Download Chapter 6 The endocrine system

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
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
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Endocrine organs
松果腺
下視丘
腦下腺
甲狀腺
副甲狀腺
胸腺
心臟
腎上腺
胰臟
胃
肝臟
腎臟
卵巢
小腸
睪丸
皮膚
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.
Figure 6.1 Endocrine organs.
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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
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
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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.
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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
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Education, Inc., publishing as
Benjamin Cummings.
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Blood connection between hypothalamus and
anterior pituitary
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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
微血管床
they effect release of anterior pituitary
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
動脈
門脈靜脈
靜脈
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 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
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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
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
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Tropic hormones of the hypothalamus and anterior pituitary
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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.
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)
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短的負回饋路徑
長的負回饋路徑
 The multistep pathways by which
hypothalamic and anterior
pituitary tropic hormones are
produced are regulated by
feedback loops 回饋路徑
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Figure 6.6 Negative feedback
loops affecting hypothalamic
and anterior pituitary
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hormones.
 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)
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Figure 6.7 Regulation of
thyroid hormone release.
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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
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Benjamin Cummings.
Figure 6.2 Hypothalamus and
pituitary gland.
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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 (T4) and triiodiothyronine (T3),
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
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咽
喉嚨
甲狀腺
副甲狀腺
頸動脈
氣管
前面 (腹面)
食道
後面 (背面)
Figure 6.8 Locations of the thyroid and parathyroid glands.
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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.
咽
喉嚨
甲狀腺
副甲狀腺
頸動脈
氣管
前面 (腹面)
食道
後面 (背面)
Figure 6.8 Locations of the thyroid and parathyroid glands.
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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
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.
 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
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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
絲狀區
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.
束狀區
皮質
網狀區
髓質
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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
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Pancreas
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.
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.
 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
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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
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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 D3)
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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
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Control of hormone levels in blood

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
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publishing as Benjamin Cummings.
Cope with stress
(對抗壓力)
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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
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Metabolite
Ion
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P159
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.
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
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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
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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
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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.
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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.
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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 (b1)
 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
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