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Endocrine Organs

Endocrine Organs. Intercellular communication : nervous system : neurotransmitters endocrine system : hormones : Hormone : steroids : small peptides, proteins, glycoproteins : amino acid analogues and derivatives :. Hypophysis. Adenohypophysis : pars distalis : pars intermedia :

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Endocrine Organs

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  1. Endocrine Organs • Intercellular communication : • nervous system : neurotransmitters • endocrine system : hormones : • Hormone : • steroids : • small peptides, proteins, glycoproteins : • amino acid analogues and derivatives :

  2. Hypophysis • Adenohypophysis : • pars distalis : • pars intermedia : • pars tuberalis : • Neurohypophysis : • pars nervosa : • infundibulum :

  3. Blood Supply • Blood supply : • superior hypophyseal arteries : • pars tuberalis, median eminence, infundibular stem • inferior hypophyseal arteries : • pars nervosa • hypophyseal portal System : anterior lobe • primary capillary plexus • secondary capillary plexus :

  4. Adenohypophysis • Tropic homones : • regulate activity in other endocrine glands • Stain reaction : • basophils : 10% • acidophils : 40% • chromophobes : 50% • Hormones : • small proteins or glycoproteins

  5. Hormones • Andenocorticolipotropes : • adrenocorticotropic hormone (ACTH), lipotropic hormone (LPH) • Gonadotropes : • luteinizing hormone (LH), follicle-stimulating hormone (FSH) • Thyrotropes : thyroid-stimulating hormone (TSH) • Somatotropes : somatotropin • Lactotropes : prolactin (PR) or lactogenic hormone (LTH)

  6. Neurohypophysis • Neurosecretory neuron : • supraoptic nuclei : • parventricular nuclei : • Storage site of neurosecretion : • secretory granules Herring bodies • Hormones : • vasopressin (antidiuretic hormone) (ADH) • oxytocin • neurophysin : hormone-binding protein

  7. Hormone and Pituicyte • ADH : • secretory neucrons : serve as osmoreceptors • increase permeability of distal portion of nephron • disease : diabetes insipidus • Oxytocin : • smooth muscle contraction : • uterine : copulation and parturition • myoepithelial cells : breast • Pituicyte : astrocyte

  8. Hypothalamus and Pineal Gland • Hypothalamus : • regulate function : • promote or inhibit secretion of adenohypophysis hormone • ADH and oxytocin production • Pineal gland : • melatonin : inhibiting steroidogenic activity of gonads • cell : • pinealocytes, interstitial (glial) cell • corpora arenacea (brain sand)

  9. Thyroid Gland • Follicle : • follicular (principal) cell : secrete T3,T4 • secretory and absorptive cell : colloidal resorptive droplets • thyroid hormone : stimulate metabolism • colloid : gel-like mass • thyroglobulin (inactive storage form) • parafollicular cell : secrete calcitonin • calcitonin : descrease blood calcium level by suppress bone resorption and increase osteoid calcification

  10. Parathyroid Glands • Embryology : third branchial pouch • Cell consist : • principal (chief) cells : secrete PTH • oxyphils cell : • Parathyroid hormone (PTH) : • function : increase blood calcium level : • stimulate bone resorption : • reduce kidney excretion of calcium : • increase intestinal absorption of calium :

  11. Adrenal Glands • Regional organization • Cortex : steroid-secreting portion • medulla : catecholamine-secreting portion • Blood supply : • capsular capillaries : • fenestrated cortical sinusoidal capillaries : • medullary arterioles :

  12. Zonation of Adrenal Cortex • Zona glomerulosa : • mineralocorticoids : aldosterone (renin-angiotensin system) • Zona fasciculata : • glucocorticoids : hydrocortisone (cortisol) • gluconeogenesis and glycogenesis • feedback control : hypothalamic-hypophyseal CRF-ACTH system • Zona Reticularis : • weak androgens : dehydroepiandrosterone (DHA) • glucocorticoids : hydrocortisone (cortisol)

  13. Adrenal Medulla • Chromaffin cell : modified neurons • norepinephrine population : large dense core granule • epinephrine population : small, less dense granule • glucocorticoid induce the conversion norepinephrine to epinephrine in medullary cells • catecholamine : fight-flight response • stimulate glycogenolysis • mobilization of free fatty acids from adipose tissues • rise blood pressure, cardiac output, increase breathing

  14. Fetal Adrenal Gland • Outer permanent cortex : • thin • Inner fetal zone : • thick • disappearance after birth • Lack a definitive medulla : • Under CRF-ACTH feedback system : • Part of fetal-placental unit :

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