Y khoa, dược - The endocrine system

30The Endocrine System30-2Learning Outcomes30.1 Define the term endocrine glands.30.2 Describe the general functions of the endocrine system.30.3 Define the term hormone.30.4 Explain the difference in hormone control by positive and negative feedback loops.30-3Learning Outcomes (cont.)30.5 Describe the locations of the hypothalamus, pituitary gland, pineal body, thyroid gland, parathyroid glands, adrenal glands, pancreas, thymus, and gonads.30.6 List the hormones released by the pituitary gland and give the functions of each.30.7 List the hormones released by the thyroid gland and parathyroid glands and give the functions of each.30-4Learning Outcomes (cont.)30.8 List the hormones released by the adrenal glands and give the functions of each.30.9 List the names of the endocrine cells of the pancreas, the hormones released by them, and the function of each hormone.30.10 List the hormones released by the pineal body, thymus, and gonads, and give the functions of each. 30-5Learning Outcomes (cont.)30.11 Name the hormones produced by the kidneys and heart, listing which organ produces the hormone, and the hormone’s function.30.12 Describe stressors and their effect on the body.30.13 Describe the causes, signs and symptoms, and treatment of various endocrine disorders.30-6target tissuesIntroductionThe endocrine system includes the organs of the body that secrete hormones directly into body fluids such as bloodRegulates chemical reaction in cells and therefore control functions of the organs, tissues, and other cellsGlandssecretehormonesintobloodstreamto30-7Hormones Endocrine glands DuctlessRelease hormones Directly into target tissuesInto bloodstream to be carried to target tissuesHormones – chemicals secreted by a cell that affect the functions of other cells30-8Hormones (cont.)Many are derived from steroids that easily cross the cell membrane Examples of steroidal hormonesEstrogenProgesteroneTestosteroneCortisolHormones30-9Hormones (cont.)Nonsteroidal hormonesMade of amino acids or proteins and cannot cross the cell membrane easilyBind to receptors on the surface of the cellsG-protein – activated by the hormone-receptor complexActivates enzymes inside cellProstaglandinsLocal, or tissue, hormonesDerived from lipid moleculesDo not travel in the bloodstreamTarget tissues are located close byProduced by organs such asKidneysHeartStomach UterusBrain 30-10Feedback LoopsControl hormone levelsNegative feedback loopHormone release stops in response to decrease in stimulusStimulus (eating) raises blood glucose levelsPancreas releases insulin in response to elevated blood glucoseBlood glucose decreases as it is used by the body or stored in the liverInsulin release stops as blood glucose levels normalize30-11Feedback Loops (cont.)Positive feedback loopAs long as stimulus is present, action of hormone continuesInfant nursing at mother’s breast  stimulates hypothalamus  stimulates posterior pituitaryOxytocin released  stimulates milk production and ejection from mammary glandsMilk release continues as long as infant continues to nurse30-12Apply Your KnowledgeMatch the following:___ Chemicals that effect cell function A. Nonsteroidal hormone___ Easily cross cell membranes B. Steroidal hormone___ Made of amino acids C. G-protein___ Target nearby cells D. Prostaglandins___ Activated by hormone-receptor E. Hormones complex___ Cannot cross cell membranes easily___ Estrogen and cortisolBADCABEANSWER:VERY GOOD!30-13HypothalamusHormonesOxytocinAntidiuretic hormone (ADH)Hormones transported to the posterior pituitary for storage Directs posterior pituitary to release hormones Glands30-14Pituitary GlandControlled by the hypothalamusLocated at the base of the brain Protected by a bony structure called the sella turcica The optic chiasm is located just above the pituitary glandCarries visual information to the brain for interpretationTwo lobesAnterior lobePosterior lobeGlandsPituitary Gland30-15AnteriorLobeGrowth hormoneProlactinAdrenocorticotropic (ACTH)Thyroid-stimulating (TSH)Follicle-stimulatingLuteinizingStimulates milk productionStimulates the adrenal cortex to release its hormonesStimulates the thyroid gland to release its hormonesFemales: stimulates estrogen production and maturation of the ovaMales: stimulates sperm productionFemales: stimulates ovulationand estrogen productionMales: stimulates testosterone production Pituitary Gland (cont.)Stimulates increase in size of muscles and bones30-16PosteriorLobeAntidiuretic hormone (ADH)OxytocinStimulates the kidneys to conserve waterFemales: causes contraction of the uterus and ejection of breast milkMales: stimulates contraction of the prostate and vas deferens during sexual arousalPituitary Gland (cont.)30-17Apply Your KnowledgeMatch the following: ___ Stored in posterior pituitary A. Follicle-stimulating hormone___ Milk production B. Prolactin___ Produced by hypothalamus C. Luteinizing hormone___ Stimulates sperm production D. ADH___ Maturation of ova E. Oxytocin___ Stimulates ovulation ___ Conservation of water___ Production of testosterone___ Contraction of uterusEDBD, ECAACD, EANSWER:Super!30-18CalcitoninThyroid hormonesT3 T4Thyroid Gland Located below the larynx Divided into follicles that store some of the hormonesMajor hormonesStimulate protein synthesis and increase cellular energy productionLowers blood calcium levels by activating osteoblasts that build new bone tissueGlands30-19Parathyroid GlandsFour located on the posterior surface of the thyroid glandSecrete parathyroid hormone (PTH)Agonist to calcitonin by raising blood calcium levels through activation of osteoclasts (dissolve bone)As bone dissolves, calcium levels in blood increaseGlands30-20Apply Your KnowledgeTrue or False: __ Thyroid hormones stimulate protein synthesis.__ The thyroid gland does not store hormones.__ PTH activates osteoblasts.__ Calcitonin increases cellular energy production.__ The four parathyroid glands are located on the thyroid gland.__ Calcitonin lowers blood calcium levels.FFFTTTANSWER:Bravo!PTH activates osteoclasts.Thyroid hormone increases cellular energy production.Thyroid follicles store some hormones.30-21Adrenal GlandsLocated on top of each kidneyDivided into the adrenal medulla and adrenal cortexAdrenal medullaCentral portionHormones Epinephrine NorepinephrineSame effects as sympathetic nervous system Glands30-22Adrenal Glands (cont.)Adrenal cortexOutermost portion Secretes many hormones, but main ones areAldosteroneStimulates body to retain sodium and waterImportant in maintaining BPCortisol Released when stressedDecreases protein synthesis, resulting in slowed tissue repairDecreases inflammation30-23Apply Your KnowledgeMatch the following:____ Adrenal medulla A. Cortisol____ Sodium retention B. Epinephrine____ Decreases inflammation C. Aldosterone____ Sympathetic effects D. Norepinephrine____ Maintains blood pressure____ Released during stress____ Adrenal cortexA, CB, DACACB, DANSWER:Excellent!30-24PancreasLocated behind the stomachBoth exocrine gland and endocrine glandExocrine – secretes digestive enzymes into a duct leading to the small intestineEndocrine – secretes hormones into bloodstreamGlands30-25Pancreas (cont.)Islets of Langerhans secrete hormones into bloodstreamAlpha cells secrete glucagonBeta cells secrete insulin InsulinBlood glucose concentrationsProtein synthesisGlucagonBlood glucose concentrationsProtein synthesis30-26Apply Your KnowledgeWhat are the effects of insulin and glucagon?ANSWER: Insulin decreases blood glucose concentration and increases protein synthesis.Glucagon does just the opposite. It increases blood glucose and decreases protein synthesis.Yippee!30-27Other Hormone-Producing Organs Pineal bodySmall glandLocated between cerebral hemispheresMelatoninRegulates circadian rhythmsMay play a role in onset of pubertyThymus glandLocated between lungsThymosinPromotes production of T lymphocytesGlands30-28Other Hormone-Producing Organs (cont.)The gonadsOvariesEstrogenProgesteroneTestes Testosterone StomachGastrinSmall intestineSecretinCholecystokinin Heart Atrial natriuretic peptide – regulates BPKidneys Erythropoietin – stimulates blood cell productionGlands30-29BackBack30-30Apply Your KnowledgeMatch the following:___ Between lungs A. Pineal body___ Melatonin B. Heart___ Estrogen/testosterone C. Kidneys___ Gastrin D. Thymus gland___ Secretin E. Small intestine___ Erythropoietin F. Stomach ___ Atrial natriuretic peptide G. Gonads___ Thymosin___ CholecystokininCEFGAEDBDANSWER:Good Job!30-31The Stress ResponseStressor Any stimulus that produces stressTypes Physical factors Psychological factorsPositive stimuli30-32The Stress Response (cont.)Physiologic response to stress caused by hormone releaseGeneral stress syndromeIncreased heart rate, respiratory rate, and BPIncrease in glucose and fatty acids in blood, which leads to weight lossIncrease in cortisol if stress prolongedDecreased body repairSusceptibility to illness30-33Apply Your KnowledgeMatch the following:___ Extreme heat A. Physical stress___ Death of friend B. Psychological stress___ Fractured leg C. Positive stimulus___ Wedding___ Exam___ Hearing an explosion nearby___ “A” on an exam___ Flu___ Car stolenBBBAACBCAANSWER: Very Good!30-34Common Diseases and DisordersDisease/DisorderDescriptionAcromegalyToo much growth hormone produced in adults; enlargement of bones and thickened skinAddison’s diseaseAdrenal gland fails to produce enough corticosteroidsCretinismExtreme form of hypothyroidism present prior to or soon after birthCushing’s diseaseHypercortisolism; over-production of cortisolDiabetes insipidusKidneys fail to reabsorb water, resulting in excessive urination; hyposecretion of ADH30-35Common Diseases and Disorders (cont.)Disease/DisorderDescriptionDiabetes mellitusType IType IIGestationalChronic disease characterized by elevated blood glucose levelsInsulin-dependent diabetes mellitus; usually develops in childhoodNoninsulin-dependent diabetes mellitus; primarily in adults but increased incidence in teens Occurs during pregnancy; usually temporaryDwarfismToo little growth hormone (somatotropin) produced during childhood30-36Common Diseases and Disorders (cont.)Disease/DisorderDescriptionGigantismToo much growth hormone produced during childhoodGoiterEnlargement of thyroid gland, causing swelling in neck; deficiency of iodine in dietGraves’ diseaseHyperthyroidism; antibodies attach to thyroid gland, causing it to produce too much thyroid hormoneMyxedemaThyroid gland produces inadequate amounts of thyroid hormone; common in females over 5030-37Apply Your KnowledgeTrue or False:___ Acromegaly develops as a result of too much growth hormone in a  child.___ In diabetes insipidus, the kidneys fail to reabsorb water.___ Too little growth hormone in childhood results in dwarfism.___ Myxedema is the result of hyperthyroidism.___ Addison’s disease is the result of too little corticosteroid.___ Cushing’s disease is the result of too little ACTH.___ Cretinism is an extreme form of hyperthyroidism present at birth.FTTTFFANSWER:Fhypothyroidismtoo much ACTHhypothyroidismin an adultCorrect!30-38In Summary30.1 Endocrine glands are ductless glands, releasing hormones directly into the bloodstream and tissues.30.2 The organs of the endocrine system produce hormones that regulate the chemical reactions within cells, controlling the functions of organs, tissues, and other cells.30.3 Hormones are chemicals released by cells that affect the functioning of other cells.30-39In Summary (cont.)30.4 In a negative feedback loop, a stimulus causes a body reaction, which is detected by another area of the body, which stops the reaction. The rise in blood sugar causing the pancreas to release insulin to lower blood sugar is an example. In a positive feedback loop, a stimulus begins a process which will continue as long as the stimulus continues; as happens with a nursing infant, where the suckling releases milk from the mother’s breast until the suckling stops.30-40In Summary (cont.)30.5 The hypothalamus, pituitary, and pineal glands are located within the brain. The thyroid and parathyroid glands are located in the neck. The thymus is found in the mediastinum. The adrenal glands are located above each kidney, and the pancreas is located behind the stomach. In females, the gonads (ovaries) are in the abdominal cavity and in males, the gonads (testes) are found within the scrotal sac.30-41In Summary (cont.)30.6 The pituitary gland releases the following hormones: GH, MSH, ACTH, TSH, FSH, LH, PRL, ADH and OT. Each hormone’s specific function may be found in Table 30-1.30.7 The thyroid gland releases calcitonin, T3, and T4 which are important in growth and protein synthesis. The parathyroid releases PTH which balances the action of calcitonin. 30-42In Summary (cont.)30.8 The adrenal medulla secretes epinephrine and norepinephrine, which work with the sympathetic nervous system. The adrenal cortex produces many hormones, but the two major ones are aldosterone for BP maintenance and cortisol, which decreases inflammation.30.9 The endocrine cells of the pancreas are known as the Islets of Langerhans. The two types of cells are Alpha cells, which release glucagon, and Beta cells, which release insulin.30-43In Summary (cont.)30.10 The pineal body releases melatonin to regulate circadian rhythms, the thymus releases thymosin and thymopoietin to promote T cell production, ovaries release estrogen and progesterone (females), and the testes (males) release testosterone.30.11 The kidneys produce erythropoietin, affecting the bone marrow, and the heart produces atrial natriuretic peptide, affecting BP.30-44In Summary (cont.)30.12 Stressors are defined as stimuli that produce a stress response, a physiologic response to the stimulus that changes the body’s functioning in some way.30.13 The diseases and disorders of the endocrine system are as varied as the organs and hormone dysfunctions that cause them. An overview of these conditions is in Table 30-2, and more detail on the most common of these conditions is found in the Pathophysiology section at the end of this chapter.30-45End of Chapter 30Its not stress that kills us, it is our reaction to it. ~ Hans Selye