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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

22

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

55

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

77

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 P

postganglionic sympathetic terminals catecholamines

axonal endings in synaptic contactwith neurosecretory terminals

Pars intermedia Pars intermedia 2%: weakly basophilic cells

MSH (intermedin) chromophobes

Rathkes 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

99

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

1111

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

1212

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

1313

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

1414

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 -V 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

1515

Thyroid parenchymaThyroid parenchyma, , parenchymaparenchyma:: follicles, foll