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Endocrine glands Endocrine glands 1. Endocrine glands overview 2. Pituitary gland, hypophysis cerebri 3. Pineal gland, epiphysis cerebri 4. Thyroid gland. Parathyroid glands 5. Suprarenal (adrenal) glands. Paraganglia 6. Endocrine pancreas – islets of Langerhans 7. Gonads

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Endocrine glandsEndocrine glands

1. Endocrine glands overview

2. Pituitary gland, hypophysis cerebri

3. Pineal gland, epiphysis cerebri

4. Thyroid gland. Parathyroid glands

5. Suprarenal (adrenal) glands. Paraganglia

6. Endocrine pancreas – islets of Langerhans

7. Gonads

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Endocrine systemEndocrine system�� Endocrine glandsEndocrine glands::

� work parallel (in concert) with the immune and nervous systems

� neurohumoral regulation of body functions

� Anatomical peculiaritiespeculiarities::� do not have excretory ducts (ductless),

glandulae sine ductibus (PNA)

� secrete hormones directly into the blood� highly vascularized

� surrounded with a dense network of fenestrated capillaries

� produce small amounts of hormonesacting on distant target tissues

�� Chemical nature of hormones:Chemical nature of hormones:� amino acid-derived hormones� peptide hormones – secretory granules

o small proteinso glycoproteins

� lipid derivatives� steroid hormones – cholesterol� eicosanoids – prostaglandins

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ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Endocrine glandsEndocrine glands

33

�� Endocrine cellsEndocrine cells::� aggregated asas distinctdistinct endocrineendocrine glandsglands:

� pituitary gland� pineal gland� thyroid gland� parathyroid glands� adrenal glands

�� a distinct part of certain organsa distinct part of certain organs:� islets of Langerhans in the pancreas� collection of cells in:

o hypothalamuso testis (Leydig cells)o ovary – follicular and theca cells

�� single endocrine cellssingle endocrine cells – paracrine signaling

� intestinal enteroendocrine cells

� Typical arrangement of endocrine tissue:� in radially arranged cords or

in narrow anastomosing cordscords� adenohypophysis� parathyroid glands� adrenal glands

� epithelial vesicles – folliclesfollicles� thyroid gland

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Endocrine glandsEndocrine glands

44

�� Endocrine cellsEndocrine cells::� aggregated asas distinctdistinct endocrineendocrine glandsglands:

� pituitary gland� pineal gland� thyroid gland� parathyroid glands� adrenal glands

�� a distinct part of certain organsa distinct part of certain organs:� islets of Langerhans in the pancreas� collection of cells in:

o hypothalamuso testis (Leydig cells)o ovary – follicular and theca cells

�� single endocrine cellssingle endocrine cells – paracrine signaling

� intestinal enteroendocrine cells

� Typical arrangement of endocrine tissue:� in radially arranged cords or

in narrow anastomosing cordscords� adenohypophysis� parathyroid glands� adrenal glands

� epithelial vesicles – folliclesfollicles� thyroid gland

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Pituitary glandPituitary gland, , hypophysishypophysis

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�� Pituitary glandPituitary gland, , hypophysis cerebri hypophysis cerebri (Lat. glandula pituitaria)(Lat. glandula pituitaria)::

� small, unpaired body

� housed in the sella turcica

� overlapped by diaphragma sellae

� connected to the hypothalamus by a neural stalk, infundibulum

� External morphology:� ovoid shape

� weight ~0.5 g (>1 g multipara)

� size:

� length 8-10 mm

�width 12-15 mm

� height 5-6 mm

� color – reddish-grey

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Macroscopic anatomyMacroscopic anatomy

66

� Anatomical partsparts::� anterior pituitary,

adenohypophysisadenohypophysis (anterior lobe):(anterior lobe):� pars distalis – 75% of the mass� pars intermedia� pars tuberalis

� posterior pituitary, neurohypophysisneurohypophysis (posterior lobe):(posterior lobe):� lobus nervosus – 25% of the mass� infundibulum

o pedunculus infundibulariso eminentia mediana

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Microscopic anatomyMicroscopic anatomy

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�� AdenohypophysisAdenohypophysis –– cellcell typestypes::� chromophobes, endocrinocyti chromophobiendocrinocyti chromophobi::

� 50-60% of the cell population� small (12-15) agranular cells� stem cells

� chromophils, endocrinocyti chromophili:endocrinocyti chromophili:� acidophilic cells, endocrinocytiendocrinocyti acidophiliacidophili – 30-40%

� somatotropic cells – STH� mammotropic cells – prolactin (luteotropic hormone)

� basophilic cells, endocrinocytiendocrinocyti basophilibasophili – 4-10%� gonadotropic cells – FSH and LH� thyrotropic cells – TTH and TSH� corticotropic cells – ACTH and MSH (melanotropin)

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Microscopic anatomyMicroscopic anatomy

88

�� NeurohypophysisNeurohypophysis::� pituicytes, pituicytipituicyti::

� glial cells – 25% of its volume� highly branched processes

� neurosecretory axons � Herring bodies� axovasal synapses, synapses axovasculares� neurosecretory material:

o neurohypophyseal hormones• oxytocin• Arg-vasopressin (antidiuretic hormone, ADH)

o neurophysin – a binding glycoproteino АТP

� postganglionic sympathetic terminals –catecholamines

� axonal endings in synaptic contactwith neurosecretory terminals

�� Pars intermedia Pars intermedia – 2%:� weakly basophilic cells

– MSH (intermedin)� chromophobes

– Rathke’s cleft cysts

�� Pars tuberalis Pars tuberalis – 2%:� a funnel-shaped region � arranged in cell cords –

gonadotropins (FSH and LH)� small follicles

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Effects of hypophyseal hormonesEffects of hypophyseal hormones

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NB:NB: pituitary gland is the conductor of the endocrine orchestrapituitary gland is the conductor of the endocrine orchestra!!

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 1010

�� Hypothalamic nucleiHypothalamic nuclei::� nucleus supraopticus et paraventricularis

� tractus supraopticohypophysialis� tractus paraventriculohypophysialis

� axovasal synapses – neurohypophysis, Herring bodies

�� Hypothalamic nucleiHypothalamic nuclei::� nucleus ventromedialis� nucleus dorsomedialis� nucleus infundibularis

� neurosecretory cells –releasing- and inhibitory-hormones

� rete capillare primarium ofeminentia mediana

� hypophyseal portal system,vv. portae hypophysis

HHypothalamoypothalamo--hypophyseal hypophyseal portal systemportal system

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Pineal glandPineal gland, , epiphysis cerebriepiphysis cerebri

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�� Pineal glandPineal gland, , epiphysis cerebri epiphysis cerebri (Lat. glandula s. corpus pineale)(Lat. glandula s. corpus pineale)::� small, unpaired body

� part of the epithalamus

� occupies the depression between colliculi superiores

� connected with habenulae tocommissura habenularum

� recessus pinealis – third ventricle

� grows in size until 1-2 years of age; undergoes involution after age 7

� External morphology:� pine cone-shaped (piriform) body

� weight ~120 mg

� size:� length 5-8 mm

� width 3-5 mm

� height 5-6 mm

� color – reddish-grey organ

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Microscopic structureMicroscopic structure

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�� Pineal parenchymaPineal parenchyma –– cell typescell types::� pinealocytes, endocrinocytiendocrinocyti pinealespineales

� arranged in cords and follicles

� production of melatonin and pineal peptides – vasotocin

�� Pineal stromaPineal stroma:� neuroglial cells, gliocyti centrales gliocyti centrales – 5-10%

� astrocytes – supportive function

�microglial cells – phagocytic function

� calcified concretions or “brain sand”,acervuli cerebri (corpora aranacea)� up to 1 mm in diameter

� accrue with age � degenerative changes

� covered by pial connective tissue capsule

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Thyroid glandThyroid gland, , glandula thyroideaglandula thyroidea

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�� Thyroid glandThyroid gland, , glandula thyroideaglandula thyroidea::� the largest endocrine glands� anteriorly in the lower part of the neck

� External morphology:� a "butterfly" shape, thyroid (Gr. “shield”)� weight 20-40 g� size:

� transverse 3 cm� anterior-posterior 2 cm� height 5 cm

� color – brownish-red

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Macroscopic anatomyMacroscopic anatomy

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� Anatomical partsparts::� two large lobes – conical in shape:

�� right and left lobesright and left lobes

�� isthmus gl. thyroideaeisthmus gl. thyroideae

� length – 1-1.5 cm

�at ІІ-ІV tracheal cartilage

�pyramidal lobe,lobuslobus pyramidalispyramidalis

�variable in length

�occasionally absent

�remnant from ductus thyroglossus

�gll. thyroideae accessoriae

� thin fibrous capsule

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Microscopic anatomyMicroscopic anatomy

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�� Thyroid parenchymaThyroid parenchyma, , parenchymaparenchyma::� follicles, folliculi gl. thyroideae folliculi gl. thyroideae

� total number – 20-30 million� spherical or ovoid structures, d=35-500 µm� contain a gelatinous substance, colloid

� secretory product is stored in great quantity

� surrounded by an extensive lymphatic and fenestrated blood capillary network

� simple cuboidal secretory epithelium:oo follicular cellsfollicular cells, ,

thyrocytesthyrocytes• produce thyroid hormones,

triiodothyronine (T3) and triiodothyronine (T3) and thyroxine (T4)thyroxine (T4)

• stimulation from TTH• thyroid colloid, thyroglobulin

oo parafollicular cellsparafollicular cells, , clear or light, Cclear or light, C--cellscells

• secretion of calcitonincalcitonin• part of the

follicular epithelium • isolated clusters

between thyroid follicles

o basal lamina

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Synthesis and accumulation Synthesis and accumulation of of thyroid thyroid hormoneshormones

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ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Parathyroid glandsParathyroid glands, , glandulae parathyroideaeglandulae parathyroideae

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�� Parathyroid glandsParathyroid glands, , glandulae parathyroideae:glandulae parathyroideae:

�� gll. parathyroideaegll. parathyroideae superioressuperiores

�� gll. parathyroideaegll. parathyroideae inferioresinferiores� usually four small glands

� variable number and location

� located behind the thyroid gland, at each end of its upper and lower poles

� sometimes embedded in the thyroid gland

� contained within a connective tissue capsule

� External morphology:� ovoid or bean-like shape

� total weight 30-50 mg

� size:� length 6 mm� width 3-4 mm� thickness 2-3 mm

� 'mustard yellow' color

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Microscopic anatomyMicroscopic anatomy�� ParenchymaParenchyma – lobulated structure:

� anastomosing cords of parenchymal cells,

parathyrocytesparathyrocytes::

� chief (principal) cells, endocrinocytiendocrinocyti principalesprincipales

o small polygonal cells with granules

o contain parathyroid hormone

� oxyphil (eosinophil) cells,

endocrinocyti oxyphilicae (acidophilicae)endocrinocyti oxyphilicae (acidophilicae)

o appear just before puberty

o up to 3% of the cell population

o larger in size

o unknown function

� intermediate forms

between chief and oxyphil cells

� adipose cells – more than 50%

of the gland in older people

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ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Adrenal (suprarenal) gland, glandula suprarenalis (adrenalis)

� orange-colored paired organs

� location:� in the retroperitoneum

� on the superior poles of the kidney, embedded in adipose tissue

� shape:� right – triangular

� left – half-moon shape

� size:� length – 5-6 cm

� width – 3-4 cm

� thickness – 1 cm

� weight:� right – 4-5 g

� left – 5-7 g

� size and mass – age-relatedand functionally variable

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ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Macroscopic anatomyMacroscopic anatomy� Two margins and three surfaces:

� margo superior et medialis� facies renalis – basis� facies anterior – hilum� facies posterior

� Anatomical partsparts:� adrenal cortexcortex – a yellow

peripheral layer – 99/10/10

� adrenal medullamedulla – a reddish-browncentral layer – 1/101/10

� capsule – two layers� subcapsular layer of

epithelial cells �accessory glands, gll. suprarenales accessoriae:� spermatic cord� epididymis� lig. latum uteri

2020

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Microscopic structureMicroscopic structure

�� Adrenal cortexAdrenal cortex –– endocrynocytus corticalisendocrynocytus corticalis– steroid hormones:� zona glomerulosa (15%) – mineralocorticoids� zona fasciculata (60%) – glucocorticoids (cortisol)

� pars externa et interna

� zona reticularis (35%) –androgens and (possibly) glucocorticoids?

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ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

�� Adrenal medullaAdrenal medulla –– cellulae chromaffinae cellulae chromaffinae (medullary cells):� endocrinocyti lucidi � epinephrine

(adrenaline – 80%)� endocrinocyti densi � norepinephrine -

(noradrenaline – 20%)

��

pheochromocytomapheochromocytoma

Microscopic structureMicroscopic structure

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ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

� Embryonic origin – neuroectodermneuroectoderm(neural crest)

� chromaffin cells, chromaffinocyti (type І)� epitheloid satellite cells (type ІІ)

� aortic bodies, paragangliparagangliаа aortica aortica (of Zuckerkandl) – 1 cm

� carotid body, glomus caroticumglomus caroticum� jugular body, glomusglomus jugularejugulare – 0.5 mm

� coccygeal body, glomus coccygeum glomus coccygeum (Luschka’s gland) – 2-3 mm

ParagangliaParaganglia

Emil Zuckerkandl Emil Zuckerkandl (1849(1849--1910)1910)

Hubert Luschka Hubert Luschka (1820(1820--1875)1875)

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ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Endocrine testisEndocrine testis�� Interstitial cellsInterstitial cells ((ofof LeydigLeydig), ),

endocrinocyti interstitialeendocrinocyti interstitialess –12% of the testicular volume

� Embryonic originorigin:� mesenchymal?� neuroectodermal?

� fenestrated capillaries� steroid-secreting cells – testosterone� hormonal control – luteinizing hormone

(LH or ICSH) from the hypophysis

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ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Endocrine ovaryEndocrine ovary�� endocrinocyti thecalesendocrinocyti thecales, , thecatheca cellscells

– theca interna

�� epitheliocyti follicularesepitheliocyti folliculares, , follicular or follicular or granulosa cellsgranulosa cells – stratum granulosum

� fenestrated capillaries� synthesize estrogens (estradiol)

and gestagens (progesterone)� hormonal control – follicle-stimulating

hormone (FSH) and luteinizing hormone (LH) from the hypophysis

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ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Endocrine pancreasEndocrine pancreas, , pars endocrina pancreatispars endocrina pancreatis

�� Islets of LangerhansIslets of Langerhans, , insulae pancreaticae Langerhansiinsulae pancreaticae Langerhansi

�� numbernumber: > 1 million (1-2%)� total weightweight: ~ 1 g

�� locationlocation:: more abundant in the tail, cauda pancreatis

�� sizesize: : diameter 100-300 µm

�� fine capsule of reticular fibersfine capsule of reticular fibers

�� a network of blood capillariesa network of blood capillaries, , rete capillare

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ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Islets ofIslets of LangerhansLangerhans�� three principal cell typesthree principal cell types, , inculocytiinculocyti:

�� АА ((αα))--cellscells – 15-20% � glucagonglucagon

�� BB ((ββ))--cellscells – 60-80% � insulininsulin

�� D D ((δδ))--cellscells (A1-cells) – 5-10% �somatostatinsomatostatin

� other cell types – 5%:�� PPPP ((FF))--cellscells – 2-5% �

pancreatic polypeptidepancreatic polypeptide

�� DD11--cellscells – 0.5-1% �vasoactive intestinal polypeptidevasoactive intestinal polypeptide

�� ECEC--cellscells – isolated �

secretinsecretin, , motilinmotilin, , substancesubstance P, P, serotoninserotonin, , dopaminedopamine

�� GG--cellscells � gastringastrin

�� YY--cellscells � ghrelinghrelin

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ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Gastroenteropancreatic Gastroenteropancreatic ((GEP)GEP)endocrine systemendocrine system

� GEP = all the enteroendocrine (chromaffin) cellsof the digestive system

� APUD = Amine Precursor Uptake and Decarboxylation

� DNES = diffuse neuroendocrine system or

paraneuronparaneuron conceptAGE PearseAGE Pearse(1916(1916--2003)2003) 2828

ENDOCRINOLOGY

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov

Thank youThank youThank youThank you ............

So, at long last, So, at long last, here are the glandshere are the glands!!

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