1. Copyright © 2009 Pearson Education, Inc. THE NATURE OF CHEMICAL REGULATION

2. Copyright © 2009 Pearson Education, Inc. 26.1 Chemical signals coordinate body functions  The endocrine system –Consists of all hormone-secreting cells –Works with nervous system to regulate body activities

3. Copyright © 2009 Pearson Education, Inc. 26.1 Chemical signals coordinate body functions  The nervous system also –Communicates –Regulates –Uses electrical signals via nerve cells

4. Copyright © 2009 Pearson Education, Inc. 26.1 Chemical signals coordinate body functions  Comparing the endocrine and nervous systems –Nervous system reacts faster –Endocrine system responses last longer

5. Copyright © 2009 Pearson Education, Inc. 26.1 Chemical signals coordinate body functions  Hormones –Chemical signals –Usually carried in the blood –Cause specific changes in target cells –Secreted by –Endocrine glands –Neurosecretory cells

6. Secretory vesicles Target cell Blood vessel Hormone molecules Endocrine cell

7. Hormone molecules Target cell Blood vessel Neurosecretory cell

8. Neurotransmitter molecules Nerve cell Nerve cell Nerve signals

9. Copyright © 2009 Pearson Education, Inc. 26.2 Hormones affect target cells by two main signaling mechanisms  Hormone signaling involves three key events –Reception –Signal Transduction –Response

10. Copyright © 2009 Pearson Education, Inc. 26.2 Hormones affect target cells by two main signaling mechanisms  Amino-acid-derived hormones –Are water-soluble –Include proteins, peptides, and amines –Bind to plasma-membrane receptors on target cells –Initiate a signal transduction pathway Animation: Water-Soluble Hormone

11. Plasma membrane Receptor protein Water-soluble hormone (epinephrine) 1 Target cell

12. Plasma membrane Receptor protein Water-soluble hormone (epinephrine) 2 Signal transduction pathway Relay molecules 1 Target cell

13. Plasma membrane Receptor protein Target cell Water-soluble hormone (epinephrine) 1 2 Signal transduction pathway Relay molecules Glycogen Glucose Cellular response (in this example, glycogen breakdown) 3

14. Copyright © 2009 Pearson Education, Inc. 26.2 Hormones affect target cells by two main signaling mechanisms  Steroid hormones –Nonpolar lipids made from cholesterol –Can diffuse through plasma membranes –Bind to a receptor protein in the cytoplasm or nucleus –Hormone-receptor complex carries out the transduction of the hormonal signal Animation: Lipid-Soluble Hormone

15. Lipid-soluble hormone (testosterone) Target cell Nucleus 1

16. Lipid-soluble hormone (testosterone) 1 Target cell Nucleus Receptor protein 2

17. Lipid-soluble hormone (testosterone) 1 Target cell Nucleus Receptor protein 2 DNA Hormone- receptor complex 3

18. Lipid-soluble hormone (testosterone) 1 Target cell Nucleus Receptor protein 2 DNA Hormone- receptor complex 3 mRNA Transcription New protein Cellular response: activation of a gene and synthesis of new protein 4

19. New protein Cellular response mRNA DNA Hormone- receptor complex Receptor protein Lipid- soluble hormone Water- soluble hormone Receptor protein Signal transduction pathway

20. Copyright © 2009 Pearson Education, Inc. THE VERTEBRATE ENDOCRINE SYSTEM

21. Copyright © 2009 Pearson Education, Inc. 26.3 Overview: The vertebrate endocrine system consists of more than a dozen major glands  The vertebrate endocrine system –Consists of more than a dozen glands –Secretes more than 50 hormones

22. Copyright © 2009 Pearson Education, Inc.  Glands –Some are specialized for hormone secretion only –Some also do other jobs 26.3 Overview: The vertebrate endocrine system consists of more than a dozen major glands

23. Hypothalamus Parathyroid glands Pineal gland Pituitary gland Thyroid gland Thymus Adrenal glands (atop kidneys) Pancreas Ovary (female) Testes (male)

24. Copyright © 2009 Pearson Education, Inc.  Hormones –Some have a very narrow range of targets and effects –Some have numerous effects on many kinds of target cells 26.3 Overview: The vertebrate endocrine system consists of more than a dozen major glands

26. Copyright © 2009 Pearson Education, Inc. 26.4 The hypothalamus, which is closely tied to the pituitary, connects the nervous and endocrine systems  The hypothalamus –Blurs the distinction between endocrine and nervous systems –Receives input from nerves about body conditions –Responds by sending out appropriate nervous or endocrine signals –Uses the pituitary gland to exert master control over the endocrine system

27. Copyright © 2009 Pearson Education, Inc. 26.4 The hypothalamus, which is closely tied to the pituitary, connects the nervous and endocrine systems  The pituitary gland consists of two parts –Posterior pituitary –Composed of nervous tissue –Stores and secretes oxytocin and ADH

28. Brain Hypothalamus Posterior pituitary Anterior pituitary (Bone)

29. Hypothalamus Posterior pituitary Anterior pituitary Hormone Neurosecretory cell Blood vessel Oxytocin ADH Kidney tubules Uterine muscles Mammary glands

30. Copyright © 2009 Pearson Education, Inc. 26.4 The hypothalamus, which is closely tied to the pituitary, connects the nervous and endocrine systems  Anterior pituitary –Synthesizes and secretes hormones that control the activity of other glands –Is controlled by the hypothalamus –Releasing hormones stimulate the anterior pituitary –Inhibiting hormones inhibit the anterior pituitary

31. Endocrine cells of the anterior pituitary Pituitary hormones Releasing hormones from hypothalamus Neurosecretory cell Blood vessel FSH and LH TSH ACTH Prolactin (PRL) Growth hormone (GH) Endorphins Thyroid Adrenal cortex Testes or ovaries Mammary glands (in mammals) Entire body Pain receptors in the brain

32. Copyright © 2009 Pearson Education, Inc. HORMONES AND HOMEOSTASIS

33. Copyright © 2009 Pearson Education, Inc. 26.5 The thyroid regulates development and metabolism  Thyroid gland hormones –Thyroxine (T 4 ) and triiodothyronine (T 3 ) –Regulate –Metabolism –Development –Negative feedback –Maintain homeostatic levels of T 4 and T 3 in the blood

34. TSH TRH Hypothalamus Anterior pituitary Thyroid Thyroxine Inhibition

35. Copyright © 2009 Pearson Education, Inc. 26.5 The thyroid regulates development and metabolism  Thyroid imbalance can cause disease –Hyperthyroidism –Too much T 4 and T 3 in the blood –Leads to high blood pressure, loss of weight, overheating, and irritability –Produces Graves’ disease –Hypothyroidism –Too little T 4 and T 3 in the blood –Leads to low blood pressure, overweight, often cold, lethargy

37. No inhibition No iodine No inhibition Insufficient T 4 and T 3 produced Hypothalamus Anterior pituitary Thyroid Thyroid grows to form goiter TRH TSH

38. Copyright © 2009 Pearson Education, Inc. 26.6 Hormones from the thyroid and parathyroids maintain calcium homeostasis  Blood calcium level is regulated by a tightly balanced antagonism between –Calcitonin from the thyroid –Parathyroid hormone (PTH) from the parathyroid glands

39. Calcitonin 8 7 6 5 4 3 2 1 9 Thyroid gland releases calcitonin Stimulus: Rising blood Ca 2 + level (imbalance) Blood Ca 2 + rises Ca 2 + level Ca 2 + level Homeostasis: Normal blood calcium level (about 10 mg/100 mL) Stimulus: Falling blood Ca 2 + level (imbalance) Blood Ca 2 + falls Stimulates Ca 2 + deposition in bones Reduces Ca 2 + uptake in kidneys PTH Stimulates Ca 2 + release from bones Increases Ca 2 + uptake in intestines Active vitamin D Increases Ca 2 + uptake in kidneys Parathyroid glands release parathyroid hormone (PTH) Parathyroid gland

40. Copyright © 2009 Pearson Education, Inc. 26.7 Pancreatic hormones regulate blood glucose levels  The pancreas secretes two hormones that control blood glucose –Insulin—signals cells to use and store glucose –Glucagon—causes cells to release stored glucose into the blood

41. Insulin 4 Beta cells of pancreas stimulated to release insulin into the blood Glucose level Homeostasis: Normal blood glucose level (about 90 mg/100 mL) Glucose level Glucagon Low blood glucose level High blood glucose level Body cells take up more glucose Blood glucose level declines to a set point; stimulus for insulin release diminishes Liver takes up glucose and stores it as glycogen Alpha cells of pancreas stimulated to release glucagon into the blood Stimulus: Declining blood glucose level (e.g., after skipping a meal) Stimulus: Rising blood glucose level (e.g., after eating a carbohydrate-rich meal) Blood glucose level rises to set point; stimulus for glucagon release diminishes Liver breaks down glycogen and releases glucose to the blood 7 6 1 2 5 8 3

42. Copyright © 2009 Pearson Education, Inc. 26.8 CONNECTION: Diabetes is a common endocrine disorder  Diabetes mellitus –Results from –A lack of insulin or –A failure of cells to respond to it –Affects about 21 million Americans

43. Copyright © 2009 Pearson Education, Inc. 26.8 CONNECTION: Diabetes is a common endocrine disorder  Two common types of diabetes mellitus –Type 1 (insulin-dependent) –Autoimmune disease –Insulin-producing cells destroyed –Type 2 (non-insulin-dependent) –Deficiency of insulin –More commonly, reduced response to insulin –More than 90% of diabetics are type 2 –Associated with being overweight and underactive

44. Blood glucose (mg/100 mL) Hours after glucose ingestion Normal 400 Diabetic 300 250 200 150 100 50 0 0 350 1 2 3 4 5 1 2

45. Copyright © 2009 Pearson Education, Inc. 26.9 The adrenal glands mobilize responses to stress  Hormones from the adrenal glands help maintain homeostasis when the body is stressed

46. Copyright © 2009 Pearson Education, Inc. 26.9 The adrenal glands mobilize responses to stress  Nerve signals from the hypothalamus stimulate the adrenal medulla to secrete –Epinephrine –Norepinephrine  These hormones quickly trigger the fight-or-flight responses

47. Copyright © 2009 Pearson Education, Inc. 26.9 The adrenal glands mobilize responses to stress  Adrenocorticotropic hormone (ACTH) from the pituitary causes the adrenal cortex to secrete –Glucocorticoids –Mineralocorticoids  These hormones –Boost blood pressure –Boost energy in response to long-term stress

48. Hypothalamus Stress Releasing hormone Blood vessel Anterior pituitary Adrenal cortex ACTH Nerve cell Nerve cell Adrenal medulla 3 4 5 2 Nerve signals Adrenal medulla Adrenal gland Adrenal cortex Kidney Spinal cord (cross section) Epinephrine and norepinephrine Mineralocorticoids Glucocorticoids ACTH 1 Long-term stress response Short-term stress response

49. 1. Glycogen broken down to glucose; increased blood glucose 2. Increased blood pressure 3. Increased breathing rate 4. Increased metabolic rate 5. Change in blood-flow patterns, leading to increased alertness and decreased digestive and kidney activity

50. Long-term stress response MineralocorticoidsGlucocorticoids 2. Increased blood volume and blood pressure 1. Retention of sodium ions and water by kidneys 2. Immune system may be suppressed 1. Proteins and fats broken down and converted to glucose, leading to increased blood glucose

51. Copyright © 2009 Pearson Education, Inc. 26.10 The gonads secrete sex hormones  Steroid sex hormones –Include estrogens, progestins, and androgens –Produced by the gonads in response to signals from –Hypothalamus –Pituitary

52. Copyright © 2009 Pearson Education, Inc. 26.10 The gonads secrete sex hormones  Estrogens and progestins –Stimulate the development of female characteristics –Maintain the female reproductive system

53. Copyright © 2009 Pearson Education, Inc. 26.10 The gonads secrete sex hormones  Androgens –Such as testosterone –Trigger the development of male characteristics

55. Copyright © 2009 Pearson Education, Inc. 26.11 EVOLUTION CONNECTION: A single hormone can perform a variety of functions in different animals  Prolactin in humans –Stimulates mammary glands to grow and produce milk during late pregnancy –Suckling by a newborn stimulates further release of prolactin –High prolactin during nursing inhibits ovulation

57. Copyright © 2009 Pearson Education, Inc.  Prolactin –Nonhuman mammals—stimulates nest building –Birds—regulates fat metabolism and reproduction –Amphibians—movement to water –Fish—migration between salt and fresh water 26.11 EVOLUTION CONNECTION: A single hormone can perform a variety of functions in different animals

58. Copyright © 2009 Pearson Education, Inc. Introduction: Gender Benders  Endocrine disruptors –Environmental pollutants –Interfere with the action of hormones –Some are estrogen mimics in the environment that may produce –Demasculinized male alligators –Bass with male and female characteristics –Decrease in size and functioning of polar bear genitalia

62. Copyright © 2009 Pearson Education, Inc. You should now be able to 1.Explain how endocrine disruptors are causing environmental problems 2.Compare the mechanisms and functions of the endocrine and nervous systems 3.Distinguish between the two major classes of vertebrate hormones 4.Describe the different types and functions of vertebrate endocrine organs

63. Copyright © 2009 Pearson Education, Inc. You should now be able to 5.Describe the interrelationships between the hypothalamus and pituitary glands 6.Describe the functions of the thyroid and parathyroid glands 7.Explain how insulin and glucagon manage blood glucose levels 8.Describe the causes and symptoms of types 1 and 2 diabetes

64. Copyright © 2009 Pearson Education, Inc. You should now be able to 9.Compare the functions of the adrenal gland hormones 10.Describe the three major types of sex hormones and their functions 11.Describe the diverse functions of prolactin in vertebrate groups

65. Posterior pituitary: Composed of nervous tissue; stores and secretes hormones made by hypothalamus Brain Hypothalamus: Master control center of the endocrine system Anterior pituitary: Composed of endocrine tissue; controlled by hypothalamus; produces and secretes its own hormones

66. Pineal gland e. regulates metabolism f. related to daily rhythm g. raises blood calcium levels h. boosts water retention Parathyroid gland Hypothalamus a. lowers blood glucose b. stimulates ovaries c. triggers fight-or-flight d. promotes male traits Anterior pituitary Testes Adrenal medulla Pancreas Thyroid gland 4. insulin 5. melatonin 6. FSH 1. thyroxine 2. epinephrine 3. androgens 7. PTH 8. ADH