target – hypothalamus Effects – Inhibits the releasing factors that control FSH & LH secretion –Slows maturation of sperm, oocytes, & reproductive organs

42. Human Anatomy, 3rd edition Prentice Hall, © 2001 Endocrine Disorders