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  • 1. Chapter 45 Hormones and the Endocrine System
  • 2. Overview: The Body’s Long-Distance Regulators
    • Las hormonas animales son se ñales químicas que son secretadas al sistema circulatorio y se encargan de llevar mensajes regulatorios dentro del cuerpo
    • Las hormonas llegan a todas las partes del cuerpo, pero solo responden las c élulas blanco
      • Tienen receptores espec í ficos
  • 3.
    • La metamorfosis de los insectos est á regulada por hormonas
  • 4.  
  • 5. Concept 45.1: The endocrine system and the nervous system act individually and together in regulating an animal’s physiology
    • Los animales tienen dos sistemas de comunicaci ón y regulación interna: el sistema nervioso y el sistema endocrino
  • 6.
    • El sistema nervioso lleva se ñales eléctricas de alta velocidad a trav és de células e specializadas llamadas neuronas
    • El sistema endocrino secreta hormonas que coordinan respuestas m ás lentas pero m ás duraderas
  • 7. Overlap Between Endocrine and Nervous Regulation
    • Ambos sistemas trabajan juntos para mantener la homeostasis, el desarrollo, y la reproducci ó n
    • C élulas nerviosas es pecializadas llamadas c élulas neurosecretoras liberan neurohormonas a la sangre
    • Tanto las hormonas endocrinas como las neurohormonas trabajan como reguladores de larga distancia de muchos procesos fisiol ógicos
  • 8. Control Pathways and Feedback Loops
    • Hay tres tipos de trayectos de control hormonal: endocrino, neurohormonal, y neuroendocrino
    • Una caracter ística común e s un “feedback loop” que conecta la respuesta al est ímulo inicial
    • La retroalimentaci ón negativa regula muchos de los trayectos hormonales importantes en la homeostasis
  • 9. LE 45-2a Target effectors Response Simple endocrine pathway Glycogen breakdown, glucose release into blood Liver Blood vessel Pancreas secretes glucagon ( ) Endocrine cell Low blood glucose Receptor protein Stimulus Pathway Example
  • 10. LE 45-2b Target effectors Response Simple neurohormone pathway Stimulus Pathway Example Suckling Milk release Smooth muscle in breast Neurosecretory cell Blood vessel Posterior pituitary secretes oxytocin ( ) Hypothalamus/ posterior pituitary Sensory neuron
  • 11. LE 45-2c Target effectors Response Simple neuroendocrine pathway Stimulus Pathway Example Milk production Blood vessel Hypothalamus Sensory neuron Mammary glands Endocrine cell Blood vessel Anterior pituitary secretes prolactin ( ) Hypothalamus secretes prolactin- releasing hormone ( ) Neurosecretory cell Hypothalamic neurohormone released in response to neural and hormonal signals
  • 12. Concept 45.2: Hormones and other chemical signals bind to target cell receptors, initiating pathways that culminate in specific cell responses
    • Hormonas llevan la informaci ó n via la sangre hacia las c élulas blanco a trav és del cuerpo
    • Tres clases de mol é culas trabajan como hormonas en los vertebrados:
      • Prote í nas y p é ptidos
      • Aminas derivadas de amino á cidos
      • Esteroides
  • 13.
    • Signaling by any of these hormones involves three key events:
      • Reception
      • Signal transduction
      • Response
  • 14. 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
    Animation: Water-Soluble Hormone
  • 15. LE 45-3 SECRETORY CELL Hormone molecule Signal receptor VIA BLOOD VIA BLOOD TARGET CELL TARGET CELL Signal transduction pathway OR Cytoplasmic response DNA NUCLEUS Nuclear response Receptor in plasma membrane Receptor in cell nucleus DNA NUCLEUS mRNA Synthesis of specific proteins Signal transduction and response Signal receptor Hormone molecule SECRETORY CELL
  • 16.
    • Binding of a hormone to its receptor initiates a signal transduction pathway leading to responses in the cytoplasm or a change in gene expression
    • The same hormone may have different effects on target cells that have
      • Different receptors for the hormone
      • Different signal transduction pathways
      • Different proteins for carrying out the response
  • 17.
    • The hormone epinephrine has multiple effects in mediating the body’s response to short-term stress
  • 18. LE 45-4 Different receptors different cell responses Epinephrine  receptor Epinephrine  receptor Epinephrine  receptor Vessel constricts Vessel dilates Intestinal blood vessel Skeletal muscle blood vessel Liver cell Different intracellular proteins different cell responses Glycogen deposits Glycogen breaks down and glucose is released from cell
  • 19. Intracellular Receptors for Lipid-Soluble Hormones
    • Steroids, thyroid hormones, and the hormonal form of vitamin D enter target cells and bind to protein receptors in the cytoplasm or nucleus
    • Protein-receptor complexes then act as transcription factors in the nucleus, regulating transcription of specific genes
    Animation: Lipid-Soluble Hormone
  • 20. Paracrine Signaling by Local Regulators
    • In paracrine signaling, nonhormonal chemical signals called local regulators elicit responses in nearby target cells (la respuesta es m ás rápida)
    • Types of local regulators:
      • Neurotransmitters (derivados de aa)
      • Cytokines (respuesta inmunol ógica) and growth factors (estimulan proliferaci ón celular y diferenciación)
      • Nitric oxide (si O 2 baja,
      • Prostaglandins
  • 21.
    • Prostaglandins help regulate aggregation of platelets, an early step in formation of blood clots
  • 22.  
  • 23.
    • Aspirin (known chemically as acetyl salicylic acid and often abbreviated as ASA) belongs to a class of medications called nonsteroidal anti-inflammatory drugs or NSAIDs. Aspirin and other NSAIDs, for example, ibuprofen (Motrin, Advil) and naproxen (Aleve), are widely used to treat fever, pain, and inflammatory conditions such as arthritis , tendonitis, and bursitis . In addition to its effects on fever, pain, and inflammation , aspirin also has an important inhibitory effect on platelets in the blood. This antiplatelet effect is used to prevent the platelets from initiating the formation of blood clots inside arteries, particularly in individuals who have atherosclerosis or are otherwise prone to develop blood clots in their arteries.
  • 24.
    • Aspirin prevents blood from clotting by blocking the production of thromboxane A-2, a chemical that platelets produce that causes them to clump. Aspirin accomplishes this by inhibiting the enzyme cyclo-oxygenase-1 ( COX-1 ) that produces thromboxane A-2. While other NSAIDs also inhibit the COX-1 enzyme, aspirin is the preferred NSAID for use as an antiplatelet agent because its inhibition of the COX-1 enzyme lasts much longer than the other NSAIDs. Thus, aspirin ユ s antiplatelet effect lasts for days while the other NSAIDs ユ antiplatelet effects last for only hours.
  • 25.
    • Aspirin will inhibit the enzyme cyclo-oxygenase and will inhibit the prostaglandin-like substance, thromboxane A2 which in turn will increase the adhesion of platelets and cause a vascular blood clot, especially in a coronary artery.
  • 26.
    • aspirin inhibits the formation of chemicals called "prostaglandins" by blocking an essential enzyme needed for their formation. Among the many properties of prostaglandins is their ability to promote blood cells to stick together. Thus, by blocking the formation of prostaglandins, aspirin decreases the likelihood of blood clots forming in your blood vessels.Since a large number of heart attacks and strokes are directly caused by small, spontaneously forming blood clots, the ability of aspirin to prevent the formation of these small clots means that heart attacks and strokes become less likely.
  • 27.
    • The hypothalamus and the pituitary gland control much of the endocrine system
    Concept 45.3: The hypothalamus and pituitary integrate many functions of the vertebrate endocrine system
  • 28.  
  • 29.  
  • 30. LE 45-6 Testis (male) Ovary (female) Adrenal glands Pancreas Parathyroid glands Thyroid gland Pituitary gland Pineal gland Hypothalamus
  • 31. Relation Between the Hypothalamus and Pituitary Gland
    • The hypothalamus, a region of the lower brain, contains neurosecretory cells
    • The posterior pituitary, or neurohypophysis, is an extension of the hypothalamus
    • Hormonal secretions from neurosecretory cells are stored in or regulate the pituitary gland
  • 32.  
  • 33. LE 45-7 Mammary glands, uterine muscles Hypothalamus Kidney tubules Oxytocin HORMONE TARGET ADH Posterior pituitary Neurosecretory cells of the hypothalamus Axon Anterior pituitary
  • 34.
    • Other hypothalamic cells produce tropic hormones, hormones that regulate endocrine organs
    • Tropic hormones are secreted into the blood and transported to the anterior pituitary, or adenohypophysis
    • The tropic hormones of the hypothalamus control release of hormones from the anterior pituitary
  • 35. LE 45-8 Neurosecretory cells of the hypothalamus Endocrine cells of the anterior pituitary Portal vessels Pituitary hormones (blue dots) Pain receptors in the brain Endorphin Growth hormone Bones Liver MSH Melanocytes Prolactin Mammary glands ACTH Adrenal cortex TSH Thyroid Testes or ovaries FSH and LH TARGET HORMONE Hypothalamic releasing hormones (red dots) Tropic Effects Only FSH, follicle-stimulating hormone LH, luteinizing hormone TSH, thyroid-stimulating hormone ACTH, adrenocorticotropic hormone Nontropic Effects Only Prolactin MSH, melanocyte-stimulating hormone Endorphin Nontropic and Tropic Effects Growth hormone
  • 36. Posterior Pituitary Hormones
    • The two hormones released from the posterior pituitary act directly on nonendocrine tissues
    • Oxytocin induces uterine contractions and milk ejection
    • Antidiuretic hormone (ADH) enhances water reabsorption in the kidneys
  • 37. Anterior Pituitary Hormones
    • The anterior pituitary produces both tropic and nontropic hormones
  • 38. 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
  • 39. Nontropic Hormones
    • Nontropic hormones produced by the anterior pituitary:
      • Prolactin
      • Melanocyte-stimulating hormone (MSH)
      •  -endorphin
  • 40.
    • 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 pain
  • 41. Growth Hormone
    • Growth hormone (GH) has tropic and nontropic actions
    • It promotes growth directly and has diverse metabolic effects
    • It stimulates production of growth factors
  • 42. Concept 45.4: Nonpituitary hormones help regulate metabolism, homeostasis, development, and behavior
    • Many nonpituitary hormones regulate various functions in the body
  • 43. Thyroid Hormones
    • The thyroid gland consists of two lobes on the ventral surface of the trachea
    • It produces two iodine-containing hormones: triiodothyronine (T 3 ) and thyroxine (T 4 )
  • 44.  
  • 45.
    • The hypothalamus and anterior pituitary control secretion of thyroid hormones through two negative feedback loops
  • 46. LE 45-9 Hypothalamus TRH Anterior pituitary TSH Thyroid T 3 T 4
  • 47.
    • Thyroid hormones stimulate metabolism and influence development and maturation
    • Hyperthyroidism, excessive secretion of thyroid hormones, can cause Graves’ disease in humans
  • 48.  
  • 49.
    • The thyroid gland also produces calcitonin, which functions in calcium homeostasis
  • 50. Parathyroid Hormone and Calcitonin: Control of Blood Calcium
    • Two antagonistic hormones, parathyroid hormone (PTH) and calcitonin, play the major role in calcium (Ca 2+ ) homeostasis in mammals
  • 51.  
  • 52. LE 45-11 STIMULUS: Rising blood Ca 2+ level Thyroid gland releases calcitonin. Calcitonin Stimulates Ca 2+ deposition in bones Reduces Ca 2+ uptake in kidneys Blood Ca 2+ level declines to set point Homoeostasis: Blood Ca 2+ level (about 10 mg/100 mL) STIMULUS: Falling blood Ca 2+ level Blood Ca 2+ level rises to set point Stimulates Ca 2+ release from bones PTH Parathyroid gland Stimulates Ca 2+ uptake in kidneys Active vitamin D Increases Ca 2+ uptake in intestines
  • 53.
    • Calcitonin stimulates Ca 2+ deposition in bones and secretion by kidneys, lowering blood Ca 2+ levels
    • PTH, secreted by the parathyroid glands, has the opposite effects on the bones and kidneys, and therefore raises Ca 2+ levels
    • PTH also has an indirect effect, stimulating the kidneys to activate vitamin D, which promotes intestinal uptake of Ca 2+ from food
  • 54. Insulin and Glucagon: Control of Blood Glucose
    • The pancreas secretes insulin and glucagon, antagonistic hormones that help maintain glucose homeostasis
    • Glucagon is produced by alpha cells
    • Insulin is produced by beta cells
  • 55.  
  • 56. LE 45-12 Beta cells of pancreas release insulin into the blood. Insulin Liver takes up glucose and stores it as glycogen. STIMULUS: Rising blood glucose level (for instance, after eating a carbohydrate- rich meal) Blood glucose level declines to set point; stimulus for insulin release diminishes. Homeostasis: Blood glucose level (about 90 mg/100 mL) STIMULUS: Dropping blood glucose level (for instance, after skipping a meal) Blood glucose level rises to set point; stimulus for glucagon release diminishes. Liver breaks down glycogen and releases glucose into the blood. Body cells take up more glucose. Alpha cells of pancreas release glucagon into the blood. Glucagon
  • 57. Target Tissues for Insulin and Glucagon
    • Insulin reduces blood glucose levels by
      • Promoting the cellular uptake of glucose
      • Slowing glycogen breakdown in the liver
      • Promoting fat storage
  • 58.
    • Glucagon increases blood glucose levels by
      • Stimulating conversion of glycogen to glucose in the liver
      • Stimulating breakdown of fat and protein into glucose
  • 59. Diabetes Mellitus
    • Diabetes mellitus is perhaps the best-known endocrine disorder
    • It is caused by a deficiency of insulin or a decreased response to insulin in target tissues
    • It is marked by elevated blood glucose levels
  • 60.
    • Type I diabetes mellitus (insulin-dependent) is an autoimmune disorder in which the immune system destroys pancreatic beta cells
    • Type II diabetes mellitus (non-insulin-dependent) involves insulin deficiency or reduced response of target cells due to change in insulin receptors
  • 61. Adrenal Hormones: Response to Stress
    • The adrenal glands are adjacent to the kidneys
    • Each adrenal gland actually consists of two glands: the adrenal medulla and adrenal cortex
  • 62.  
  • 63. Catecholamines from the Adrenal Medulla
    • The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline)
    • These hormones are members of a class of compounds called catecholamines
    • They are secreted in response to stress-activated impulses from the nervous system
    • They mediate various fight-or-flight responses
  • 64. Stress Hormones from the Adrenal Cortex
    • Hormones from the adrenal cortex also function in response to stress
    • They fall into three classes of steroid hormones:
      • Glucocorticoids, such as cortisol , i nfluence glucose metabolism and the immune system
      • Mineralocorticoids, such as aldosterone , a ffect salt and water balance
      • Sex hormones a re produced in small amounts
  • 65. LE 45-13 Stress Hypothalamus Anterior pituitary Blood vessel ACTH ACTH Releasing hormone Nerve cell Nerve cell Long-term stress response Effects of mineralocorticoids: 1. Retention of sodium ions and water by kidneys 2. Increased blood volume and blood pressure Effects of glucocorticoids: 1. Proteins and fats broken down and converted to glucose, leading to increased blood glucose 2. Immune system may be suppressed Short-term stress response Effects of epinephrine and norepinephrine: 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 Nerve signals Spinal cord (cross section) Adrenal gland Kidney
  • 66. Gonadal Sex Hormones
    • The gonads, testes and ovaries, produce most of the sex hormones: androgens, estrogens, and progestins
  • 67.  
  • 68.
    • The testes primarily synthesize androgens, mainly testosterone, which stimulate development and maintenance of the male reproductive system
    • Testosterone causes increase in muscle and bone mass and is often taken as a supplement to cause muscle growth, which carries health risks
  • 69.  
  • 70.
    • Estrogens, most importantly estradiol, are responsible for 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
  • 71. Melatonin and Biorhythms
    • The pineal gland, located in the brain, secretes melatonin
  • 72.  
  • 73.
    • Light/dark cycles control release of melatonin
    • Primary functions of melatonin appear to relate to biological rhythms associated with reproduction
  • 74. Concept 45.5: Invertebrate regulatory systems also involve endocrine and nervous system interactions
    • Diverse hormones regulate homeostasis in invertebrates
    • In insects, molting and development are controlled by three main hormones:
      • Brain hormone stimulates release of ecdysone from the prothoracic glands
      • Ecdysone promotes molting and development of adult characteristics
      • Juvenile hormone promotes retention of larval characteristics
  • 75. LE 45-15_3 Brain hormone (BH) Brain Neurosecretory cells Corpus cardiacum Corpus allatum Prothoracic gland Ecdysone EARLY LARVA LATER LARVA PUPA ADULT Juvenile hormone (JH) Low JH