Endocrine System

下丘脑 人体内分泌系统的分布 松果体 脑垂体 甲状旁腺 甲状腺 甲状腺 胰腺的胰岛 肾上腺 卵巢的黄体 睾丸中的间质细胞

1.       Components: ---small gland or endocrine cell: islet of pancreas and corpus luteum ---endocrine gland: Thyroid gland Parathyroid gland Adrenal gland Pituitary gland(hypophysis) Pineal body

2.    General structure ---capsule: CT ---parenchyma: endocrine cells arranged into nest, cord, cluster or follicle, secrete hormones ---interstitium: CT, rich in capillaries

3. Characteristics of endocrine glands: A. Ductless. Cells are arranged in cord, follicle, aggregation or net-like structure, among them are spaces containing rich blood and lymph Caps.

B. Secrete hormone at a specific time and in small amounts, which act on target organ, tissue or cells. C. The secretion activity is often regulated by other hormones or nerve impulses. D. Make up an endocrine organ, or exist in other organs as tissue or dispersed cells.

E. Two types of endocrine cells: 1. Peptide-secreting cells: Well developed G, RER and secreting granules. Release hormone that chemically contains amino acids.

2. Steroid-secreting cells: Foamy cytoplasmic appearance under LM 2. Steroid-secreting cells: Foamy cytoplasmic appearance under LM. Rich in SER, lipid droplets andMT containing tubular-like cristae. Secrete hormone that chemically contains steroids.

内分泌腺的结构特点 ①无导管 ②细胞排列成团、索、滤泡状 ③毛细血管丰富（有孔型、血窦）

激素（Hormone） 荷尔蒙 receptor paracrine 作用机理 与受体结合，引发细胞反应。 作用特点 特异性； 高效性； 交叉性； 远距离作用和旁分泌 paracrine 性质分类 含氮激素和类固醇激素

激素的两种化学类型 受体在膜上 含氮激素 受体在细胞内 类固醇激素

两种内分泌细胞的比较 类型 细胞特点 分布 分泌含氮激素细胞 rER、Golgi丰富，有膜包分泌颗粒 类型　 细胞特点 分布 分泌含氮激素细胞 rER、Golgi丰富，有膜包分泌颗粒　　　 甲状腺、甲状旁腺、垂体、肾上腺髓质、APUD系统 分泌类固醇激素细胞 sER丰富、mit嵴管状或管泡状、脂滴多 肾上腺皮质，睾丸间质、黄体

内分泌细胞的超微结构特点： 类固醇激素分泌细胞 含氮激素分泌细胞

两种线粒体 板状嵴线粒体 管状嵴线粒体

Thyroid gland ---largest endocrine gland, 15-40g ---two-lobes, connect to each other by isthmus

甲状软骨 甲状腺

A. General structure: Fibrous capsule protrudes and divides the parenchyma into lobules containing follicles and rich capillaries. B. Follicle: Colloid is surrounded by singer layer epithelium. 1. Epithelium: Simple squamous (hypoactive), cuboidal or columnar (hyperactive), depending upon the functional status.

Epithelial cell has rich RER, G, secreting granules, microvilli, phagosomes, LYS, iodide pump, and receptors for thyrotropin (TSH).

2. Colloid: Homogeneous secretion of epithelium 2. Colloid: Homogeneous secretion of epithelium. Acidophilic and PAS (+). Contains iodated thyroglobulin. 3. Formation of triiodothyronine (T3) & tetraiodothyronine (T4): a. AA→ (RER)→ thyroglobulin → (G, secreting granules) → colloid. b. Iodide → (iodide pump) → iodide oxidation in cytoplasm → colloid → bound to tyrosine residues of thyroglobulin → iodated thyroglobulin.

激素的合成和分泌 碘化甲状腺球蛋白 碘活化 I 2O 溶酶体 分泌小泡 胶质小泡 合成甲状腺球蛋白 摄碘 I - 摄取氨基酸 Ｔ3 Ｔ4

c. iodated thyroglobulin → (TSH, microvilli) → phagosomes → LYS → T3 & T4. 3. Modulation of T3, T4 secretion: hypothalamus-pituitary-thyroid axis. 4. Function of T3, T4: a. elevates the basal metabolic rate. b. influence the body growth and nervous system development during fetal life. Cretins: Arrested mental and physical development in adult because of hypothyroid from birth.

外界因子作用 主要是抑制碘的吸收、转运和浓缩和活化各个过程. 高碘 遗传与免疫 过氧化物酶、去卤化酶的缺陷及碘酪氨酸偶联缺陷等. 外界因子作用　 主要是抑制碘的吸收、转运和浓缩和活化各个过程. 高碘　 过氧化物酶的功能过多的被占用，影响酪氨 酸氧化，因而碘的有机化过程受阻，甲状腺代偿性肿大. 遗传与免疫 过氧化物酶、去卤化酶的缺陷及碘酪氨酸偶联缺陷等.

克汀病或呆小症（cretinism） 　　由于地方性缺碘，在胎儿和婴儿期从母体获得或合成甲状腺素不足或缺乏，导致生长发育障碍，表现为大脑发育不全、智力低下、表情痴呆，骨形成及成熟障碍，四肢短小，形成侏儒。

甲状腺机能亢进：甲状腺素合成和分泌过多 甲状腺对称弥漫肿大 突眼

甲状腺机能减退 长期缺碘甲状激素合成不足 呆小症

成龙赴台湾宣传新片 承认自己患甲状腺肿瘤

异常 我有甲亢 甲状腺机能低下（甲低）： 小儿－－呆小症 成人－－粘液性水肿 甲状腺机能亢进（甲亢）: 爱出汗可突眼脾气增大苦难言 心发慌手发抖食欲增加人消瘦 甲状腺机能低下（甲低）： 小儿－－呆小症 成人－－粘液性水肿 甲状腺机能亢进（甲亢）:

C. LCT around follicles: Rich in capillaries. Parafollicular cells: C cells. Situated often in groups among follicles, or among follicular epithelium cells but are not adjacent to colloid. Argyrophilic. Lightly stained.

滤泡旁细胞 HE染色 镀银染色

Contain rich RER and secretory granules Contain rich RER and secretory granules. Secrete calcitonin, which can decrease the blood Ca2+ level by inhibiting the activity of osteoclasts.

Adrenal gland ---paired, situated on the upper poles of kidney ---capsule: CT ---cortex: yellow, derived from mesoderm ---medulla: reddish-brown, derived from neuroectoderm

Adrenal gland: Centrally located medulla is derived from ectoderm and surrounded by mesoderm-derived cortex and fibrous capsule. A. Cortex: 3 layers are not sharply defined. Cells produce and release steroid-like hormone only upon demand.

1. Zona glomerulosa: Cells are arranged in clusters beneath the capsule. The secretion, the mineralocorticoids (e.g. aldosterone), participates in electrolyte balance regulation. Its secretion activity is regulated by renin-angiotensin system.

2. Zona fasciculata: Constitutes about 65% of cortex 2. Zona fasciculata: Constitutes about 65% of cortex. The typical steroid-secreting cells in the body are arranged in straight cords, and run perpendicularly to the capsule, with rich Caps among them.

Their glucocorticoids release (e. g Their glucocorticoids release (e.g. Cortisol & Corticosterone), which is regulated by ACTH, influences the protein, fat and carbohydrate metabolism, and impairs the immune responses.

3. Zona reticularis: Adjacent to medulla with obscure outline 3. Zona reticularis: Adjacent to medulla with obscure outline. Cells are arranged in net-like structure and contain more lipofuscin pigment granules.

Their androgen (with small amount of estrogen & glucocorticoids) release, which is regulated by ACTH, influences the sexual development.

B. Medulla: Contains central vein and sympathetic ganglion B. Medulla: Contains central vein and sympathetic ganglion. Two types of cells, which are also called chromaffin cells because the chromaffic granules can be found in their cytoplasm when fixed by chromaffic salt, are arranged in cords or clusters, among them exist capillaries.

Epinephrine-secreting cells and norepinephrine-secreting cells secrete adrenaline/epinephrine and noradrenaline/norepinephrine, respectively. The cytoplasm granules in former cells are smaller and slightly stained.

Adrenal medulla ①     medullary cell: chromaffin cell ---structure: LM: /polyhedral, cord /brownish cytoplasm granules- when fixed by bichromate-containing fixative

EM: /electron-dense granules: adrenaline cell: 80% i.    increase the heart rate ii.   dilate BV noradrenaline cell: 20% i.    increase blood pressure ii.   increase the flow speed of blood

Function: i.    secrete adrenaline and noradrenaline ii.  secrete some polypeptides(galanin, neuropeptide Y, enkephalin) ② ganglial cell: polypolar neurons- large, 2-3 in groups ③ central vein

(EM) 肾上腺素细胞 去甲肾上腺素细胞 肾上腺素 去甲肾上腺素 心率加快，心血管扩张 血压增高，血流加快

The hormones, the adrenaline and noradrenaline, which are stored in granules and whose secretion is stimulated by innervating sympathetic nerve, can immediately elevate the heart beating rate and blood pressure, respectively.

Pituitary gland hypophysis

Pituitary gland ---ovoid, flattened organ, 0.5X1X1cm, 0.5g in weight, in pituitary fossa of sphenoid bone ---capsule: CT ---adenohypophysis: the pars distalis the pars intermedia the par tuberalis ---neurohypophysis: the pars nervosa infundibular stalk

Pituitary gland: Most important endocrine gland. A. General structure: 1. Adenohypophysis: pars distalis (anterior lobe) + pars tuberalis + pars intermedia. 2. Neurohypophysis: pars nervosa (constitute the posterior lobe, together with pars intermedia) + infundibulum.

B. Adenohypophysis: 1. Pars distalis: Aggregated cells are surrounded by sinusoidal Caps, the secondary Cap network of hypophyseal portal circulation. a. acidophilic cell: 40%. Contains acidophilic secreting granules. The secretions are peptides. 2 types: * somatotrophic cell: secretes somototropin (GH), which can stimulate the growth of bone, muscles and CT, etc. Lack of GH in childhood results in midget. * mammotrophic cell: secretes prolactin, which can stimulate the development of mammary glands.

其实所有身高超过2米10以上的人都存在着出现这种病症的危险，姚明也曾经处于“腺脑垂体分泌生长激素过多症”的威胁，但是他在身体尚未完全发育好的时候，已经采用了当时最先进的药物控制，所以现在已经基本上不需要再担心。

垂体前叶功能低下： 　　垂体性侏儒症（pituitary dwarfism）：指因垂体前叶分泌生长激素部分或完全缺乏所致儿童期生长发育障碍性疾病，表现为骨骼躯体生长发育迟缓，体型停滞于儿童期，身材矮小，皮肤和颜面可有皱纹，常伴性器官发育障碍，但智力发育正常。

b. basophilic cell: 10%. Larger, contains basophilic and PAS (+) secreting granules. The secretions are glycoproteins. 3 types: * thyrotropic cell: secretes thyrotropin (TSH). * corticotropic cell: secretes corticotropin (ACTH) * gonadotropic cell: secretes gonadotropin, which includes follicle-stimulating hormone (FSH) that can stimulate the formation of oocyte and sperm, and luteinizing hormone (LH) that can stimulate the release of sex hormone. c. chromophobe: 50%. Smaller and inactive.

2. Pars intermedia: Contains follicles. Functions unknown. 3. Pars tuberalis: Secretes gonadotropin. C. Neurohypophysis: 1. Pars nervosa: a. pituicytes: specific glial cells.

b. unmyelinated nerve fibers: are the axons of neurons, whose cell bodies locate in paraventricular and supraoptic nuclei in hypothalamus. The axon dilations, the Herring Bodies, are light acidophilic and contain many secretory granules occupied by peptide-containing hormone. The oxytocin, which is produced by paraventricular nuclei, can shrink smooth muscles in uterus when parturition. The antidiuretic hormone (ADH, vasopressin), which is produced by supraoptic nuclei, can facilitate water re-absorption in kidney.

2. Infundibulum: Composed of median eminence and neural stalk. Contains primary Cap network of hypophyseal portal circulation.

D. Regulation of hormone release in pars distalis: a. the neuroendocrine cells in hypothalamus and endocrine cells in pituitary are functionally connected by hypophyseal portal circulation.

视上核和室旁核 弓状核 下丘脑神经垂体束 下丘脑腺垂体束 垂体门微静脉 第一级cap网 第二级cap网 赫令体 神 腺

The neurons in tuberal nuclei in hypothalamus can produce releasing and inhibiting hormone, which are released into the infudibulum, where the primary Cap network of hypophyseal portal circulation exists. b. positive and negative feedback.

弥散神经内分泌系统 1、摄取胺前体脱羧细胞（APUD细胞）：含胺或具有摄取胺前体，细胞内脱羧，产生胺和或肽的细胞，分布于内脏 2、DNES系统（弥散神经内分泌系统）： 指：具有内分泌功能的神经细胞和散在的内分泌细胞 分 中枢：下丘脑、垂体的某些细胞、松果体 周围：胃、肠、胰、呼吸道、泌尿生殖道 细胞、甲状旁腺主细胞等