45 lectures ppt
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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
PowerPoint Lectures for Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
Chapter 45Chapter 45
Hormones and theEndocrine System
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Overview: The Body’s Long-Distance Regulators
• Las hormonas animales son señales 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 células blanco
– Tienen receptores específicos
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• La metamorfosis de los insectos está regulada por hormonas
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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
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 comunicación y regulación interna: el sistema nervioso y el sistema endocrino
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• El sistema nervioso lleva señales eléctricas de alta velocidad a través de células especializadas llamadas neuronas
• El sistema endocrino secreta hormonas que coordinan respuestas más lentas pero más duraderas
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Overlap Between Endocrine and Nervous Regulation
• Ambos sistemas trabajan juntos para mantener la homeostasis, el desarrollo, y la reproducción
• Células nerviosas especializadas llamadas células neurosecretoras liberan neurohormonas a la sangre
• Tanto las hormonas endocrinas como las neurohormonas trabajan como reguladores de larga distancia de muchos procesos fisiológicos
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Control Pathways and Feedback Loops
• Hay tres tipos de trayectos de control hormonal: endocrino, neurohormonal, y neuroendocrino
• Una característica común es un “feedback loop” que conecta la respuesta al estímulo inicial
• La retroalimentación negativa regula muchos de los trayectos hormonales importantes en la homeostasis
LE 45-2aLE 45-2a
Targeteffectors
Response
Simple endocrine pathway
Glycogenbreakdown,glucose releaseinto blood
Liver
Bloodvessel
Pancreassecretesglucagon ( )
Endocrinecell
Low bloodglucose
Receptorprotein
Stimulus
Pathway Example
LE 45-2bLE 45-2b
Targeteffectors
Response
Simple neurohormone pathway
Stimulus
Pathway Example
Suckling
Milk release
Smooth musclein breast
Neurosecretorycell
Bloodvessel
Posterior pituitarysecretes oxytocin( )
Hypothalamus/posterior pituitary
Sensoryneuron
LE 45-2cLE 45-2c
Targeteffectors
Response
Simple neuroendocrine pathway
Stimulus
Pathway Example
Milk production
Bloodvessel
Hypothalamus
Sensoryneuron
Mammary glands
Endocrinecell
Bloodvessel
Anteriorpituitarysecretesprolactin ( )
Hypothalamussecretes prolactin-releasinghormone ( )
Neurosecretorycell
Hypothalamicneurohormonereleased inresponse to neural andhormonalsignals
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Concept 45.2: Hormones and other chemical signals bind to target cell receptors, initiating pathways that culminate in specific cell responses
• Hormonas llevan la información via la sangre hacia las células blanco a través del cuerpo
• Tres clases de moléculas trabajan como hormonas en los vertebrados:
– Proteínas y péptidos
– Aminas derivadas de aminoácidos
– Esteroides
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• Signaling by any of these hormones involves three key events:
– Reception
– Signal transduction
– Response
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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
LE 45-3LE 45-3
SECRETORYCELL
Hormonemolecule
Signal receptor
VIABLOOD
VIABLOOD
TARGETCELL TARGET
CELLSignaltransductionpathway
OR
Cytoplasmicresponse
DNA
NUCLEUS
Nuclearresponse
Receptor in plasma membrane Receptor in cell nucleus
DNA
NUCLEUS
mRNA
Synthesis ofspecific proteins
Signaltransductionand response
Signalreceptor
Hormonemolecule
SECRETORYCELL
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• 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
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• The hormone epinephrine has multiple effects in mediating the body’s response to short-term stress
LE 45-4LE 45-4
Different receptors different cell responses
Epinephrine
receptor
Epinephrine
receptor
Epinephrine
receptor
Vesselconstricts
Vesseldilates
Intestinal bloodvessel
Skeletal muscleblood vessel
Liver cell
Different intracellular proteins different cell responses
Glycogendeposits
Glycogenbreaks downand glucoseis releasedfrom cell
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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
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Paracrine Signaling by Local Regulators
• In paracrine signaling, nonhormonal chemical signals called local regulators elicit responses in nearby target cells (la respuesta es más rápida)
• Types of local regulators:
– Neurotransmitters (derivados de aa)
– Cytokines (respuesta inmunológica) and growth factors (estimulan proliferación celular y diferenciación)
– Nitric oxide (si O2 baja,
– Prostaglandins
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• Prostaglandins help regulate aggregation of platelets, an early step in formation of blood clots
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• 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.
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• 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.
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• 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.
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• 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.
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• 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
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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 45-6LE 45-6
Testis(male)
Ovary(female)
Adrenal glands
Pancreas
Parathyroid glands
Thyroid gland
Pituitary gland
Pineal gland
Hypothalamus
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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
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LE 45-7LE 45-7
Mammary glands,uterine muscles
Hypothalamus
Kidney tubules
OxytocinHORMONE
TARGET
ADH
Posteriorpituitary
Neurosecretorycells of thehypothalamus
Axon
Anteriorpituitary
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• 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
LE 45-8LE 45-8
Neurosecretory cells of the hypothalamus
Endocrine cells of theanterior pituitary
Portal vessels
Pituitary hormones(blue dots)
Pain receptorsin the brain
Endorphin Growth hormone
BonesLiver
MSH
Melanocytes
Prolactin
Mammaryglands
ACTH
Adrenalcortex
TSH
ThyroidTestes orovaries
FSH and LH
TARGET
HORMONE
Hypothalamicreleasinghormones(red dots)
Tropic Effects OnlyFSH, follicle-stimulating hormoneLH, luteinizing hormoneTSH, thyroid-stimulating hormoneACTH, adrenocorticotropic hormone
Nontropic Effects OnlyProlactinMSH, melanocyte-stimulating hormoneEndorphin
Nontropic and Tropic EffectsGrowth hormone
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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
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Anterior Pituitary Hormones
• The anterior pituitary produces both tropic and nontropic hormones
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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
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Nontropic Hormones
• Nontropic hormones produced by the anterior pituitary:
– Prolactin
– Melanocyte-stimulating hormone (MSH)
– -endorphin
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• 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
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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
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Concept 45.4: Nonpituitary hormones help regulate metabolism, homeostasis, development, and behavior
• Many nonpituitary hormones regulate various functions in the body
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Thyroid Hormones
• The thyroid gland consists of two lobes on the ventral surface of the trachea
• It produces two iodine-containing hormones: triiodothyronine (T3) and thyroxine (T4)
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• The hypothalamus and anterior pituitary control secretion of thyroid hormones through two negative feedback loops
LE 45-9LE 45-9
Hypothalamus
TRH
Anteriorpituitary
TSH
Thyroid
T3 T4
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• Thyroid hormones stimulate metabolism and influence development and maturation
• Hyperthyroidism, excessive secretion of thyroid hormones, can cause Graves’ disease in humans
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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• The thyroid gland also produces calcitonin, which functions in calcium homeostasis
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Parathyroid Hormone and Calcitonin: Control of Blood Calcium
• Two antagonistic hormones, parathyroid hormone (PTH) and calcitonin, play the major role in calcium (Ca2+) homeostasis in mammals
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LE 45-11LE 45-11
STIMULUS:Rising blood
Ca2+ level
Thyroid glandreleasescalcitonin.
Calcitonin
StimulatesCa2+ depositionin bones
ReducesCa2+ uptakein kidneys
Blood Ca2+
level declinesto set point
Homoeostasis:Blood Ca2+ level
(about 10 mg/100 mL)
STIMULUS:Falling blood
Ca2+ level
Blood Ca2+
level risesto set point
StimulatesCa2+ releasefrom bones
PTH
Parathyroidgland
Stimulates Ca2+ uptake in kidneys
Activevitamin D
IncreasesCa2+ uptakein intestines
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• Calcitonin stimulates Ca2+ deposition in bones and secretion by kidneys, lowering blood Ca2+ levels
• PTH, secreted by the parathyroid glands, has the opposite effects on the bones and kidneys, and therefore raises Ca2+ levels
• PTH also has an indirect effect, stimulating the kidneys to activate vitamin D, which promotes intestinal uptake of Ca2+ from food
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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
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LE 45-12LE 45-12
Beta cells ofpancreasrelease insulininto the blood.
Insulin
Liver takesup glucoseand stores itas glycogen.
STIMULUS:Rising blood glucose
level (for instance, aftereating a carbohydrate-
rich meal)
Blood glucose leveldeclines to set point;stimulus for insulinrelease diminishes.
Homeostasis:Blood glucose level
(about 90 mg/100 mL)
STIMULUS:Dropping blood glucoselevel (for instance, after
skipping a meal)
Blood glucose levelrises to set point;
stimulus for glucagonrelease diminishes.
Liver breaksdown glycogenand releasesglucose into theblood.
Body cellstake up moreglucose.
Alpha cells of pancreasrelease glucagon into the blood.
Glucagon
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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
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• Glucagon increases blood glucose levels by
– Stimulating conversion of glycogen to glucose in the liver
– Stimulating breakdown of fat and protein into glucose
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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
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• 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
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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
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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
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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, influence glucose metabolism and the immune system
– Mineralocorticoids, such as aldosterone, affect salt and water balance
– Sex hormones are produced in small amounts
LE 45-13LE 45-13
Stress
Hypothalamus
Anterior pituitary
Blood vessel
ACTH
ACTH
Releasinghormone
Nervecell
Nerve cell
Long-term stress response
Effects ofmineralocorticoids:
1. Retention of sodium ions and water by kidneys
2. Increased blood volume and blood pressure
Effects ofglucocorticoids:
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 rate4. Increased metabolic rate
5. Change in blood flow patterns, leading to increased alertness and decreased digestive and kidney activity
NervesignalsSpinal cord
(cross section)
Adrenalgland
Kidney
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Gonadal Sex Hormones
• The gonads, testes and ovaries, produce most of the sex hormones: androgens, estrogens, and progestins
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• 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
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• 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
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Melatonin and Biorhythms
• The pineal gland, located in the brain, secretes melatonin
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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Light/dark cycles control release of melatonin
• Primary functions of melatonin appear to relate to biological rhythms associated with reproduction
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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
LE 45-15_3LE 45-15_3
Brainhormone (BH)
Brain
Neurosecretorycells
Corpuscardiacum
Corpusallatum
Prothoracicgland
Ecdysone
EARLYLARVA
LATERLARVA PUPA ADULT
Juvenilehormone(JH)
LowJH