1. Chapter 45 Chemical Signals in Animals

2. The endocrine system and the nervous system act individually and together in regulating an animal’s physiology The nervous system –Conveys high-speed electrical signals along specialized cells called neurons The endocrine system, made up of endocrine glands –Secretes hormones that coordinate slower but longer- acting responses to stimuli

3. Overlap Between Endocrine and Nervous Regulation The endocrine and nervous systems –Often function together in maintaining homeostasis, development, and reproduction

4. Specialized nerve cells known as neurosecretory cells –Release neurohormones into the blood Both endocrine hormones and neurohormones –Function as long-distance regulators of many physiological processes

5. Control Pathways and Feedback Loops There are three types of hormonal control pathways PathwayExample Stimulus Low blood glucose Receptor protein Pancreas secretes glucagon ( ) Endocrine cell Blood vessel Liver Target effectors Response Pathway Example Stimulus Suckling Sensory neuron Hypothalamus/ posterior pituitary Neurosecretory cell Blood vessel Posterior pituitary secretes oxytocin ( ) Target effectors Smooth muscle in breast Response Milk release Pathway Example Stimulus Hypothalamic neurohormone released in response to neural and hormonal signals Sensory neuron Hypothalamus secretes prolactin- releasing hormone ( ) Neurosecretory cell Blood vessel Anterior pituitary secretes prolactin ( ) Endocrine cell Blood vessel Target effectors Response Mammary glands Milk production (c) Simple neuroendocrine pathway (b) Simple neurohormone pathway (a) Simple endocrine pathway Hypothalamus Glycogen breakdown, glucose release into blood Figure 45.2a–c

6. A common feature of control pathways –Is a feedback loop connecting the response to the initial stimulus Negative feedback –Regulates many hormonal pathways involved in homeostasis

7. Overview: The Body’s Long-Distance Regulators An animal hormone –Is a chemical signal that is secreted into the circulatory system and communicates regulatory messages within the body Hormones may reach all parts of the body –But only certain types of cells, target cells, are equipped to respond

8. Concept 45.2: Hormones and other chemical signals bind to target cell receptors, initiating pathways that culminate in specific cell responses Hormones convey information via the bloodstream –To target cells throughout the body

9. Three major classes of molecules function as hormones in vertebrates 1.Proteins and peptides 2.Amines derived from amino acids 3.Steroids

10. Signaling by any of these molecules involves three key events 1.Reception 2.Signal transduction 3.Response

11. Growth factors: proteins and polypeptides that stimulate cell proliferation Example: nerve growth factor (NGF) affects certain embryonic cells, developing white blood cells, and other kinds of cells 1. A variety of local regulators affect neighboring target cells Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

12. Paracrine Signaling by Local Regulators In a process called paracrine signaling –Various types of chemical signals elicit responses in nearby target cells

13. Local regulators have various functions and include –Neurotransmitters –Cytokines and growth factors –Nitric oxide –Prostaglandins

14. Nitric oxide (NO) –Though a gas, NO is an important local regulator. –When secreted by neurons, it acts as a neurotransmitter. –When secreted by white blood cells, it kills bacteria and cancer cells. –And when secreted by endothelial cells, it dilates the walls of blood vessels. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Prostaglandins (PGs): modified fatty acids. –PGs secreted by the placenta stimulate uterine contractions during childbirth. –Other PGs play a role in inflammation and the blood flow to the lungs.

16. Prostaglandins help regulate the aggregation of platelets –An early step in the formation of blood clots Figure 45.5

17. 2. Most chemical signals bind to plasma- membrane proteins, initiating signal- transduction pathways. Fig. 45.3a

19. Cell-Surface Receptors for Water- Soluble Hormones The receptors for most water-soluble hormones –Are embedded in the plasma membrane, projecting outward from the cell surface Figure 45.3a SECRETORY CELL Hormone molecule VIA BLOOD Signal receptor TARGET CELL Signal transduction pathway Cytoplasmic response Nuclear response NUCLEUS DNA OR (a) Receptor in plasma membrane

20. Different signal-transduction pathways in different cells can lead to different responses to the same signal. Fig. 45.4 The same hormone may have different effects on target cells that have –Different receptors for the hormone –Different proteins for carrying out the response –Different signal transduction pathways

21. The hormone epinephrine –Has multiple effects in mediating the body’s response to short-term stress Different receptors different cell responses Epinephrine  receptor Epinephrine  receptor Epinephrine  receptor Vessel constricts Vessel dilates Glycogen breaks down and glucose is released from cell (a) Intestinal blood vessel (b) Skeletal muscle blood vessel (c) Liver cell Different intracellular proteins different cell responses Glycogen deposits Figure 45.4a–c

22. Signal- transduction pathways allow for small amounts of a hormone to have a large effect. Cascade effect results in amplification Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig.11.16

23. Examples: estrogen, progesterone, vitamin D, NO. –Usually, the intracellular receptor activated by a hormone is a transcription factor. 3. Steroid hormones, thyroid hormones, and some local regulators enter target cells and bind to intracellular receptors Fig. 45.3b

24. Intracellular Receptors for Lipid- Soluble Hormones Steroids, thyroid hormones, and the hormonal form of vitamin D –Enter target cells and bind to specific protein receptors in the cytoplasm or nucleus

27.  Tropic hormones target other endocrine glands and are important to understanding chemical coordination. Humans have nine endocrine glands. Introduction Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 45.5 Memorize chart on p899!!!

28. Concept 45.3: The hypothalamus and pituitary integrate many functions of the vertebrate endocrine system The hypothalamus and the pituitary gland –Control much of the endocrine system

29. Relation Between the Hypothalamus and Pituitary Gland The hypothalamus, a region of the lower brain –Contains different sets of neurosecretory cells

30. Figure 45.7 Hypothalamus Neurosecretory cells of the hypothalamus Axon Anterior pituitary Posterior pituitary HORMONE ADH Oxytocin TARGET Kidney tubules Mammary glands, uterine muscles Some of these cells produce direct-acting hormones –That are stored in and released from the posterior pituitary, or neurohypophysis

32. Posterior Pituitary Hormones The two hormones released from the posterior pituitary –Act directly on nonendocrine tissues

33. Oxytocin –Induces uterine contractions and milk ejection Antidiuretic hormone (ADH) –Enhances water reabsorption in the kidneys

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36. Fat metabolism and reproduction in birds Delays metamorphosis in amphibians Regulates larval growth and salt balance in fish

37. Table 45.1 (continued)

38. Anterior Pituitary Hormones The anterior pituitary –Produces both tropic and nontropic hormones

39. Tropic Hormones The four strictly tropic hormones are –Follicle-stimulating hormone (FSH) –Luteinizing hormone (LH) –Thyroid-stimulating hormone (TSH) –Adrenocorticotropic hormone (ACTH) Each tropic hormone acts on its target endocrine tissue –To stimulate release of hormone(s) with direct metabolic or developmental effects

40. Nontropic Hormones The nontropic hormones produced by the anterior pituitary include 1.Prolactin 2.Melanocyte-stimulating hormone (MSH)  -endorphin

41. Prolactin stimulates lactation in mammals –But has diverse effects in different vertebrates MSH influences skin pigmentation in some vertebrates –And fat metabolism in mammals Endorphins –Inhibit the sensation of pain

42. Growth Hormone Growth hormone (GH) –Promotes growth directly and has diverse metabolic effects –Stimulates the production of growth factors by other tissues

43. Growth hormones can increase yield and in cows, increase milk production

45. Concept 45.4: Nonpituitary hormones help regulate metabolism, homeostasis, development, and behavior Many nonpituitary hormones –Regulate various functions in the body

46. Thyroid Hormones The thyroid gland –Consists of two lobes located on the ventral surface of the trachea –Produces two iodine-containing hormones, triiodothyronine (T 3 ) and thyroxine (T 4 )

47. The hypothalamus and anterior pituitary –Control the secretion of thyroid hormones through two negative feedback loops Hypothalamus Anterior pituitary TSH Thyroid T3T3 T4T4 + Figure 45.9

48. The thyroid hormones –Play crucial roles in stimulating metabolism and influencing development and maturation

49. Anti-Diuretic Hormone

50. The thyroid gland of mammals consists of two lobes located on the ventral surface of the trachea. –Triiodothyronine (T 3 ) and thyroxine (T 4 ): amines. –Stimulates and maintain metabolic processes. –Secretion regulated by TSH hormones. 3. Thyroid hormones function in develop- ment, bioenergetics, and homeostasis Fig. 45.8

52.  Hyperthyroidism is the excessive secretion of thyroid hormones, exhibited by high body temperature, profuse sweating, weight loss, irritability, high blood pressure.  An insufficient amount of thyroid hormones is known as hypothyroidism.  Infants: cretinism.  Adults: weight gain, lethargy, cold intolerance.  Goiter: often associated with iodine deficiency. Exophthalmia Graves’ Disease Exophthalmia Graves’ Disease Goiter

53.  Calcitonin: a peptide.  Lowers blood calcium levels.  Secretion regulated by calcium in blood. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

54. The four parathyroid glands are embedded in the surface of the thyroid gland. PTH raises blood calcium levels PTH takes Ca ++ from bones, causes more absorption form intestines and more reabsorption form the kidneys. Underfunction can result in TETANY. 4. Parathyroid hormone and calcitonin regulate blood calcium level Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

55. tetany

59. Insulin

60. CCK

61. The adrenal glands are located adjacent to the kidneys. –The adrenal cortex is the outer portion. –The adrenal medulla is the inner portion. 6. The adrenal medulla and adrenal cortex help the body manage stress Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

63. –Adrenal medulla. Developmentally and functionally related to the nervous system. Epinephrine (adrenaline) and norepinephrine (noradrenaline). –Catecholamines: amines synthesized from tyrosine. –Secretion regulated by the nervous system in response to stress. –Raises blood glucose level and blood fatty acid level. –Increase metabolic activities. –Increases heart rate and stroke volume and dilates bronchioles. –Shunts blood away from skin, digestive organs, and kidneys, and increases blood flow to heart, brain, and skeletal muscle. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

65. Stress Hormones from the Adrenal Cortex Hormones from the adrenal cortex –Also function in the body’s response to stress –Fall into three classes of steroid hormones

66. Glucocorticoids. –Raises blood glucose level. –Secretion regulated by ACTH (negative feedback). –Abnormally high doses are administered as medication to suppress the inflammation response. Adrenal cortex reacts to stress. Secretion of corticosteroids is regulated by the nervous system in response to stress. Mineralocorticoids (example: aldosterone, which affects salt and water balance). –Promotes reabsorption of Na + and excretion of K + in kidneys. –Secretion regulated by K + in blood. Sex hormones –Are produced in small amounts

68. ABC NEWS// 4/5/01 Marriage and Hormones Scientists Say the Body’s Hormones Detect Divorce First But when the researchers took a close look at the failed marriages, they were in for a surprise. Although such things as aggression and a negative attitude are generally thought of as the best predictors of divorce, the researchers found a more tantalizing clue in the blood samples collected more than a decade earlier. Those same three hormones — epinephrine, norepinephrine and ACTH — were "consistently and significantly elevated in the couples" who later divorced, Kiecolt-Glaser says. These are "stress hormones," the "fight or flight" chemical messengers that are supposed to tell us whether to hang around and duke it out or run for cover. "If those hormones stay up, you're probably going to have higher blood pressure, higher heart rate, and it's not good for your body," she says. The elevated hormone level didn't just appear in the blood drawn during the discussion of marital problems, she adds, it was present in later samples, even those drawn while the participants were asleep. ABC NEWS// 4/5/01 Marriage and Hormones Scientists Say the Body’s Hormones Detect Divorce First But when the researchers took a close look at the failed marriages, they were in for a surprise. Although such things as aggression and a negative attitude are generally thought of as the best predictors of divorce, the researchers found a more tantalizing clue in the blood samples collected more than a decade earlier. Those same three hormones — epinephrine, norepinephrine and ACTH — were "consistently and significantly elevated in the couples" who later divorced, Kiecolt-Glaser says. These are "stress hormones," the "fight or flight" chemical messengers that are supposed to tell us whether to hang around and duke it out or run for cover. "If those hormones stay up, you're probably going to have higher blood pressure, higher heart rate, and it's not good for your body," she says. The elevated hormone level didn't just appear in the blood drawn during the discussion of marital problems, she adds, it was present in later samples, even those drawn while the participants were asleep.

70. Testes. –Androgens (example: testosterone): steroids. Supports sperm formation. Promote development and maintenance of male sex characteristics. Secretion regulated by FSH and LH. 7. Gonadal steroids regulate growth, development, reproductive cycles, and sexual behavior Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

71. Ovaries secrete estrogens and progesterone. –Estrogens: steroids. Stimulate uterine lining growth. Promote development and maintenance of female sex characteristics. Secretion regulated by FSH and LH. –Progestins (example: progesterone): steroids. Promotes uterine lining growth. Secretion regulated by FSH and LH.

72. Gonadal Sex Hormones The gonads—testes and ovaries –Produce most of the body’s sex hormones: androgens, estrogens, and progestins

73. The testes primarily synthesize androgens, the main one being testosterone –Which stimulate the development and maintenance of the male reproductive system

74. Testosterone causes an increase in muscle and bone mass –And is often taken as a supplement to cause muscle growth, which carries many health risks Figure 45.14 Mr. Chee - before he started working out

75. Estrogens, the most important of which is estradiol –Are responsible for the maintenance of the female reproductive system and the development of female secondary sex characteristics In mammals, progestins, which include progesterone –Are primarily involved in preparing and maintaining the uterus

76. Melatonin and Biorhythms The pineal gland, located within the brain –Secretes melatonin

77. Release of melatonin –Is controlled by light/dark cycles The primary functions of melatonin –Appear to be related to biological rhythms associated with reproduction

78. Insect metamorphosis –Is regulated by hormones Figure 45.1

80. Concept 45.5: Invertebrate regulatory systems also involve endocrine and nervous system interactions Diverse hormones –Regulate different aspects of homeostasis in invertebrates

81. In insects –Molting and development are controlled by three main hormones Brain Neurosecretory cells Corpus cardiacum Corpus allatum EARLY LARVA LATER LARVA PUPA ADULT Prothoracic gland Ecdysone Brain hormone (BH) Juvenile hormone (JH) Low JH Neurosecretory cells in the brain produce brain hormone (BH), which is stored in the corpora cardiaca (singular, corpus cardiacum) until release. 1 BH signals its main target organ, the prothoracic gland, to produce the hormone ecdysone. 2 Ecdysone secretion from the prothoracic gland is episodic, with each release stimulating a molt. 3 Juvenile hormone (JH), secreted by the corpora allata, determines the result of the molt. At relatively high concen- trations of JH, ecdysone-stimulated molting produces another larval stage. JH suppresses metamorphosis. But when levels of JH fall below a certain concentration, a pupa forms at the next ecdysone-induced molt. The adult insect emerges from the pupa. 4 Figure 45.15

82. Brain hormone –Is produced by neurosecretory cells –Stimulates the release of ecdysone from the prothoracic glands

83. Ecdysone –Promotes molting and the development of adult characteristics Juvenile hormone –Promotes the retention of larval characteristics