endocrine system components endocrine glands: thyroid gland,parathyroid endocrine glands: thyroid...
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Endocrine systemEndocrine system
ComponentsComponents endocrine glands: thyroid gland,parathyroid endocrine glands: thyroid gland,parathyroid gland,adrenal gland,pituitary gland,adrenal gland,pituitary gland,pineal body,etc. gland,pineal body,etc. Scattered endocrine cells: islet cells of Scattered endocrine cells: islet cells of pancreas,etc.pancreas,etc.Function: Function: secreting hormonessecreting hormones which regulate the which regulate the functions of the body and functions of the body and maintenance of maintenance of a steady internal environment state. a steady internal environment state.
general characteristics general characteristics of the endocrine systemof the endocrine system
1.Glandular cells arranged in cords,clumps, 1.Glandular cells arranged in cords,clumps, networks or follicles;networks or follicles;
2. Without ducts2. Without ducts ;;
3. Abundant in capillaries3. Abundant in capillaries 。。
thyroid glandthyroid gland
thyroid follicles full of homogeneous materials called colloid
1. principal cell1. principal cell
(( 11 )) LM: its shape varies with functional stateLM: its shape varies with functional state
(( 22 )) EM: numerous microvilli on free surface;EM: numerous microvilli on free surface; Golgi complexGolgi complex ,, mitochondria in mitochondria in cytoplasm;cytoplasm; secreting granules and colloid vesiclessecreting granules and colloid vesicles in the top of cytoplasm.in the top of cytoplasm.(( 33 )) function: synthesize and secret function: synthesize and secret thyroid thyroid hormone.hormone.
Synthesis of thyroid hormoneSynthesis of thyroid hormone
I+ absorbed from bloodby follicular cells
Glycoprotein synthesized by follicular cells
Thyroid hormones ( T3 and T4)
Monoiodotyrosyls or diiodotyrosyls
Taken back into the follicular cells to further modification
Iodinated thyroglobulin (colloid in the follicles)
3. Function of T3. Function of T33 and T and T44
Stimulates metabolism;Stimulates metabolism;
Increase nerve excitability;Increase nerve excitability;
Promote the growth and development.Promote the growth and development.
Hypothyroidism during development----cretinis
m
in the adult----myxedema
Hyperthyroidism--eyes that seem to be popping out of
their sockets, trembling hands,etc.
Myxedema and hyperthyroidism
cretinscretins
parafollicular cell (C cell)parafollicular cell (C cell)
1.distribution:1.distribution: between follicles or between follicles or between follicular cells.between follicular cells.
2. profile2. profile :: larger and stain more lightly.larger and stain more lightly.
3.function:3.function: secreting hormone secreting hormone calcitonincalcitonin which which decreasesdecreases the [Ca2+] in the blood. the [Ca2+] in the blood.
C cellsC cells
C cells
parathyroid glandparathyroid gland
1.Chief cell (principal cell): 1.Chief cell (principal cell): secreting secreting parathormoneparathormone
which tends to which tends to increaseincrease the l the level of serum calciumevel of serum calcium
2. Oxyphil (eosinophil cell)2. Oxyphil (eosinophil cell) ::the function is unclear.the function is unclear.
parathyroid glandparathyroid gland
adrenal glandadrenal gland
Adrenal gland
cortex
medulla
Zona glomerulosa
Zona fasciculasa
Zona reticularis
1. Zona glomerulosa (ZG)1. Zona glomerulosa (ZG)
Cells arranged in groups
Cells: smaller , cuboidal
or low columnar, stained densely.
Producing mineralocorticoid hormones to influence the electrolyte and water balance
zona glomerulosa zona glomerulosa
2. zona fasciculasa (ZF)2. zona fasciculasa (ZF)
Cells arranged in cords ;
Cells:larger,polyhedral, stained lightly
Producing glucocorticoids cortisone and cortisol. Also producing DHA(an androgen).
zona fasciculasa zona fasciculasa
3. zona reticularis (ZR)3. zona reticularis (ZR)
Cell cords form networks
Cells: smaller , cuboidal or low columnar, stained densely.
Producing some glucocorticoid and sex hormones: androgens and estrogens.
zona reticulariszona reticularis
Medulla of adrenal glandMedulla of adrenal gland
Chromaffin cellsAdrenaline cells secret adrenalin
Nordrenaline cells secret noradrenalin
Adrenal gland
cortex
Medulla—adrenaline and noradrenaline
ZG--mineralocorticoid hormones
ZF—glucocorticoid hormones and androgen.
ZR-- glucocorticoid and sex hormones
(androgen and estrogen)
pituitary gland (hypophyspituitary gland (hypophysis cerebri)is cerebri)
Subdivision of the pituitary Subdivision of the pituitary
NeurohypophysisNeurohypophysis pars posterior (pars nervosa)pars posterior (pars nervosa) infundibuluminfundibulum
AdenohypophysisAdenohypophysis pars anterior (pars distalis) pars anterior (pars distalis) pars tuberalispars tuberalis pars intermediapars intermedia
adenahypophysisadenahypophysis
1.Pars anterior: several types of cells are responsible for
production hormones .It is rich in
fenestrated capillaries.
Pars anteriorPars anterior
Chromophil cells
acidophil
somatotropic cell (somatotroph) — somatotropin(STH) or growth hormone(GH)
mammotroph — prolactin(PRL)
basophil
Corticotroph — adreno-corticotropin(ACTH)
Thyrotroph — thyrotropin(TSH)
Gadotroph — follicle stimulating hormone(FSH) and
luteinizing hormone(LH) in female;
interstitial cell stimulating hormone(ICSH) in male
Chromophobe cells
Pars anteriorPars anterior
Pars anteriorPars anterior
2. Pars tuberalis2. Pars tuberalis
Mainly consisting of undifferentiated cells.
Some acidophil and basophil cells are also present.
3. Pars intermedia3. Pars intermediaPoorly developed in human hypophysis
Some cells can produce melanocyte stimulating hormone(MSH),
Other cells can produce ACTH.
Pars intermediaPars intermedia
4. 4. Blood supply of hypophysisBlood supply of hypophysis
Superior hypophyseal artery
Capillary plexuses in median eminence and infundibular stalk
Portal vessels in infundibulum
Sinusoids in pars anterior
Veins ending in venous sinuses
Hypothalamo
-hypophyseal
portal system
Hypothalamus secrets releasing hormones
Capillary plexuses in median eminence and infundibular stalk
Portal vessels in infundibulum
Hypothalamo
-hypophyseal
portal system
5. The relationship between 5. The relationship between hypothalamus and pars anteriorhypothalamus and pars anterior
Nerve impulse
Sinusoids in pars anterior
target gland
Pars posteriorPars posteriorIt mainly composed of unmyelinated axons of the neurons in hypoth
alamus and pituicytes.
Pars posterior and hypothalamus are structural and functional unity.
Supraoptic nucleus:
producing antididuretic
hormone (ADH)
Paraventricular nucleus:
producing oxytocin
Pars posteriorPars posterior
hypophysishypophysis
Key pointsKey points
1. Structure of thyroid gland and the function of two ty1. Structure of thyroid gland and the function of two type of cells in thyroid gland.pe of cells in thyroid gland.
2. The function of chief cell in parathyroid gland.2. The function of chief cell in parathyroid gland.
3. Structure of adrenal gland( cortex and medulla)3. Structure of adrenal gland( cortex and medulla) ,, tthe secretions of medulla and 3 zona of cortex .he secretions of medulla and 3 zona of cortex .
4. The structure of pituitary;cell types in pars anterior 4. The structure of pituitary;cell types in pars anterior and their secretions;the relationship between hypotand their secretions;the relationship between hypothalamus and pituitary (pars anterior and pars posterhalamus and pituitary (pars anterior and pars posterior); ior); Hypothalamo-hypophyseal portal system