Endocrine System. School of Medicine, Zhejiang University 2017 年 5 月 27 日

Transcription

1 Endocrine System School of Medicine, Zhejiang University 2017 年 5 月 27 日

2 Introduction 1. Endocrine system: 1 Endocrine glands: 2 Endocrine tissue(clusters of cells ): pancreas islet, follicle, corpus luteum,et al 3 Endocrine cells: Amine precusor uptake and de-carboxylation cell(apud systems) Diffuse neuroendocrine system(dnes)

3 2. Features of the endocrine gland 1 typically arranged as cords /clusters/follicles 2 no ducts(ductless gland) 3 numerous Cap. 3

4 3.Function positive feedback(+) Endocrine system produce Hormones Act on target organs target cells negative feedback(-) What is hormone? Chemical messengers

5 1)Hormone classification 1 Nitrogenous-hormone --- Nitrogenous-hormone secreting cell Abundant RER and Golgi Abundant secretory granules Cytology is similar to serous cells 2 Steroid hormones --- Steroid-hormone secreting cell Abundant smooth ER Numerous mitochondria with tubular cristae( 嵴 ) Cytoplasmic lipid droplets 5

6 ultrastructure Nitrogenous hormone Steroid hormone 6

7 2)Hormones secretion Special secreting forms Autocrine Paracrine

8 Endocrine glands Thyroid gland Adrenal glands Pituitary gland

9 Thyroid gland ( 甲状腺 ) Two lobes connected by an isthmus( 峡部 ) Capsule: DCT Parenchyma: Follicles+LCT with cap. 9

10 1.Thyroid follicles Follicle: Colloid is surrounded by a single layer epithelium. Epithelium: Simple squamous (hypoactive), cuboidal or columnar (hyperactive), depending upon the functional status. Colloid - iodinated thyroglobulin 10

11 2.follicular cells EM: microvilli, RER, Golgi apparatus, secretory granules, lysosome, mitochondrion, endocytotic vesicles. Function: synthesize and release thyroid hormones: thyroxine (T4) and triiodothyronine (T3) 11

12 3.Synthesis/Storage/Secretion of TH a. tyrosine RER thyroglobulin (Gogi, glycosylated (G, secreting granules) colloid. b. iodination (iodide pump) iodide oxidation in cytoplasm colloid bound to tyrosine residues of thyroglobulin iodination thyroglobulin.

13 c. iodination thyroglobulin (TSH) endocytic vesicles LYS T3 & T4. blood

14 4. Function of T3, T4: a. Regulate the basal metabolic rate. b. influence the body growth and nervous system development during fetal life. c. Disorder: Hypothyroidism( 甲低 ) Hyperthyroidism( 甲亢 ) 14

15 Pathological state overproduction Thyroid hormone deficiency slows body hyperthyroidism processes: Clinical features: dry, puffy skin inability to keep warm weight gain a slow heart rate loss of energy and appetite constipation( 便秘 ) In adults, thyroid hormone underproduction A consequence of an increase in body s hypothyroidism metabolism: Clinical features: feeling hot increased sweating weight loss, with proximal muscle weakness rapaid heart rate anxiety and restless hyperactivity diarrhoea 腹泻 exophthalmic goiter myxoedema

16 Hypothyroidism Hypothyroidism present at birth: Mental retardation Short stature Coarse facial features Protruding tongue Umbilical hernia

17 5. Parafollicular cells( 滤泡旁细胞 ) ---single between follicular cells ---in small groups in interstitial tissue Also called calcitonin cell / C cell LM: ovoid, polygonal larger pale-stained argyrophilic granules Function: synthesize and release calcitonin, make blood calcium

18 Parathyroid glands ( 甲状旁腺 ) Overview Four small glands Posterior surface Capsule parathyroid 18

19 Parenchyma Chief cell: parathyroid hormone (PTH): make blood calcium Oxyphil cells: function is not known 19

20 Adrenal gland( 肾上腺 ) 20

21 Adrenal gland ---capsule: CT ---cortex: yellow, derived from mesoderm ---medulla: reddish-brown, derived from neural ectoderm

22 Adrenal gland cortex Zona glomerulosa Zona glomerulosa Zona fasciculata Zona fasciculata Zona reticularis Zona reticularis

23 Zona glomerulosa 15% of cortex volume ---Structure: LM cells : small, low columnar or polygonal, nuclei : deep stained, round cytoplasm : light basophilic ---Function: secrete mineralocorticoid ( eg. aldosterone): regulate electrolyte homeostasis and water balance

24 Zona fasciculata About 78% of cortex volume ---Structure: LM cells : large,light staining, appear vacuolated-empty, be arranged in straight cords. ---Function: secrete glucocorticosteroid (cortisol corticosterone) regulate carbohydrate, protein and lipid metabolism influence immune response

25 Zona reticularis 7% of cortex volume ---Structure: LM cells: polyhedral and small; be arranged in irregular anastomosing cords cytoplasm: acidophilic ---Function: secret androgen(testosterone) and small amount of oestrogen

26 Adrenal medulla ---Structure: ---medullary cell ( chromaffin cell ) : LM: cells: polyhedral, be arranged in nests or short cords cytoplasm: weakly basophilic, brownish granules- when fixed by bichromate-containing fixative. ---central vein ---ganglial cells: multipolar neurons large, 2~3 in groups

27 ---medullary cell ( chromaffin cell ) Noradr. cell EM electron-dense granules adrenaline cell: 80% i. heart rate ii. dilate blood vessel Adr. cell noradrenaline cell: 20% i. blood pressure ii. the flow speed of blood ---Function: secrete adrenaline and noradrenaline secrete some polypeptides(galanin, neuropeptide Y, enkephalin)

28 Pathological state Excessive adrenal secretion of glucocorticoid hormones Cushing s syndrome ( 库欣综合征 )

29 Hypophysis (Pituitary) General Features Pea-sized Sits in the sella turcica Compound gland Attaches to the hypothalamus by the pituitary stalk (infundibulum) Two Lobes: (1) adenohypophysis; (2) neurohypophysis 29

30 Pituitary gland( 脑垂体 ) Adenohypophysis Pars Distalis ( 远侧部 ) Pars intermedia ( 中间部 ) Pars Tuberalis ( 结节部 ) Neurohypophysis Pars nervosa ( 神经部 ) Infundibulum ( 漏斗 ) 30

31 Pars Distalis ( 远侧部 ) Glandular cells are arranged in nests Rich in capillaries around the cells Cell Classification: Chromophobes ( 嫌色细胞 ) Chromophils ( 嗜色细胞 ) Distinct 3 Type Cells A --- Acidophil round or oval, eosinophilic stainning B --- Basophil Less, large cell, ovoid or polygonal basophilic granules C --- Chromophobe more, small, pale, no clear boundary 31

32 1. Chromophils: Acidophils: ⑴Somatotrophs: somatotropin (growth hormone,gh) ⑵Mammotrophs: prolactin (PRL) Basophils: 2. Chromophobes: ⑴Corticotrophs: adrenocorticotropic hormone (ACTH) ⑵Thurotrophs: thyroid stimulating hormone (TSH) ⑶Gonadotrophs: follicle-stimulating hormone (FSH)

33 Pathological state Growth hormone in kids deficient too much Dwarfism Gigantism

34 Pars Intermedia ( 中间部 ) Colloid-containing cysts Basophilic cells Melanocyte-stimulating hormone (MSH) Pars Tuberalis ( 结节部 ) Cells arranged in cords May secrete FSH and LH, but has not been confirmed 34

35 Hypophyseal portal system 垂体门脉系统 Superior hypophyseal artery (Primary plexus)capillaries Hypophyseal portal vein (Secondary plexus) capillaries Hypophyseal vein

36 Relationship between hypothalamus and adenohypophysis arcuate nucleus secrete releasing hormones (RH) ---GRH, PRH, TRH, GnRH, CRH, MSRH secrete release inhibiting hormones (RIH) ---SOM, PIH, MSIH

37 Relationship between hypothalamus and neurohypophysis Supraoptic nucleus Paraventricular nucleus 37

38 Neurohypophysis ( 神经垂体 ) Pars nervosa Components Pituicytes ( glial cells) Capillaries (fenestrated) Unmyelinated nerve fibers Function: Store and release oxytocin and antidiuretic hormone (ADH)/vasopressin ( 血管升压素 )

39 Neurohypophysis ( 神经垂体 ) Herring bodies: Neurosecretory granules accumulate in the dilated portions of the axons near their terminals. LM: acidophilic, irregular structure

40 Hypothalamus /hypophysis/endocrine gland

41 Pineal Gland( 松果体 ) Responds to light transmitted to the cerebral cortex Melatonin (at night) 41

42 KEY POINTS General structure of endocrine gland and endocrine cells Histological structure and function of the thyroid gland, adrenal gland, hypophysis Composition and function of the hypophyseal portal system Structure and function relationship between the hypothalamus and the hypophysis

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