3. Hormone Actions at the Target Cell 賀爾蒙在目標細胞的作用. 4. Abnormal Secretion of Hormone 不正常的賀爾蒙分泌

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1 Chapter 6 The Endocrine System: Endocrine Glands and Hormone Actions 1. Primary Endocrine Organs 初級內分泌器官 2. Secondary Endocrine Organs 次級內分泌器官 3. Hormone Actions at the Target Cell 賀爾蒙在目標細胞的作用 4. Abnormal Secretion of Hormone 不正常的賀爾蒙分泌 5. Hormone Interactions 賀爾蒙的交互作用

2 Endocrine glands The organs of the endocrine system 內分泌系統 consist of endocrine glands 內分泌腺, which are derived from epithelial tissue 上皮組織 There are two types of endocrine organs: Primary endocrine organs ( 初級 / 主要內分泌器官 ), whose primary function is the secretion of hormones 主要功能為分泌賀爾蒙 include the hypothalamus 下視丘, pituitary gland 腦下腺, thyroid gland 甲狀腺, adrenal gland 腎上腺, pancreas 胰臟... Secondary endocrine organs ( 次級 / 次要內分泌器官 ), for which the secretion of hormones is secondary to some other function such as heart 心臟, liver 肝臟, stomach 胃, small intestine 小腸, kidney 腎臟, and skin 皮膚 P149

3 Endocrine organs 松果腺下視丘腦下腺 甲狀腺 副甲狀腺胸腺 腎上腺胰臟 卵巢 心臟 胃肝臟腎臟 小腸 睪丸 皮膚 Copyright 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 6.1 Endocrine organs. P150

4 I. Primary endocrine organs 1. Hypothalamus 下視丘 and pituitary gland 腦下腺垂體 2. Pineal gland 松果腺 3. Thyroid gland 甲狀腺 and parathyroid glands 副甲狀腺 4. Thymus 胸腺 5. Adrenal glands 腎上腺 6. Pancreas 胰臟 7. Gonads 性腺

5 Hypothalamus and pituitary gland The hypothalamus is a part of the brain with many functions in addition to its role as an endocrine gland it secretes several hormones, most of which affect the pituitary gland P149 Copyright 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 6.2 Hypothalamus and pituitary gland. (a) Location of the hypothalamus and pituitary gland in the brain. (b) Connection of the hypothalamus and the pituitary gland by the infundibulum 漏斗管. The pituitary gland is divided into an anterior lobe 前葉 and a posterior lobe 後葉. P151

6 Neural connection to posterior pituitary Figure 6.3 Connection between hypothalamus and posterior pituitary gland. Neurons originating in the hypothalamus send projections to the posterior pituitary gland. Neurons originating in the paraventricular nucleus 旁室核 synthesize and secrete ADH 抗利尿激素 (antidiuretic hormone; vasopressin); neurons originating in the supraoptic nucleus 上視核 synthesize and secrete oxytocin 催產素. ADH and oxytocin are secreted from nerve terminals by exocytosis into the bloodstream in the posterior pituitary neurohormones. ADH regulates water balance and osmolarity 調控水的平衡及滲透度 in the kidney & oxytocin stimulates uterine contractions and milk letdown in the breasts 刺激子宮收縮及乳房乳汁分泌 P149 Copyright 2008 Pearson Education, Inc., publishing as Benjamin Cummings. P151

7 Blood connection between hypothalamus and anterior pituitary Figure 6.4 The hypothalamus-pituitary portal system. Neurosecretory cells of the hypothalamus secrete tropic 滋養的 hormones (which are hormones that regulate the secretion of other hormones) into the hypothalamicpituitary portal system 門脈系統. The tropic hormones travel to the anterior pituitary, where they effect release of anterior pituitary 微血管床 hormones into the blood. A portal system is a specialized arrangement of blood vessels 特殊的血管排列 in which two capillary beds are located in series 兩個微血管床連續的串聯在一起, one after the other 靜脈 動脈 P152 門脈靜脈 Copyright 2008 Pearson Education, Inc., publishing as Benjamin Cummings. The portal system enables the hypothalamic tropic hormones to be delivered directly to their target cell in the anterior pituitary, ensuring that these hormones are not diluted and degraded by enzymes in the general circulations 沒有被全身的血液循環稀釋 分解 P149, 151

8 一般血管的排列方式 心臟 大動脈 小動脈 微血管 小靜脈 大靜脈 心臟 門脈系統 (portal system) 1. Hypothalamus-anterior pituitary gland 2. Liver 3. kidney

9 Common tropic hormone pathway Hypothalamus secretes releasing or inhibiting hormone (1) into capillary bed Blood with tropic hormones (1) enters portal vein Hypothalamic tropic hormones (1) access anterior pituitary secretory cells through capillary beds Alter release of anterior pituitary tropic hormones (2) enter bloodstream in same capillary bed Travel to distant endocrine gland to trigger release of hormone (3) 下視丘 Tropic hormone 1 (stimulating or inhibiting) 腦下腺前葉 Tropic hormone 2 (stimulating or inhibiting) 內分泌腺 Hormone 3 P149, 151

10 Tropic hormones of the hypothalamus and anterior pituitary Copyright 2008 Pearson Education, Inc., publishing as Benjamin Cummings. P153 Figure 6.5 Hypothalamic and anterior pituitary tropic hormones. The hypothalamus secretes into the hypothalamic-pituitary portal vein seven tropic hormones that are either releasing hormone [-RH] or inhibiting hormones [-IH]. These tropic hormones act on endocrine cells in the anterior pituitary to stimulate the release of hormones that [except for prolactin] are also tropic hormones. Anterior pituitary tropic hormones act on other endocrine glands to stimulate the release of still other hormones.

11 Tropic Hormones of Hypothalamus and Anterior Pituitary 1. Prolactin releasing hormone (PRH) 泌乳素釋放荷爾蒙 anterior pituitary (AP) prolactin 泌乳素 mammary gland development & milk secretion in females 2. Prolactin inhibiting hormone (PIH) 泌乳素抑制荷爾蒙 or dopamine anterior pituitary (AP) prolactin 3. Thyrotropin releasing hormone (TRH) 甲狀腺釋素 AP thyroid stimulating hormone (TSH) 甲狀腺刺激荷爾蒙 thyroid gland 甲狀腺 thyroid hormone (TH) 甲狀腺荷爾蒙 4. Corticotropin releasing hormone (CRH) 皮釋素 AP adrenocorticotropic hormone (ACTH) 腎上腺皮質刺激素 adrenal cortex 腎上腺皮質 cortisol 5. Growth hormone releasing hormone (GHRH) AP growth hormone (GH) Insulin-like growth factor (IGF) 體介素 & regulates growth and energy metabolism 6. Growth hormone inhibiting hormone (GHIH) or somatostatin 體抑素 AP GH 7. Gonadotropin releasing hormone (GnRH) 性釋素 AP gonadotropin [follicle stimulating hormone (FSH) 濾泡刺激素 ; luteinizing hormone (LH) 黃體刺激素 ] gonads 性腺 sex hormones (estrogens 雌性素 and progesterone 黃體素 in females & androgens 雄性素 in males) P152

12 長的負回饋路徑 短的負回饋路徑 The multistep pathways by which hypothalamic and anterior pituitary tropic hormones are produced are regulated by feedback loops 回饋路徑 P152 Figure 6.6 Negative feedback loops affecting hypothalamic and anterior pituitary hormones. P153

13 Thyroid hormones provide negative feedback 負回饋 only to their own tropic hormones they have no effect, for example, on the cells that secrete GnRH (LH or FSH) P152 Figure 6.7 Regulation of thyroid hormone release. P154

14 Pineal Gland The pineal gland 松果腺, which is located within the brain, is composed of glandular tissue 腺體組織 that secretes the hormone melatonin 退黑激素 The function of melatonin is still a topic of debate 爭論, but most recent studies suggest that it is important in establishing the circadian rhythm 二十四小時節律的建立 It is known, for instance, that melatonin secretion rises at night and falls during the day, and melatonin is a potent sleepinducing 誘導睡眠 agent when administered therapeutically Melatonin also enhances immune function 增強免疫功能 and exerts a suppressive effect on reproductive function 抑制生殖功能 by interfering with the activity of certain hormones Copyright 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 6.2 Hypothalamus and pituitary gland. P153

15 Thyroid gland The thyroid gland 甲狀腺 is a butterfly-shaped 蝴蝶狀 structure located on the ventral surface 前面 of the trachea 氣管 secretes the two thyroid hormones 甲狀腺素, teraiodothyronine (T 4 ) and triiodiothyronine (T 3 ), as well as calcitonin 抑鈣素 thyroid hormones regulate the body s metabolic rate and normal growth 調控身體基礎代謝率及生長 & calcitonin regulate calcium levels in the blood 調節血鈣 Copyright 2008 Pearson Education, Inc., publishing as Benjamin Cummings. 喉嚨 咽 甲狀腺 副甲狀腺 頸動脈 氣管 食道 前面 ( 腹面 ) 後面 ( 背面 ) Figure 6.8 Locations of the thyroid and parathyroid glands. P

16 Parathyroid glands The four parathyroid glands 副甲狀腺 are smaller structures located on the posterior surface 後面 of the thyroid gland secrete parathyroid hormone (PTH) 副甲狀腺素, an important regulator of calcium levels in the blood 重要的血鈣調節者 Copyright 2008 Pearson Education, Inc., publishing as Benjamin Cummings. 喉嚨 咽 甲狀腺 副甲狀腺 頸動脈 氣管 食道 前面 ( 腹面 ) 後面 ( 背面 ) Figure 6.8 Locations of the thyroid and parathyroid glands. P154

17 Thymus The thymus 胸腺 lies close to the heart and secretes the hormone thymosin 胸腺素 regulates T cell function 調節 T 細胞的功能 The thymus is critical for normal immune function because immune cells called T lymphocytes (T cells) T 淋巴細胞, which are essential for effective immune responses against invading microorganisms 有效對抗入侵微生物的免疫反應, mature there 發育成熟的地方 Copyright 2008 Pearson Education, Inc., publishing as Benjamin Cummings. P154

18 Adrenal Glands The adrenal glands 腎上腺 are located above the kidneys 腎臟 suprarenal glands each adrenal gland consists of an outer layer called the cortex 皮質, which accounts for about 80% of the gland s total mass, and an inner core called the medulla 髓質 The adrenal cortex is stratified into three distinct layers these layers possess different complements of the enzymes 擁有不同的酵素 involved in the synthesis of adrenal cortex hormones adrenocorticoids Figure 6.9 Anatomy of the adrenal gland. (a) The adrenal glands 腎上腺, located just above the kidneys 腎臟, are divided into an inner medulla 髓質 and outer cortex 皮質. (b) The adrenal cortex contains three distinct layers, or zonae. 皮質 髓質 絲狀區 束狀區 網狀區 Copyright 2008 Pearson Education, Inc., publishing as Benjamin Cummings. P

19 Adrenal Glands The adrenal cortex secretes a number of hormones collectively called adrenocorticoids include three types of steroid hormones: 1. Mineralocorticoids 礦物皮質酮 (aldosterone 醛固酮 ) secreted from zonae glomerulosa 絲狀層 regulates sodium and potassium levels 調控鈉離子及鉀離子的平衡 2. Glucocorticoids 醣皮質醇 (cortisol 可體松 ) secreted from zonae fasciculata 束狀層 and reticularis 網狀層 regulates body s response to stress; regulates metabolism (protein, carbohydrate, and lipid) & blood glucose levels 調控身體面對壓力 ( 長期 ) 的反應 調控蛋白質 碳水化合物 ( 葡萄糖 ) 及脂質的代謝 3. Sex hormones (androgens 雄性素 ) secreted from zonae fasciculata and reticularis regulate reproductive function (little, but in female, may stimulate the sex drive) 調控生殖功能 ( 較少, 但在女性可能有促進性慾作用 ) The adrenal medula contains chromaffin cells and secretes catecholamines about 80% is epinephrine (adrenaline), about 20% is norepinephrine, and less than 1% is dopamine the secretion is under neural control 其分泌受神經調控 調控身體面對壓力 ( 短期 ) 的反應 P

20 Pancreas Copyright 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 6.9 Anatomy of the pancreas. (a) Located in the abdominal cavity 腹腔 below the stomach. (b) The pancreas consists of acinar cells 腺胞細胞 and duct cells 管細胞 that secrete exocrine 外分泌 products into ducts (GI tracts) and islets of Langerhans 蘭氏小島, which contain cells that secrete endocrine 內分泌 hormones into the interstitial fluid. Four types of endocrine cells are located in the islets; each types secretes a different hormone. Four types of endocrine cells are located in the islets of Langerhans Alpha (a) cells glucagon 升醣素 blood glucose levels 升血糖 Beta (b) cells insulin 胰島素 blood glucose levels 降血糖 Delta (d) cells somatostatin 體抑素 regulate digestion and absorption of nutrients 調節營養物的消化與吸收 F cells pancreatic polypeptide unknown P

21 Gonads The gonads 性腺 (ovaries 卵巢 and testes 睪丸 ) have both endocrine and non-endocrine functions produce the gametes 配子 sperm 精子 in males and oocytes 卵子 in females In males, the predominant sex hormones are the androgens 雄性素, testosterone 睪固酮 and androstenedione In females, the major sex hormones are estradiol 雌二醇 (which belongs to a group of related hormones known as estrogens 雌性素 ) and progesterone 黃體素 The placenta 胎盤 also functions as an endocrine gland in pregnant females 懷孕女性, secreting primarily estrogens and progesterone P155

22 II. Secondary Endocrine Organs In addition to their primary function, many organs of the body also secrete hormones include the heart 心臟, kidneys 腎臟, digestive organs 消化器官, liver 肝臟, and skin 皮膚 Heart atrial natriuretic peptide 心房利鈉胜肽 Kidneys erythropoietin 紅血球生成素, renin 腎素 GI (gastrointestinal) tract 消化道 several Cholecystokinin 膽囊收縮素 Secretin 腸促胰泌素 Gastrin 胃泌素 Liver insulin-like growth factors (somatomedins 體介素 ) Skin & Kidneys calcitriol (vitamin D 3 ) P156

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27 III. Hormone Actions at the Target Cell Factors influencing the magnitude of a target cell s response to a hormone 影響賀爾蒙在作用細胞產生反應程度的因素 include the types of receptors 接受器的類型 in the target cell and the signal transduction mechanism 訊息傳遞機制 and the concentration of free hormone in the blood 血液中游離賀爾蒙的濃度 Control of Hormone Levels in Blood Transport of Hormones Hormone Interactions P156

28 Control of hormone levels in blood P158 The concentration of free hormone in the blood depends on three factors: the rate of hormone secretion 分泌速率, the amount of hormone transported bound to carrier proteins 與運送蛋白結合的量, and the rate at which the hormone is metabolized 被代謝的速率 In general, endocrine cells alter hormone secretion in response to two types of input, neural signals 神經的訊息 and humoral (blood-borne) signals 體液的訊息, each of which may be either stimulatory or inhibitory Neural signals directly regulate hormone secretion by the hypothalamus 下視丘, posterior pituitary gland 腦下腺後葉, and adrenal medulla 腎上腺髓質, which can affect the secretion of other hormones Copyright 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Cope with stress ( 對抗壓力 ) P159

29 Control of hormone levels in blood Humoral signals include three basic categories: hormones, ions 離子, and metabolites 代謝物 Hormonal control ( ) of hormone release with respect to tropic hormones of the hypothalamus and anterior pituitary and the negative feedback loops Many hormones regulate the blood concentrations of ions ( ) or metabolite ( ), which operate through negative feedback to regulate secretion of the hormones Many hormones are secreted according to a circadian rhythm: Hormonal control comes, at least partially, from melatonin The neural input is believed to come from an area of the hypothalamus called the suprachiasmatic nucleus 上叉核 which provides neural input (directly or indirectly) to the neurosecretory cells of the hypothalamus that secrete tropic hormones P

30 Metabolite Ion Copyright 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 6.12 Example of humoral control of hormone release. (a) Control of insulin 胰島素 release by blood glucose levels 血糖濃度. (b) Control of aldosterone 醛固酮 release by blood potassium levels 血鉀濃度. P159

31 Transport of hormones bound to carrier proteins Hydrophilic 親水性 hormones Peptides, catecholamines Dissolved in plasma Shorter half-life Hydrophobic 親脂性 hormones Steroids, thyroid hormones Bound to carrier proteins Only free hormone can bind to receptor Only free hormone can be metabolized Longer half-life P

32 Rate of Hormone Metabolism Sites of hormone metabolism 賀爾蒙代謝的位置 Target cell 作用細胞 hormone-receptor complex internalized 內化 by endocytosis 胞吞作用 degraded by enzymes 酵素分解 Blood 血液 brown down by enzyme Liver 肝臟 be metabolized by enzymes Lipophilic hormones can be bound to carrier proteins or stored in adipose tissue 脂肪組織 metabolized more slowly P

33 IV. Abnormal Secretion of Hormones Some disease conditions are caused by an excess in the secretion of a hormone 賀爾蒙分泌過量, termed hyper-secretion Growth hormone too much (in adults) acromegaly 肢端肥大症 Others are caused by too little secretion of a hormone 賀爾蒙分泌過少, termed hypo-secretion Insulin too little diabetes mellitus 糖尿病 In cases of hyper-secretion or hypo-secretion, the disease process can be primary 原發性 (acting directly in the endocrine gland) 直接因內分泌腺體異常所致 or secondary 續發性 (involving a problem with tropic hormone) 可能因腦下腺或下視丘異常, 造成 tropic hormone 的分泌異常所致 P160

34 Figure 6.13 Abnormal secretion of thyroid hormones. (a) Primary hypersecretion of thyroid hormones. An abnormality of the thyroid gland causes it to secrete too much of the thyroid hormones. Excess thyroid hormones in the blood induce strong negative feedback, decreasing TRH and TSH release into the blood. P161

35 Figure 6.13 Abnormal secretion of thyroid hormones. (b) An example of secondary hypersecretion of thyroid hormones. An abnormality 異常 of the anterior pituitary causes it to secrete too much TSH. Excess TSH in the blood stimulate the thyroid gland to secrete excess thyroid hormones. Negative feedback to the hypothalamus increases, so TRH levels in the blood decrease. P161

36 V. Hormone Interactions Antagonism 拮抗作用 : effects of two hormones oppose each other 作用相反 (1-1=0) insulin ( ) and glucagon ( ) on blood glucose 血糖 Additive 加成作用 : effects of two hormones favor each other and sum (1+1=2) epinephrine ( ) and norepinephrine ( ) on heart rate 心跳速率 (b 1 ) Synergism 協同作用 : effects of two hormones favor each other but the net effect exceeds the sum of individual effects (1+1>2) Glucagon ( ), cortisol ( ), and epinephrine ( ) on blood glucose Permissiveness 允許作用 : one hormone needed for another to exert its effects thyroid hormones cause expression 表現 of adrenergic receptors 腎上腺性接受器 in bronchiolar smooth muscle 細支氣管平滑肌 ; estrogen causes expression of progesterone receptors 黃體素接受器 in uterus 子宮 P