ENDOCRINE SYSTEM ENDOCRINE GLANDS

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ENDOCRINE  SYSTEM(ENDOCRINE GLANDS)
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• nervous system
• electrochemical signals
• endocrine system
• chemical agents hormone
• characteristics of the endocrine gland
• ductless
• well vascularized
• hormone secretion

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• endocrine gland hypophysis, thyroid gland,
  parathyroid gland, adrenal gland, pineal body,
  pancreas, testis, ovary, liver

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I.  HYPOPHYSIS

• 1 x 1.5 x 0.5 cm,  0.5 gr
• master gland located in sella trucica

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• oral ectodermal origin adenohypophysis
• pars distalis, pars tuberalis, pars intermedia
• neural ectodermal origin neurohypophysis
• pars infundibularis,  pars nervosa
• anterior and posterior lobe
• anterior lobe pars distalis, pars tuberalis
• posterior lobe pars nervosa, pars intermedia

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• 1. Adenohypophysis
• 1) Pars distalis
• 75 of total hypophysis
• Chromophils(50) 12-15µm
• acidophils(a-cell 35) basophils(ß-cell)
• Chromophobe(50)
• smaller than chromophils

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• A. Acidophils
• somatotroph growth hormone
• mammotroph(lactotroph) prolactin
• B. Basophils               
• gonadotroph follicular stimulating hormone(FSH)
• luteinizing hormone(LH) or
• interstitial cell stimulating hormone(ICSH)
• thyrotroph thyroid stimulating hormone(TSH)
• corticotroph adrenocorticotrophic hormone(ACTH)
• C. Chromophobes  
• stem cell
• inactivated chromophils

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• 2) Pars intermedia    
• 3 of the human fetal hypophysis
• degeneration in adults
• well developed in some animals
• especially in amphibians MSH secretion
• 3) Pars tuberalis
• Chromophobes, chromophils(gonadotropins)

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• 2. Neurohypophysis  
• axon and axon terminal from hypothalamus
  hypothalamo-hypophyseal tract
• neuronal cell body in nucleus of the
  hypothalamus
• suprachiasmatic and paraventricular nucleus
• release oxytocine, vasopressin
• dorsal medial N, ventral medial N, and
  infundibular N
• release neuropeptide  to the adenohypophysis
• via the portal system
• neuroglial cells(pituicyte)

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• 3. Blood vessels
• internal carotid a ? superior and inferior
  hypophyseal artery
• superior hypophyseal a.
• ? pars infundibularis
• ? primary capillary plexus
• ? hypophyseal portal vein
• ? adenohypophysis
• ? secondary capillary plexus
• ? vein ? cavernosus sinus
• inferior hypophyseal a.
• ? pars nervosa
• ? capillary plexus
• ? vein ? cavernosus sinus

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4. Hypophysis and hypothalamus hypophyseal
portal system and hypothalamohypophyseal tract
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II. Adrenal gland(Suprarenal gland)

• paired organs
• located in superior pole of each kidney
• triangle or semilunar shape
• 8-20g, 4-6cm length,
• 1-2cm width, 0.5cm thickness
• capsule
• cortex mesordermal origin(80-90)
• medulla neural crest orgin(10-20)

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• 1. Adrenal cortex     
• 3 layers glomerulosa, fasciculata, reticularis
• (1) Zona glomerulosa   
• 15 of cortex
• columnar or pyramidal cells round or ellipsoisal
  arrangement
• mineralocorticoids aldosterone
• (2) Zona fasciculata
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• 78 of cortical volume
• polyheadral cells longitudinal column
• glucocorticoids cortisol, corticosterone
• small amount of androgen and estrogen
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• (3) Zona reticularis

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2. Adrenal medulla    large epitheloid cells in
cluster or cell cords chromaffin
cells norepinephrine, epinephrine nerve cell
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• 3. Blood supply of the adrenal gland
• superior(from inferior phrenic artery),
  middle(from aorta) and inferior(from renal
  artery) suprarenal artery
• ? subcapsular arterial plexus(SAP)

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i, SAP ? short cortical artery(cortical atery) ?
sinusoid(in cortex) ? venule(in medulla) ?
suprarenal vein ii, SAP ? long cortical
artery(medullary artery) ?capillary network(in
medulla) ? venule ? suprarenal vein
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• 4. Histophysiology of the adrenal cortex
• (1) Hyperadrenocorticism
• Cushings syndrome
• excessive secretion of ACTH
• excessive secretion of glucocorticoids
  obesity(face, neck, trunk), hirsutisim,
  impotence, amenorrhea
• Conn's syndrome
• excessive secretion of aldosterone
• (2) Hypoadrenocorticism(Addison's disease)
• destruction of adrenal cortex
• weakness, weight loss, low blood pressure,
  increase skin pigmentation

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III. Thyroid gland  

• 1. Anatomical Structure
• 25-40g
• thyroid cartilage
• 6th tracheal cartilage
• two lateral lobe
• isthmus
• pyramidal lobe

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2. Blood Supply
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• 3. Histological organization
• colloid follicle
• follicular(principal) cell
• thyroxin
• parafollicular cell
• calcitonin

Fig. 15-43. Thyroid gland. H-E stain
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• 4. Histophysiology of the thyroid gland
• (1) Thyroid hormone
• increase the basal metabolic rate
• absorption of carbohydrates
• protein synthesis development, differentiation,
  growth
• a. hypothyroidism   
• lowering metabolic rate
• in child
• Cretinism mental retardation, dwarfing
• in adults myxedema
• b. hyperthyroidism(thyrotoxicosis)   
• Grave's disease or exopthalmic goiter
• c. thyroid stimulating hormone
• (2) Calcitonin

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IV. Parathyroid gland   

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• 4-6 glands
• located on posterior surface of the thyroid
  gland
• 5mm in length, 4mm in width, 2mm in thickness
• 25-50mg

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cell groups chief cell parathyroid
hormone oxyphil cell unknown function
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• Histophysiology of the parathyroid gland   
• parathyroid hormone(PTH)
• increase blood calcium level
• Hyperparathyroidism   
• decrease blood phosphate level, increase blood
  calcium level
• pathological deposition of Ca soft tissue
  calcification, bone fracture
• Hypoparathyroidism   
• decrease blood calcium level, increase blood
  phosphate level
• over excitability of nervous system, tetany

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V. Pineal body pineal gland, epiphysis cerebri

• posterior end of roof of the 3rd ventricle
• 5-8mm in length, 3-5mm in width
• 0.1-0.2 g
• Cells
• pinealocyte melatonin secretion
• interstitial cell astrocyte like cell

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• Corpora arenacea(brain sand)
• calcium phosphate, carbonate
• land mark for X-ray, CT

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• Histophysiology of the pineal gland(continue)
• seaonal changes in melatonin and testes
• Syrian hamster
• in summer 3,000 mg weight of testes
• in winter 300 mg
• pineal gland, melatonin and adolescence
• pineal peptides arginin vasotocin,
  angigonadotrophin, gonadotrophin releasing factor
• neuroepiphysins
• Descartes "seat of the rational soul
• seasonal mood disorsers, jet lag