第12章--内分泌系统.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Endocrine system:,The endocrine system consists of a number of glands located throughout the body that produce and secrete substances called hormones into the blood.,A hormone is a chemical that influences or controls the activity of a specific tissue or organ.,Like the nervous system,the endocrine system coordinates the functioning of body parts.The nervous system is fast acting and utilizes nerve impulses that travel rapidly along nerve fibers.The endocrine system is slower acting because it takes time to deliver hormones to target organs,but the action of hormones is longer lasting.,Endocrine Glands:Because endocrine glands eventually lose their ducts,they are often called ductless glands.They produce hormones,regulatory chemicals that they secrete directly into the extracellular space.The hormones enter the blood or lymphatic fluid.,Exocrine Glands:are far more numerous than endocrine glands,and many of their products are familiar.The multicellular glands secrete their products through a duct onto body surfaces or into body cavities.Exocrine glands are a diverse lot.They include mucous,sweat,oil,and salivary glands,the liver,the pancreas,and many others.,本章主要内容,一、化学调节的性质,二、脊椎动物的化学调节,三、激素与稳态,重点,:,激素的作用特点,两类激素的作用机制，腺垂体、,甲状腺、,胰岛素、,糖皮质激素、肾上腺髓质激素的作用。,激素调节的一般特征,：,（1）信使作用;,（2）相对特异性;（3）高效性;,（4）激素间的相互作用；（5）激素调节比神经调节慢，但作用持久。,(6)激素的分泌有节律性。,激素的作用,：,（,1）维持稳态。,（2）促进生长发育。,（3）促进生殖活动。,（4）调节能量转换。,（5）调节行为,。,生长激素促甲状腺激素促肾上腺皮质激素,促性激素,胰高压糖素胰岛素,甲状腺激素,睾丸酮、雌激素、孕激素,肾上腺皮质激素、,糖皮质激素,根据激素的化学成分分类：,含碘的氨基酸,肽和蛋白质,类固醇激素,作用时间长,含氮激素,作用迅速,2.激素的作用机制,The chemistry of hormones:,Hormones may be defined as chemical substances,secreted by cells into the extracellular fluids,that regulate the metabolic function of other cells in the body.Although a large variety of hormones are produced,nearby all of them can be classified chemically as either,amino,acid-based hormones or steroids,.,Most hormones belong to the first group.Molecular size varies widely in this groupfrom the simple amino acid derivatives,which include the amines and thyroxine to peptides(short chains of amino acids),to proteins(long polymers of amino acids).Hormones of the second group,the steroids,are synthesized from cholesterol.Of the hormones produced by the major endocrine organs,only the gonadal hormones and adrenocortical hormones are steroids,激素受体,：指靶细胞上能识别并专一性结合某种激素，继而引,起各种生物效应的功能蛋白质。,激素受体的分类：,细胞膜受体,：G蛋白耦联受体和酪氨酸蛋白激酶受体,结构分为膜外区段、质膜部分和膜内区段,细胞内受体,：分为胞浆受体和核受体,核受体的结构分为激素结合结构域、DNA结合 结构域和转录,激活结构域,2.1含氮激素的作用机制,第二信使学说,激素(第一信使)与靶细胞上的受,激活 催化,体结合 腺苷环化酶,ATP （胞内）,cAMP 酶反应 生理活动,(第二信使）,2.1含氮激素的作用机制,第二信使学说（肾上腺素的作用）,作为第一信使的激素在血液中的含量虽然极低，但通过细胞的信号传导途径，微弱的化学信号可以被逐级放大。,Amino acid-based hormones and second-messenger systems:,Because proteins and peptides cannot penetrate the plasma membranes of tissue cells,virtually all of the amino acid-based exert their signaling effects through intracellular second messengers generated by hormone binding to plasma membrane receptors.Of the second messengers,cyclic AMP,which also mediates the effects of certain neurotransmitters,is by far the best understood,so it will receive most of our attention.,Amino acid-based hormones or peptide hormones act as messengers that stimulate cells by binding to specific receptors in the plasma membrane.The hormone receptor complex activates an enzyme that produces cyclic AMP(cAMP),a compound derived from ATP.cAMP,serving as a so-called second messenger,then activates other enzymes that carry out various cellular activities.Other peptide hormones utilize calcium(Ca,2+,)as a second messenger.,2.2类固醇激素作用机制基因表达学说,类固醇激素进入细胞内，与胞浆靶受体分子结合后，启动了细胞核内相关基因表达。,Steroid hormones and direct gene activation:,Being lipid soluble,steroid hormone(and,strangely,thyroid hormone,a small iodinated amine)can diffuse easily into their target cells.Once inside,they bind to an intracellular receptor that is activated by the coupling.The activated hormone-receptor complex then makes its way to the nuclear chromatin,where the hormone binds to a DNA-associated receptor protein specific for it.This interaction“turns on”a gene,that is,it prompts transcription of DNA to produce a messenger RNA(mRNA).The mRNA is then translated on the cytoplasmic ribosomes,producing specific protein molecules.These proteins include enzymes that promote the metabolic activities induced by that particular hormone and,in some cases,synthesis of structural proteins that are exported by the target cell.,Cellular activity of hormones:,Peptide hormones combine with receptors located on the plasma membrane.This promotes the production of cyclic AMP which,in turn,leads to activation of particular enzymes.,Steroid hormones pass through the plasma membrane to bind with receptors;the hormone receptor complex moves into the nucleus and activates certain genes,leading to protein synthesis.,二、脊椎动物的化学调节,1.脊椎动物的内分泌系统,2.内分泌系统与神经系统的联系,3.垂体的内分泌功能,1.脊椎动物的内分泌系统,内分泌系统,：是由内分泌腺和分散存在于某些组,织器官中的内分泌细胞组成的一个信息传递系统。,内分泌腺,:垂体、甲状腺、甲状旁腺、肾上腺、胰岛、性腺、松果体、胸腺,内分泌细胞,：消化道粘膜、心、肾、肺、皮肤、胎盘等部位存在各种内分泌细胞,兼有内分泌功能的细胞,：神经内分泌细胞,Compared to other organs of the body,the organs of the endocrine system are small and unimpressive.Indeed,to collect 1 kg of hormone-producing tissue,you would need to collect all of the endocrine tissue from eight or nine adults!In addition,the anatomical continuity typical of most organ systems does not exist between the endocrine organs.Instead,endocrine organs are widely scattered about the body.,The endocrine glands of the body include the pituitary,thyroid,parathyroid,adrenal,pineal,and thymus glands.In addition,several organs of the body contain discrete areas of endocrine tissue and produce hormones as well as exocrine products.Such organs,which include the pancreas and gonads,are also major endocrine glands.The hypothalamus also falls into this latter category.Along with its neural functions,it produces and releases hormones,so we can consider the hypothalamus a neuroendocrine organ.,Besides the major endocrine organs,various other tissues and organs produce hormones.For example,pockets of hormone-producing cells are found in the walls of the small intestine,stomach,kidneys,and heartorgans whose chief functions have little to do with hormone production.These.,人体主要内分泌腺,2.内分泌系统与神经系统的联系,哈里斯的下丘脑调节腺垂体的神经-体液学说:,下丘脑 腺垂体 靶腺体,下丘脑是身体,内分泌系统的总,枢纽，它通过垂体,将神经系统与,内分泌系统,有机地联系起来。,3.垂体的内分泌功能,Hypothalamus and the pituitary.The hypothalamus produces two hormones,ADH and oxytocin,which are stored and secreted by the posterior pituitary.The hypothalamus controls the secretions of the anterior pituitary,and the anterior pituitary controls the secretions of the thyroid,adrenal cortex,and gonads,which are also endocrine glands.,促激素:,促肾上腺皮质激素、促甲,状腺激素、促卵泡激素、促黄体,素、促黑色细胞刺激素,腺 垂 体 生长激素(growth hormone,GH),催乳素,垂体 抗利尿激素（ADH),神经垂体,催产素,垂体位于脑下部的垂体窝内，借漏斗连于下丘脑。,Posterior pituitary:,The posterior pituitary is connected to the hypothalamus by means of a stalklike structure.The hormones released by the posterior pituitary are made by neurosecretory cells in the hypothalamus.The hormones then migrate through axons that terminate in the posterior pituitary.,Antidiuretic hormone,(ADH),also called vasopressin,promotes the reabsorption of water from the kidneys,thereby preventing dehydration.The hypothalamus is believed to contain cells that are sensitive to blood solute concentrations.When these cells detect that the blood lacks sufficient water,ADH is produced by special neurosecretory cells and is transported by their fibers to the posterior pituitary,where it is released.As the blood becomes more dilute,the hormone ceases to be produced and released.Inability to produce ADH causes diabetes insipidus,in which a person produces copious amounts of urine with a resultant loss of electrolytes from the blood.The condition can be corrected by the administration of ADH.,Oxytocin,is another hormone made in the hypothalamus and released by the posterior pituitary.Oxytocin causes the uterus to contract and can be used to artificially induce labor.It also stimulates the release of milk from the breast when a baby is nursing.,下丘脑通过分泌释放激素或释放抑制激素来控制脑垂体前叶（腺垂体）的活动。,促甲状腺素释放激素（TRH）：为3肽，促进TSH和PRL分泌。,促肾上腺皮质激素释放激素（CRH）：多肽，促进ACTH分泌,卵泡刺激素释放激素（FRH):10肽，促进FSH分泌,黄体生成素释放激素（LRH）：10肽，促进LH分泌,生长素释放激素（GRH）：10肽，促进GH分泌,生长素释放抑制激素（GRIH)：14肽，抑制GH及TSH的分泌,催乳素释放激素（PRH）：促进催乳素分泌,催乳素释放抑制激素（PRIH）：抑制催乳素分泌,促黑激素释放激素（MRH）：5肽，促进MSH分泌,促黑激素释放抑制因子（MRIH）：3肽，抑制MSH分泌,生长激素,蛋白质合成,骨的生长,生长发育,促进代谢,甲状腺激素,性激素,雌激素雄激素孕激素,促甲状腺激素释放激素,甲状腺,生长激素释放因子,下丘脑,(内分泌活动的调节中枢),促甲状腺激素,垂体,促性腺激素释放激素,促性腺激素,睾丸或卵巢,生殖器官第二性征,子宫内膜和乳腺,Anterior pituitary:,The hypothalamus controls the anterior pituitary by producing hypothalamic-releasing and release-inhibiting hormones,which are transported to the anterior pituitary by the blood within a portal system.Each of these hypothalamic hormones causes the anterior pituitary either to secrete or to stop secreting a specific hormone.The anterior pituitary produces several different hormones as followed figure.,Negative feedback in the regulation of the hypothalamus,anterior pituitary,and thyroid.,a.the level of thyroid-stimulating hormones(TSH)exerts feedback control over the hypothalamus.,b.the level of thyroxine exerts feedback control over the anterior pituitary.,c.the level of thyroxine exerts feedback control over the hypothalamus.In this way,thyroxine controls its own secretion.Cortisol and sex hormone levels are controlled in similar ways.,促激素的功能：,维持相关腺体的正常发育,促进相关腺体内激素合成和分泌,生长激素的功能：,蛋白质合成和骨的生长。,催乳素：,促进乳汁的合成分泌。,生长激素分泌异常,侏儒症,巨人症,16岁的姚德芬身高2.36米，体重180公斤，,她的身高是长年罹患垂体瘤导致“巨人症”的结果。,Growth hormone(GH):,Growth hormone,or somatotropin,produced by the anterior pituitary,affects the physical appearance dramatically since it determines an individuals size and height.If little or no GH is secreted by the anterior pituitary during childhood,a person can become a pituitary dwarf,characterized by perfect proportions but small stature.If too much GH is secreted,a person can become a giant.Giants usually have poor health,primarily because GH has a secondary effect on the blood sugar level,promoting an illness called diabetes mellitus.,GH is produced in greatest quantities during childhood and adolescence,when most body growth is occurring,but is still produced(though in lower quantities)in adults to aid in continued protein synthesis and normal cell division and replacement.If GH production increases in an adult after full height has been obtained,only the bones of the jaw,eyebrow ridges,nose,fingers,and toes respond.When these bones begin to grow,the person acquires a slightly grotesque look,with huge fingers and toes.This condition is called acromegaly.,Prolactin(PRL):,PRL is produced by the anterior pituitary only after childbirth.It causes the mammary glands in the breast to develop and produce milk.,The anterior pituitary also secretes the hormones that follow.Since these hormones have effect on other endocrine glands,the anterior pituitary is sometimes called the master gland.,三、激素与稳态,1.甲状腺调节发育与代谢,2.甲状旁腺维持钙稳定,3.胰腺调节血糖水平,4.肾上腺髓质动员应急反应,5.肾上腺皮质的内分泌是维持生命所必需的,6.性腺分泌性激素,1.甲状腺调节发育与代谢:,位于颈前部,喉下部、气管上部的两侧和前面。呈H形，是人体内最大的内分泌腺。,甲状腺分泌,甲状腺激素。,The thyroid gland:,The butterfly-shaped thyroid gland is located in the anterior neck,on the trachea just inferior to the larynx.Its two lateral lobes are connected by a median tissue mass called the isthmus.The thyroid gland is the largest pure endocrine gland in the body.Its prodigious blood supply,makes thyroid surgery a painstaking(and bloody)endeavor.,Internally,the thyroid gland is composed of hollow,spherical follicles.The walls of each follicle are formed largely by cuboidal or squamous epithelial cells called follicle cells,which produce the glycoprotein thyroglobulin.The central cavity,or lumen,of the follicle stores colloid,an amber-colored,sticky material consisting of thyroglobulin molecules with attached iodine atoms.Thyroid hormone is derived from this iodinated thyroglobulin.The parafollicular cells,another population of endocrine cells found in the thyroid gland,produce calcitonin,an entirely different hormone.The parafollicular cells lie within the follicular epithelium but protrude into the soft connective tissue that separates and surrounds the thyroid follicles.,甲状腺激素的合成与代谢,有两种：T3和T4,合成的原料：碘和酪氨酸,合成过程分为三步：,（一）甲状腺腺泡聚碘,聚碘,是逆电化学剃度的继发性主动转运,（二）,I,-,的活化,I,-,在过氧化酶的作用下,变成,I,2,或,I,0,（三）酪氨酸碘化与甲状腺激素的合成,甲状腺球蛋白酪氨酸残基上的氢原子可被碘原子取代或碘化，首先生成一MIT和DIT，然后两DIT耦联T,4,；一个MIT与一个DIT发生耦联，形成T,3,（四）甲状腺激素的贮存、释放、运输与代谢,1贮存：在腺泡腔内以胶质的形式贮存。,2,释放,：,3,运输,：,以两种形式在血液中运输，一种是与血浆蛋白结合，另一种则呈游离状态,。,4,代谢：血浆,T,4,半衰期为,7,天，,T,3,半衰期,1.5,天。,（,二）甲状腺激素的生理作用,主要作用是促进物质与能量代谢，促进生长和发育过程，提高产热量。,1.对代谢的影响,a.产热效应,：提高组织耗氧率，增加产热量，与Na,+,-K,+,-ATP 酶有关。甲亢时，产热量增加，基础代谢率升主患者喜凉怕热，极易出汗；功能低下时，产热量减少，基础代谢率降低，患者喜热恶寒。,对蛋白质、糖 和脂肪代谢的影响,蛋白质：生理剂量促进合成；过多加速分解，,导致消瘦；不足，蛋白质合成减少，,但组织间的粘蛋白增 多，,引起粘液性水肿（myxedema）。,糖：提高血糖,，,促进糖的吸收,；,增强糖原,分解,，抑制糖原合成,；,增强肾上腺素、,胰高血糖素、,皮质醇和 生长素的生糖作用,。,脂肪,：促进脂肪的分解，对胆固醇,以分解为主。,2.,对生长与发育的影响,维持正常生长发育不可缺少的激素，,特别是对,骨和脑的发育尤为重要。,幼年时缺乏患呆小症（cretinism）。,甲状腺机能不足发生在成年则引起粘液性水肿。,3.对神经系统的影响,可提高中枢神经系统的兴奋性。,甲亢时；,注意力不易集中、过敏疑虑多愁善感、喜怒失常、烦躁不安、睡眠不好而且多梦幻，以及肌肉纤颤等,。,功能低下时：中枢神经系统兴奋性降低，出现记 忆力减退，说话和行动迟缓，淡漠无怀与终日 思睡状态。,甲状腺激素对心脏有明显兴奋作用。,Thyroid hormone:,Thyroid hormone,often referred to as the bodys major metabolic hormone,is actually two active iodine-containing hormones,thyroxine,or T,4,and triiodothyronine,or T,3,.thyroxine is the major hormone secreted by the thyroid follicles;most triiodothyronine is formed at the target tissues by conversion of T,4,to T,3,.These two hormones are very much alike.Each is constructed from two thyrosine amino acids linked together,but thyroxine has four bound iodine atoms,whereas triiodothyronine has three.,Except for the adult brain,spleen,testes,uterus,and the thyroid gland itself,thyroid hormone affects virtually every cell in the body.Generally speaking,it stimulates enzymes concerned with glucose oxidation.In this way,it increases basal metabolic rate and body heat production;this is known as the hormones calorigenic effect.Thyroid hormone also provokes an increase in the number of adrenergic receptors in blood vessels,so it plays an important role in maintaining blood pressure.Additionally,it is an important regulator of tissue growth and development;it is specially critical for normal skeletal and nervous system development and maturation and reproductive capabilities.,甲状腺分泌活动的调节,1.,下丘脑,-,腺垂体对甲状腺的调节,2.,甲状腺激素的反馈调节,3.,甲状腺的自身调节,甲状腺本身还具有适应碘的供应变化，调节自身对,碘的摄取以及合成与释放甲状腺激素的能力；,在缺乏,TSH,或,TSH,浓度不变的情况下，这种调节,仍能发生，称为自身调节。,4.,自主神经对甲状腺活动的影响,交感兴奋合成增多，胆碱能神经兴奋,合成减少。,甲状腺机能的异常,1、单纯性甲状腺肿,2、甲状腺机能低下,（1）.呆小症,（2）.黏液性水肿,3、甲亢,Iodine,which is required for thyroxine production,is actively transported into the thyroid gland,where its concentration may be as much as 25 times that found in the blood.If iodine is lacking in the diet,the thyroid gland enlarges,producing a simple goiter.The use of iodized salt helps prevent such a condition.,呆小症（cretinism):,Failure of the thyroid to develop properly results in a condition called cretinism.Cretins are short and stocky,and have had extreme hypothyroidis