Lecture 7   General medicine_3rd semester MICROSCOPIC STRUCTURE, HISTOPHYSIOLOGY AND DEVELOPMENT OF ENDOCRINE GLANDS   Hor...
<ul><li>h ormones  =  chemical signals used for communication between cells </li></ul><ul><li>more than 60  hormones class...
Endocrine  glands (glandulae sine ductibus) -  have no ducts - have exceptionally rich blood supply - secrete hormones  th...
Hypo physis (hypophysis cerebri,  glandula pituitaria ) <ul><li>sella turcica  </li></ul><ul><li>0.6 – 0.7 g </li></ul><ul...
Blood supply: direct arterial supply has only neurohypophysis (from two sets of vessels -  superior hypophyseal arteries  ...
Pars distalis  is made up of cords of glandular cells among them  are blood sinusoids Cells of the pars distalis: - chromo...
 
 
Acidophils somatotropic  cells   lactotropic  cells   by immunohistochemistry: Basophils adrenocorticotropic cells   thyro...
Pars intermedia  consists of small cystic cavities (residua of Rathke´s pouch  that  are limited by basophilic and chromop...
<ul><li>Pars tuberalis  </li></ul><ul><li>surrounds  infundibul ar stem, 25 – 60   m thick,  is highly vascularized and c...
Pars nervosa
Infundibular stem: cca 100 000 neurites of nerve cells hypothalamic nuclei  (tr. hypothalamohypophysealis) ncl. supraoptic...
Development of the hypophysis
Epi physis   - pineal gland ( corpus pineale ) 0.1 – 0.2 g is of cone-shaped form, 5-8 x 5-5 mm enveloped by a thin  capsu...
 
 
Development of the pineal gland
<ul><li>Glandula thyreoidea  (thyroid gland) </li></ul><ul><li>25 – 40 g </li></ul><ul><li>in the anterior of the neck, be...
Follicles follicular cells
 
 
parafollicular cells
 
Development of the  thyroid gland The thyroid gland is the first of the endocrine glands to develop in the embryo. 24 days...
 
Development of the  thyroid gland
<ul><li>Glandulae parathyreoideae  (parathyroid glands) </li></ul><ul><li>2  p aired oval bodies cca  6  -8  mm  long  </l...
chief cells
oxyphil cells
Development of parathyroid bodies Parathyroide glands derive from the endoderm of third (inferior) and fourth (superior) p...
Development of parathyroid bodies
G landula suprarenalis   (suprarenal gland, adrenal gland) paired gland situated at upper pole of each kidney   the right ...
A schema of the adrenal gland
The adrenal cortex: is composed of cord of glandular cells separated  by blood sinusoids according  to the arrangement of ...
 
Zona glomerulosa: Is located immediatly under the capsule ; glandular cords are arranged in rounded clusters and curved co...
The adrenal medulla composed of large round or polyhedral cells arranged in clumps or short cords surrounded with framewor...
Blood supply of the  adrenal gland
Development of the adrenal gland
 
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Lect7 endocrine sy

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  • The pituitary gland secretes hormones regulating homeostasis , including tropic hormones that stimulate other endocrine glands . It is functionally connected to the hypothalamus by the median eminence and thereby it´s they highest integral system between. AUTONOMIC NERVOUS SYSTEM and ENDOCRINE SYSTEM …..
  • It is best known for its roles in female reproduction: it is released in large amounts after distension of the cervix and vagina during labor, and after stimulation of the nipples , facilitating birth and breastfeeding , respectively. Recent studies have begun to investigate oxytocin&apos;s role in various behaviors, including orgasm , social recognition, pair bonding , anxiety, trust, love , and maternal behaviors. [1]
  • The thyroid is one of the largest endocrine glands in the body. The thyroid controls how quickly the body uses energy, makes proteins , and controls how sensitive the body should be to other hormones . Calcitonin is a 32-amino acid linear polypeptide hormone that is produced in humans primarily by the parafollicular cells (also known as C-cells) of the thyroid , and in many other animals in the ultimobranchial body . [2] It acts to reduce blood calcium (Ca 2+ ), opposing the effects of parathyroid hormone (PTH). [3]
  • oxy phil cells can be found in clusters in the center of the section and at the periphery.Oxyphil cells appear at the onset of puberty, but have no known function
  • Parathyroide glands derive from the endoderm of third (inferior) and fourth (superior) pharyngeal pouches.
  • Zona glomerulosa: Is located immediatly under the capsule ; glandular cords are arranged in rounded clusters and curved columns. The cells are supposed to secrete MINERALOCORTICOIDS, from which aldosterone is the most potent..........15% Zona fasiculata: Constitute the middle layer of the cortex in which the glandular cords are parallel to each other but perpendicular to the capsule. The zona fasiculata cells produce GLUCOCORTOCOIDS, which influence the on the carbohydrate metabolism. Hydrocortisone is the mot famous one and important substance of them. Zona reticularis: It is situated cloesest to the medulla and is composed of rounded cells arranged into branching and anastomosing cords or columns. Cells of the zona reticularis secrete small amounts of sex steroids .
  • Widespread sympathetic respons!!
  • Lect7 endocrine sy

    1. 1. Lecture 7 General medicine_3rd semester MICROSCOPIC STRUCTURE, HISTOPHYSIOLOGY AND DEVELOPMENT OF ENDOCRINE GLANDS Hormones – classification Components of the endocrine system Principles of humoral regulation
    2. 2. <ul><li>h ormones = chemical signals used for communication between cells </li></ul><ul><li>more than 60 hormones classified as </li></ul><ul><li>amino acids analogues and derivatives </li></ul><ul><li>peptide or protein hormones </li></ul><ul><li>steroid hormones </li></ul><ul><li>receptors are chemically defined sites bound with cell membranes </li></ul><ul><li>Endocrine system consists of </li></ul><ul><li>- endocrine glands - hypophysis, pineal, thyroid, parathyroid, and adrenal </li></ul><ul><li>- endocrine cell groups in glands with exocrine or other function s (islets of Langerhans in the pancreas, Leydig cells in testes, granulosa cells in ovaries, juxtaglomerular apparatus of kidneys, trophoblast cells of the placenta </li></ul><ul><li>- cells with endocrine function that are scattered in nonglandular organs (as a gut, stomach, trachea, etc.) - e.g. GEP cells </li></ul>
    3. 3. Endocrine glands (glandulae sine ductibus) - have no ducts - have exceptionally rich blood supply - secrete hormones that pass into the circulatory system and induce a response of specific target cells, tissues, or organs <ul><li>h ypophysis </li></ul><ul><li>epiphysis </li></ul><ul><li>thyroid gland </li></ul><ul><li>parathyroid gland </li></ul><ul><li>adrenal gland </li></ul><ul><li>islets of Langerhans </li></ul>
    4. 4. Hypo physis (hypophysis cerebri, glandula pituitaria ) <ul><li>sella turcica </li></ul><ul><li>0.6 – 0.7 g </li></ul><ul><li>adenohypophysis: pars distalis (75 %) </li></ul><ul><li>(anterior lobe) pars intermedia </li></ul><ul><li> pars tuberalis </li></ul><ul><li>neurohypophysis: infundibulum (infundibular stem) </li></ul><ul><li>(posterior lobe) pars nervosa </li></ul>lobes are enveloped by a thin common connective tissue capsule , from which delicate septa with blood vessels and nerves project into the parenchyma
    5. 5. Blood supply: direct arterial supply has only neurohypophysis (from two sets of vessels - superior hypophyseal arteries and inferior hypophyseal arteries ). The adenohypophysis is drained by hypophyseal portal veins , which arise from the primary capillary plexus in the region of the median eminence and infundibular stem
    6. 6. Pars distalis is made up of cords of glandular cells among them are blood sinusoids Cells of the pars distalis: - chromophobic cells -10-15% - chromophilic cells – acidophilic cells - 50 % – basophilic cells
    7. 9. Acidophils somatotropic cells lactotropic cells by immunohistochemistry: Basophils adrenocorticotropic cells thyrotropic cells gonadotropicFSH cells gonadotropic LH cells
    8. 10. Pars intermedia consists of small cystic cavities (residua of Rathke´s pouch that are limited by basophilic and chromophobic cells ; basophils produce MSH - melanocyte-stimulating hormone (in amphibians) - in the human its function is unclear
    9. 11. <ul><li>Pars tuberalis </li></ul><ul><li>surrounds infundibul ar stem, 25 – 60  m thick, is highly vascularized and composed of clusters of basophils and chromophobic cells; basophils are supposed to secrete gonadotropic hormones (FSH, LH) </li></ul><ul><li>Neurohypophysis (posterior lobe) </li></ul><ul><li>composed of pars nervosa and infundibular stem </li></ul><ul><li>The pars nervosa: </li></ul><ul><li>- pituicytes - irregular-shaped cells with numerous processes </li></ul><ul><li>- axoterminals and nonmyelinized nerve fibers (whose cell bodies are in the hypothalamus ( nc. supraopticus, nc. paraventricularis, nc. tuberalis ) </li></ul><ul><li>fenestrated capillaries </li></ul><ul><li>Function: </li></ul><ul><li>release site of hormones: </li></ul><ul><li>ADH (va s opre s sin) </li></ul><ul><li>oxytocin </li></ul><ul><li>synthetized by ne rve cell bodies and </li></ul><ul><li>are transported by axons in the </li></ul><ul><li>infundibular stem or pars nervosa </li></ul><ul><li>neurosecretion </li></ul><ul><li>are seen at preaxoterminal sites as </li></ul><ul><li>Herring´s bodies </li></ul>
    10. 12. Pars nervosa
    11. 13. Infundibular stem: cca 100 000 neurites of nerve cells hypothalamic nuclei (tr. hypothalamohypophysealis) ncl. supraopticus a ncl. paraventricularis (large neurons) ncl. tuberales (nc.hypothalamicus ventromedialis et dorsomedialis, ncl. infundibularis) - small neurons axoterminals end near capillaries of the primary capillary plexus hypothalamic regulatory factors (inhibins and liberins) are transported via vv. portae hypophysis to the pars distalis
    12. 14. Development of the hypophysis
    13. 15. Epi physis - pineal gland ( corpus pineale ) 0.1 – 0.2 g is of cone-shaped form, 5-8 x 5-5 mm enveloped by a thin capsule with delicate septae dividing the parenchyma into lobules They consist of two cell types: - pinealocytes - They produce and secrete melatonin . They are also in majority and arranged in clumps or clusters; the cells are characterized by lobulated nucleus, prominent nucleoli, and membrane-bound granules in the cytoplasm - interstitial cells - about 5 % (modified astrocytes of fibrilar type) and - non-myelinized nerve fibres and blood capillary plexus Pineal gland of adults contains the calcified concretions called as brain sand or acervulus cerebri (corpora arenacea). The concretions differ from their surrounding by deep staining and concentric appearance Hormone: melatonin - inhibits steroidogenic activity of endocrine cells in gonads + r egulating the circadian rhythms of several biological functions
    14. 18. Development of the pineal gland
    15. 19. <ul><li>Glandula thyreoidea (thyroid gland) </li></ul><ul><li>25 – 40 g </li></ul><ul><li>in the anterior of the neck, below the cricoid cart. </li></ul><ul><li>2 lobes + isthmus </li></ul><ul><li>in  50 % of cases the pyramidal lobe ( lobus pyramidalis ) is </li></ul><ul><li>found; it exits from the isthmu s cranially </li></ul><ul><li>connective tissue capsule + sep t ae </li></ul><ul><li>the parenchyma organized into the lobules </li></ul><ul><li>lobules are composed of the follicles , which </li></ul><ul><li>vary considerably in diameter and contain </li></ul><ul><li>gelatinous material   called the colloid </li></ul><ul><li>the walls of follicles consist of simple epithelium </li></ul><ul><li>that rests on a thin basal lamina and delicate </li></ul><ul><li>reticular network </li></ul><ul><li>the epithelium involves mainly follicular cells , </li></ul><ul><li>which are squamous to columnar in dependance on the functional status </li></ul><ul><li>the cells produce colloid ; it consists of mucoproteins, proteolytic enzymes and a </li></ul><ul><li>glycoprotein called thyroglobulin – primary storage form of thyroid hormone </li></ul><ul><li>triiodothyronine (T3) + tetraiodothyronine (thyroxin, T4) </li></ul><ul><li>p arafo licular, light or C – cells (lie immediately adjacent to basal lamina) - calcitonin </li></ul>
    16. 20. Follicles follicular cells
    17. 23. parafollicular cells
    18. 25. Development of the thyroid gland The thyroid gland is the first of the endocrine glands to develop in the embryo. 24 days after fertilization. It is derived from the ventral wall of the embryonic pharanx at the site just caudal to the future tounge bud. Here a small thickening early occurs, thyroid primordium (solid mass of endodermal cells.). As the tounge grows the thyroid diverticulum descends down in the neck and is later provided with a lumen; the thyroglossal duct . It becomes solid and the blind end then divides into 2 lobules (right and left) which are connected by an isthmus. By 7th week thyroid gland reaches its final state + definitive position in the neck. and thyroglossal duct normally dissapears except for the proximal part – foramen Caecum and caudal part – from which the pyramidal lobe develops (in about 50 procent of the cases)
    19. 27. Development of the thyroid gland
    20. 28. <ul><li>Glandulae parathyreoideae (parathyroid glands) </li></ul><ul><li>2 p aired oval bodies cca 6 -8  mm long </li></ul><ul><li>and 2-5 mm wide </li></ul><ul><li>lie on the dorsal aspects of both </li></ul><ul><li>lobes of the thyroid </li></ul><ul><li>weight of bodies is 0.2 g altogether </li></ul><ul><li>thin connective tissue capsule </li></ul><ul><li>delicate septae that divide gland into </li></ul><ul><li>small lobules </li></ul><ul><li>they are composed of closely packed groups </li></ul><ul><li>or cords of glandular cells that are of two </li></ul><ul><li>types: </li></ul><ul><li>c h ief (principal) cells </li></ul><ul><li>numerous, 8-10 diameter, large accumulations of glycogen and lipid droplets </li></ul><ul><li>cells secrete parathyroide hormone (PTH) – regulate calcium level of the blood </li></ul><ul><li>PTH is essencial for life (tetany) , antagonist to calciotonin(parafollicular cells) </li></ul><ul><li>oxy phil cells </li></ul><ul><li>occur singly or in groups, are larger than chief cells, stain intensely with eosin, </li></ul><ul><li>contain elongated mitochondia with numerous cristae </li></ul><ul><li>cells increase in number after puberty </li></ul>
    21. 29. chief cells
    22. 30. oxyphil cells
    23. 31. Development of parathyroid bodies Parathyroide glands derive from the endoderm of third (inferior) and fourth (superior) pharyngeal pouches.
    24. 32. Development of parathyroid bodies
    25. 33. G landula suprarenalis (suprarenal gland, adrenal gland) paired gland situated at upper pole of each kidney the right is triangular the left semilunar weight of 5 – 7 g capsule cortex – 80 % medulla
    26. 34. A schema of the adrenal gland
    27. 35. The adrenal cortex: is composed of cord of glandular cells separated by blood sinusoids according to the arrangement of cells in cords - 3 layers of the cortex are distinguished zona glomerulosa zona fasciculata zona reticularis
    28. 37. Zona glomerulosa: Is located immediatly under the capsule ; glandular cords are arranged in rounded clusters and curved columns. The cells are supposed to secrete MINERALOCORTICOIDS, from which aldosterone is the most potent..........15% Zona fasiculata: Constitute the middle layer of the cortex in which the glandular cords are parallel to each other but perpendicular to the capsule. The zona fasiculata cells produce GLUCOCORTOCOIDS, which influence the on the carbohydrate metabolism. Hydrocortisone is the mot famous one and important substance of them. Zona reticularis: It is situated cloesest to the medulla and is composed of rounded cells arranged into branching and anastomosing cords or columns. Cells of the zona reticularis secrete small amounts of sex steroids .
    29. 38. The adrenal medulla composed of large round or polyhedral cells arranged in clumps or short cords surrounded with framework of reticular fibers, containing numerous capillaries with fenestrae,venules, nerve fibers and solitary sympathetic neurones glandular cells called as chromaffin cells contain fine granular cytoplasm and secrete catecholamines <ul><li>2 types of chromaffin cells: </li></ul><ul><li>secreting adrenalin or epinephrine (most - 96%) </li></ul><ul><li>secreting noradrenalin or norepinephrine (the rest) </li></ul>
    30. 39. Blood supply of the adrenal gland
    31. 40. Development of the adrenal gland
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