1. Hormones & Endocrine Systems Chapter 40: pp. 735 - 754 1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (Caterpillar): © Doug Wechsler/Animals Animals/Earth Scenes; (Moth): © Richard Kolar/Animals Animals/Earth Scenes

2. Outline Endocrine Glands Pheromones Steroid Hormones Peptide Hormones Hypothalamus and Pituitary Gland Other Endocrine Glands and Hormones Thyroid Parathyroid Adrenal Pancreas Gonads 2

3. Endocrine Gland The endocrine system functions differently from the nervous system. An endocrine system consists of glands that coordinate body activities through hormones Chemical signals are used between individuals, between body parts, and between cells Both the nervous system and the endocrine system rely on negative feedback mechanisms. 3

4. The Human Endocrine System 4 ovary (female) HYPOTHALAMUS Releasing and inhibiting hormones: regulate the anterior pituitary PITUITARY GLAND Posterior Pituitary Antidiuretic (ADH): water reabsorption by kidneys Oxytocin: stimulates uterine contraction and milk letdown Anterior Pituitary Thyroid stimulating (TSH): stimulates thyroid Adrenocorticotropic (ACTH): stimulates adrenal cortex Gonadotropic (FSH, LH): egg and sperm production; sex hormone production Prolactin (PL): milk production Growth (GH): bone growth, protein synthesis, and cell division THYROID Thyroxine (T 4 ) and triiodothyronine (T 3 ): increase metabolic rate; regulates growth and development Calcitonin: lowers blood calcium level ADRENAL GLAND Adrenal cortex Glucocorticoids (cortisol): raises blood glucose level; stimulates breakdown of protein Mineralocorticoids (aldosterone): reabsorption of sodium and excretion of potassium Sex hormones: reproductive organs and bring about sex characteristics Adrenal medulla Epinephrine and norepinephrine: active in emergency situations; raise blood glucose level parathyroid glands (posterior surface of thyroid) PINEAL GLAND Melatonin: controls circadian and circannual PARA THYROIDS Parathyroid hormone (PTH): raises blood THYMUS Thymosins: production and maturation of T lymphocytes PANCREAS Insulin: lowers blood glucose level and promotes glycogen buildup Glucagon: raises blood glucose level and promotes glycogen breakdown GONADS Testes Androgens (testosterone): male sex characteristics Ovaries Estrogens and progesterone: female sex characteristics Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. testis (male)

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6. Modes of Action of the Nervous and Endocrine Systems 6 receptor neurotransmitter pancreas arteriole liver insulin liver cell axon terminal vesicle b. Reception of insulin, a hormone a. Reception of a neurotransmitter axon of nerve fiber Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

7. Chemical Signals Pheromones – Chemical signals that work at a distance between individuals – A woman’s axillary extract can alter another woman’s menstrual cycle Hormones – Chemical signals that work At a distance between organs, or Locally between adjacent cells 7

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9. Target Cell Concept 9 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. hormone capillary nontarget cell receptors target cells

10. Action of Hormones Hormones Chemical signals produced by one cell that regulate the metabolism of other cells Steroid Hormones Can cross cell membranes Peptide Hormones Most bind to receptor in plasma membrane First Messenger Causes internal release of cAMP Second Messenger 10

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13. Peptide Hormone 13 capillary receptor protein glycogen 1. Hormone binds to a receptor in the plasma membrane. activated enzyme 2. Binding leads to activation of an enzyme that changes ATP to cAMP. cAMP (second messenger) 3. cAMP activates an enzyme cascade. 4. Many molecules of glycogen are broken down to glucose, which enters the bloodstream. glucose (leaves cell and goes to blood) ATP peptide hormone (first messenger) plasma membrane Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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15. Steroid Hormone 15 ribosome protein nucleus cytoplasm 1. Hormone diffuses through plasma membrane because it is lipid soluble. steroid hormone plasma membrane nuclear pore 2. Hormone binds to receptor inside nucleus. DNA receptor protein mRNA 3. Hormone-receptor complex activates gene and synthesis of a specific mRN molecule. 4. mRNA moves to ribosomes, and protein synthesis occurs. mRNA Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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18. Human Endocrine System Endocrine glands – Ductless glands that secrete hormones directly into the bloodstream Most endocrine hormones are peptides Only gonads and adrenal cortex produce steroid hormones – Effects of hormones are moderated in two ways Negative feedback opposes release Antagonistic hormones oppose each other’s actions 18

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20. Hypothalamus and Pituitary Gland Hypothalamus regulates internal environment Acts through autonomic system Also controls glandular secretions of pituitary gland Posterior Pituitary Antidiuretic Hormone (ADH) Controlled by negative feedback Oxytocin Controlled by positive feedback Anterior Pituitary Hypothalamus controls by producing Hypothalamic-releasing hormones, and Hypothalamic-inhibiting hormones 20

21. Hypothalamus and the Pituitary 21 hypothalamus Posterior pituitaryAnterior pituitary portal system 1. Neurosecretory cells produce ADH and oxytocin. 2. These hormones move down axons to axon endings. 3. When appropriate, ADH and oxytocin are secreted from axon endings into the bloodstream. 1. Neurosecretory cells produce hypothalamic-releasing and hypothalamic-inhibiting hormones. 2. These hormones are secreted into a portal system. 3. Each type of hypothalamic hormone either stimulates or inhibits production and secretion of an anterior pituitary hormone. 4. The anterior pituitary secretes its hormones into the bloodstream, whereby they are then delivered to specific cells, tissues, and glands. Thyroid: thyroid-stimulating hormone (TSH) Adrenal cortex: adrenocorticotropic hormone (ACTH) Kidney tubules: antidiuretic hormone (ADH) Smooth muscle in uterus: oxytocin Mammary glands: oxytocin Mammary glands: prolactin (PRL) Bones, tissues: growth hormone (GH) Ovaries, testes: gonadotropic hormones (FSH, LH) optic chiasm Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

22. Anterior Pituitary Hormones Anterior pituitary hormones that affect other glands: Thyroid-Stimulating Hormone (TSH) Adrenocorticotropic Hormone (ACTH) Gonadotropic Hormones Anterior pituitary hormones that do NOT affect other glands Prolactin (PRL) Melanocyte-Stimulating Hormone (MSH) Growth Hormone (GH) 22

23. Effect of Growth Hormone 23 a: © AP/Wide World Photos; b: © Ewing Galloway, Inc. a.b. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

24. Acromegaly 24 From Clinical Pathological Conference, "Acromegaly, Diabetes, Hypermetabolism, Proteinura and Heart Failure", American Journal of Medicine, 20 (1956) 133. Reprinted with permission from Excerpta Medica Inc. Age 9Age 16Age 33Age 52 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

25. Thyroid Glands Composed of large number of follicles filled with – Triiodothyronine (T 3 ), and – Thyroxine (T 4 ) Thyroid hormones increase metabolic rate Thyroid-induced abnormalities – Simple goiter - Poor hormone production – Cretinism - Poor thyroid development – Myxedema - Hypothyroidism – Exophthalmic goiter - Hyperthyroidism 25

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27. Abnormalities of the thyroid 27 a: © Bruce Coleman, Inc./Alamy; b: © Medical-on-Line/Alamy; c: © Dr. P. Marazzi/Photo Researchers, Inc. a. Simple goiterb. Congenital hypothyroidismc. Exophthalmic goiter affected eye Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

28. Calcitonin Regulates blood calcium level (in part) Secreted by thyroid gland when blood calcium level rises Brings about deposit of calcium in the bones Low calcium level in blood stimulates the release of parathyroid hormone (PTH) – Parathyroid hormone causes Phosphate level in blood to decrease, and Calcium level in blood to increase – Insufficient production of parathyroid hormone leads to tetany 28

29. Regulation of Blood Calcium Level 29 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. calcitonin Homeostasis (normal blood Ca 2+ ) high blood Ca 2+ Thyroid gland secretes calcitonin into blood. Bones take up Ca 2+ from blood. low blood Ca 2+ Blood Ca 2+ lowers. Blood Ca 2+ rises. Parathyroid glands release PTH into blood. activated vitamin D parathyroid hormone (PTH) Intestines absorb Ca 2+ from digestive tract. Kidneys reabsorb Ca 2+ from kidney tubules. Bones release Ca 2+ into blood.

30. Adrenal Glands Paired – One sits atop each kidney (ad-renal) Each consists of outer cortex and inner medulla – Inner portion, the adrenal medulla Produces – Epinephrine, and – Norepinephrine Short-term response to stress (fight or flight) – Outer portion, adrenal cortex Produces – Mineralocorticoids, and – Glucocorticoids Long-term response to stress 30

31. Adrenal Glands 31 epinephrine norepinephrine sympathetic fibers adrenal medulla Blood glucose level rises. adrenal cortex ACTH Glucocorticoids Mineralocorticoids stress glucocorticoids mineralocorticoids hypothalamus spinal cord (cross section) neurosecretory cells produce hypothalamic- releasing hormone Stress Response: Long Term path of nerve impulses Protein and fat metabolism instead of glucose breakdown. Reduction of inflammation; immune cells are suppressed. Sodium ions and water are reabsorbed by kidney. Blood volume and pressure increase. Stress Response: Short Term Heartbeat and blood pressure increase. Muscles become energized. anterior pituitary secretes ACTH neuron cell body Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

32. Glucocorticoids Cortisol – Raises blood glucose level – Promotes breakdown of muscle proteins to amino acids – Promotes metabolism of fatty acids – Counteracts inflammatory response 32

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34. Mineralocorticoids Aldosterone Promotes two renal functions: Absorption of sodium, and Excretion of potassium Renin-angiotensin-aldosterone system Raises blood pressure Angiotensin II constricts arterioles Aldosterone causes kidneys to reabsorb sodium (causing water retention) Atrial natriuretic hormone (ANH) is antagonistic to aldosterone 34

35. Regulation of Blood Pressure and Volume 35 renin aldosterone Homeostasis (normal blood pressure) low blood Na + atrial natriuretic hormone (ANH) Kidneys excrete Na + and water in urine. Heart secretes atrial natriuretic hormone (ANH) into blood. Blood pressure lowers. Blood pressure rises. Kidneys secrete renin into blood. Kidneys reabsorb Na + and water from kidney tubules. Adrenal cortex secretes aldosterone into blood. angiotensin I and II high blood Na + Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

36. Addison Disease 36 a. b. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a: © Custom Medical Stock Photos; b: © NMSB/Custom Medical Stock Photos

37. Cushing Syndrome 37 (Both): Atlas of Pediatric Physical Diagnosis, Second Edition by Zitelli & Davis, 1992. Mosby-Wolfe Europe Limited, London, UK Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

38. Pancreas Made up of exocrine and endocrine tissue – Endocrine Portion of the Pancreas: Consists of pancreatic islets Produce and secrete – Insulin » Secreted during high blood glucose level » Stimulates uptake of glucose by cells – Glucagon » Secreted during low blood glucose level » Stimulates liver to break down glycogen – Exocrine Portion of the Pancreas: Secretes enzymes and buffers into intestine 38

39. Regulation of Blood Glucose Level 39 high blood glucose low blood glucose insulin glucagon Liver stores glucose from blood as glycogen. Pancreatic islet of Langerhans After eating, pancreas secretes insulin into blood. Muscle cells store glycogen and build protein. Adipose tissue uses glucose from blood to form fat. Homeostasis (normal blood glucose) Blood glucose level lowers. Before eating, pancreas secretes glucagon into blood. Liver breaks down glycogen to glucose. Glucose enters blood. Adipose tissue breaks down fat. Pancreatic islet of Langerhans Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Peter Arnold, Inc./Alamy

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41. Other Endocrine Glands Gonads – Testes Produce testosterone Secondary sex characteristics – Ovaries Produce estrogen and progesterone Reproduction Secondary sex characteristics 41

42. The Effects of Anabolic Steroid Use 42 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. deepening of voice in women severe acne balding in men and women; hair on face and chest in women breast enlargement in men and breast reduction in women liver dysfunction and cancer kidney disease and retention of fluids, called "steroid bloat" reduced testicular size, low sperm count, and impotency 'roid mania– delusions and hallucinations; depression upon withdrawal high blood cholesterol and atherosclerosis; high blood pressure and damage to heart in women, increased size of ovaries; cessation of ovulation and menstruation stunted growth in youngsters by pre- maturely halting fusion of the growth plates

43. Other Endocrine Glands Pineal Gland Produces melatonin Involved in Circadian rhythms Thymus Gland Secrete thymosins Aid in differentiation of lymphocytes Prostaglandins Produced within cells Not distributed in blood 43

44. Melatonin Production 44 6 P.M. 6 A.M. b. winter a. experimental c. summer Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © The McGraw-Hill Companies, Inc./ Evelyn Jo Johnson, photographer

45. Review Endocrine Glands Pheromones Steroid Hormones Peptide Hormones Hypothalamus and Pituitary Gland Other Endocrine Glands and Hormones Thyroid Parathyroid Adrenal Pancreas Gonads 45