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Chapter 26 Hormones and the Endocrine System PowerPoint Lectures for Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey Lecture by Edward J. Zalisko 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 Copyright © 2009 Pearson Education, Inc. THE NATURE OF CHEMICAL REGULATION 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 Copyright © 2009 Pearson Education, Inc. Secretory vesicles Blood vessel Target cell Endocrine cell Hormone molecules Blood vessel Neurosecretory cell Hormone molecules Target cell 26.1 Chemical signals coordinate body functions The endocrine system – Consists of all hormone-secreting cells – Works with nervous system to regulate body activities Copyright © 2009 Pearson Education, Inc. 26.1 Chemical signals coordinate body functions The nervous system also – Communicates – Regulates – Uses electrical signals via nerve cells 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 Copyright © 2009 Pearson Education, Inc. Nerve cell Nerve signals Neurotransmitter molecules Nerve cell 26.2 Hormones affect target cells by two main signaling mechanisms Hormone signaling involves three key events – Reception – Signal Transduction – Response 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 Copyright © 2009 Pearson Education, Inc. Water-soluble hormone (epinephrine) Target cell 1 Receptor protein Plasma membrane Water-soluble hormone (epinephrine) Target cell Relay molecules 1 Receptor protein 2 Plasma membrane Signal transduction pathway Water-soluble hormone (epinephrine) Target cell 1 Receptor protein 2 Plasma membrane Signal transduction pathway Relay molecules 3 Glycogen Glucose Cellular response (in this example, glycogen breakdown) 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 Copyright © 2009 Pearson Education, Inc. Lipid-soluble hormone (testosterone) Target cell Nucleus 1 Lipid-soluble hormone (testosterone) Target cell Nucleus 1 2 Receptor protein Lipid-soluble hormone (testosterone) Target cell Nucleus DNA 1 2 Receptor protein 3 Hormonereceptor complex Lipid-soluble hormone (testosterone) 1 Target cell 2 Receptor protein Nucleus 3 Hormonereceptor complex DNA 4 Transcription mRNA New protein Cellular response: activation of a gene and synthesis of new protein THE VERTEBRATE ENDOCRINE SYSTEM 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 Copyright © 2009 Pearson Education, Inc. 26.3 Overview: The vertebrate endocrine system consists of more than a dozen major glands Glands – Some are specialized for hormone secretion only – Some also do other jobs Copyright © 2009 Pearson Education, Inc. Hypothalamus Pineal gland Pituitary gland Thyroid gland Parathyroid glands Thymus Adrenal glands (atop kidneys) Pancreas Ovary (female) Testes (male) 26.3 Overview: The vertebrate endocrine system consists of more than a dozen major glands Hormones – Some have a very narrow range of targets and effects – Some have numerous effects on many kinds of target cells 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 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 Copyright © 2009 Pearson Education, Inc. Brain Hypothalamus Posterior pituitary Anterior pituitary (Bone) Hypothalamus Hormone Neurosecretory cell Posterior pituitary Blood vessel Oxytocin Anterior pituitary ADH Uterine muscles Kidney tubules Mammary glands 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 Copyright © 2009 Pearson Education, Inc. Neurosecretory cell Blood vessel Releasing hormones from hypothalamus Endocrine cells of the anterior pituitary Pituitary hormones TSH ACTH FSH and LH Prolactin (PRL) Growth hormone (GH) Thyroid Adrenal Testes or Mammary Entire body cortex ovaries glands (in mammals) Endorphins Pain receptors in the brain Hypothalamus Inhibition TRH Anterior pituitary TSH Thyroid Thyroxine Inhibition HORMONES AND HOMEOSTASIS Copyright © 2009 Pearson Education, Inc. 26.5 The thyroid regulates development and metabolism Thyroid gland hormones – Thyroxine (T4) and triiodothyronine (T3) – Regulate – Metabolism – Development – Negative feedback – Maintain homeostatic levels of T4 and T3 in the blood Copyright © 2009 Pearson Education, Inc. No inhibition Hypothalamus TRH Anterior pituitary No inhibition TSH No iodine Thyroid Thyroid grows to form goiter Insufficient T4 and T3 produced 26.5 The thyroid regulates development and metabolism Thyroid imbalance can cause disease – Hyperthyroidism – Too much T4 and T3 in the blood – Leads to high blood pressure, loss of weight, overheating, and irritability – Produces Graves’ disease – Hypothyroidism – Too little T4 and T3 in the blood – Leads to low blood pressure, overweight, often cold, lethargy 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 Copyright © 2009 Pearson Education, Inc. 8 7 Calcitonin Thyroid gland releases calcitonin Stimulates Reduces Ca2+ deposition Ca2+ uptake in bones in kidneys 9 6 Stimulus: Rising blood Ca2+ level (imbalance) Blood Ca2+ falls Ca2+ level Homeostasis: Normal blood calcium level (about 10 mg/100 mL) Ca2+ level Stimulus: Falling blood Ca2+ level (imbalance) 1 Blood Ca2+ rises 5 Parathyroid glands release parathyroid hormone (PTH) Stimulates Ca2+ release from bones 2 3 PTH Increases Active Ca2+ uptake vitamin D in kidneys Increases Ca2+ uptake in intestines 4 Parathyroid gland Ca2+ level Homeostasis: Normal blood calcium level (about 10 mg/100 mL) Ca2+ level Stimulus: Falling blood Ca2+ level (imbalance) 1 Blood Ca2+ rises 5 Parathyroid glands release parathyroid hormone (PTH) Stimulates Ca2+ release from bones 2 3 PTH Increases Active Ca2+ uptake vitamin D in kidneys Increases Ca2+ uptake in intestines 4 Parathyroid gland 8 7 Calcitonin Thyroid gland releases calcitonin Stimulates Reduces 2+ Ca deposition Ca2+ uptake in bones in kidneys 9 6 Stimulus: Rising blood Ca2+ level (imbalance) Blood Ca2+ falls Ca2+ level Homeostasis: Normal blood calcium level (about 10 mg/100 mL) Ca2+ level 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 Copyright © 2009 Pearson Education, Inc. Body cells take up more glucose Insulin 3 2 Beta cells of pancreas stimulated to release insulin into the blood 4 Blood glucose level declines to a set point; stimulus for insulin release diminishes Liver takes up glucose and stores it as glycogen 1 High blood glucose level Stimulus: Rising blood glucose level (e.g., after eating a carbohydrate-rich meal) Glucose level Homeostasis: Normal blood glucose level (about 90 mg/100 mL) Glucose level Stimulus: Declining blood glucose level (e.g., after skipping a meal) 5 Low blood glucose level Blood glucose level rises to set point; stimulus for glucagon release diminishes 6 Alpha cells of pancreas stimulated to release glucagon into the blood 8 Liver breaks down glycogen and releases glucose to the blood 7 Glucagon Insulin Body cells take up more glucose 3 2 Beta cells of pancreas stimulated to release insulin into the blood 4 Liver takes up glucose and stores it as glycogen 1 High blood glucose level Stimulus: Rising blood glucose level (e.g., after eating a carbohydrate-rich meal) Glucose level Homeostasis: Normal blood glucose level (about 90 mg/100 mL) Glucose level Blood glucose level declines to a set point; stimulus for insulin release diminishes Glucose level Homeostasis: Normal blood glucose level (about 90 mg/100 mL) Glucose level Stimulus: Declining blood glucose level (e.g., after skipping a meal) 5 Low blood glucose level Blood glucose level rises to set point; stimulus for glucagon release diminishes 6 Alpha cells of pancreas stimulated to release glucagon into the blood 8 Liver breaks down glycogen and releases glucose to the blood 7 Glucagon 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 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 Copyright © 2009 Pearson Education, Inc. Blood glucose (mg/100 mL) 400 350 300 Diabetic 250 200 150 Normal 100 50 0 0 1 2 1 2 4 3 Hours after glucose ingestion 5 26.9 The adrenal glands mobilize responses to stress Hormones from the adrenal glands help maintain homeostasis when the body is stressed 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 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 Copyright © 2009 Pearson Education, Inc. Adrenal gland Kidney Stress Adrenal medulla Adrenal cortex Nerve signals 1 Hypothalamus 3 Releasing hormone Anterior pituitary Nerve cell Spinal cord (cross section) 4 Nerve cell Blood vessel ACTH 5 Adrenal medulla 2 Epinephrine and norepinephrine Short-term stress response 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 Adrenal cortex ACTH Mineralocorticoids Glucocorticoids Long-term stress response Mineralocorticoids Glucocorticoids 1. Proteins and fats 1. Retention of broken down and sodium ions and converted to glucose, water by kidneys leading to increased 2. Increased blood blood glucose volume and blood 2. Immune system may pressure be suppressed Adrenal medulla Adrenal gland Adrenal cortex Kidney Nerve signals Stress 1 Hypothalamus 3 Releasing hormone Anterior pituitary Nerve cell Spinal cord (cross section) 4 Nerve cell Blood vessel ACTH 5 Adrenal cortex Adrenal medulla 2 Epinephrine and norepinephrine Short-term stress response ACTH Mineralocorticoids Glucocorticoids Long-term stress response Short-term stress response 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 Long-term stress response Mineralocorticoids Glucocorticoids 1. Proteins and fats 1. Retention of broken down and sodium ions and converted to glucose, water by kidneys leading to increased 2. Increased blood blood glucose volume and blood pressure 2. Immune system may be suppressed 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 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 Copyright © 2009 Pearson Education, Inc. 26.10 The gonads secrete sex hormones Androgens – Such as testosterone – Trigger the development of male characteristics 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 Copyright © 2009 Pearson Education, Inc. 26.11 EVOLUTION CONNECTION: A single hormone can perform a variety of functions in different animals Prolactin – Nonhuman mammals—stimulates nest building – Birds—regulates fat metabolism and reproduction – Amphibians—movement to water – Fish—migration between salt and fresh water Copyright © 2009 Pearson Education, Inc. Watersoluble hormone Receptor protein Lipidsoluble hormone Receptor protein Signal transduction pathway Hormonereceptor complex DNA mRNA Cellular response New protein Brain Posterior pituitary: Composed of nervous tissue; stores and secretes hormones made by hypothalamus Hypothalamus: Master control center of the endocrine system Anterior pituitary: Composed of endocrine tissue; controlled by hypothalamus; produces and secretes its own hormones 1. thyroxine 2. epinephrine 3. androgens a. b. c. d. 4. insulin 5. melatonin 6. FSH 7. PTH 8. ADH Pineal gland Testes Parathyroid gland Adrenal medulla Hypothalamus Pancreas Anterior pituitary Thyroid gland lowers blood glucose stimulates ovaries triggers fight-or-flight promotes male traits e. regulates metabolism f. related to daily rhythm g. raises blood calcium levels h. boosts water retention 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 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 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 Copyright © 2009 Pearson Education, Inc.