Endocrine Mechanisms

Endocrine glands in the human head and neck and their hormones

Secreted hormone Abbreviation Produced by Effect
Thyrotropin-releasing hormone TRH Parvocellular neurosecretory neurons Stimulate thyroid-stimulating hormone (TSH) release from anterior pituitary(primarily)
Dopamine
(Prolactin-inhibiting hormone)
DA or PIH Dopamine neurons of the arcuate nucleus Inhibit prolactin released from anterior pituitary
Growth hormone-releasing hormone GHRH Neuroendocrine neurons of the Arcuate nucleus Stimulate Growth hormone (GH) release from anterior pituitary
Somatostatin
(growth hormone-inhibiting hormone)
SS, GHIH, or SRIF Neuroendocrine cells of the Periventricular nucleus Inhibit Growth hormone release from anterior pituitary
Inhibit thyroid-stimulating hormone (TSH) release from anterior pituitary
Gonadotropin-releasing hormone GnRH or LHRH Neuroendocrine cells of the Preoptic area Stimulate follicle-stimulating hormone (FSH) release from anterior pituitary
Stimulate luteinizing hormone (LH) release from anterior pituitary
Corticotropin-releasing hormone CRH or CRF Parvocellular neurosecretory neurons of the Paraventricular nucleus Stimulate adrenocorticotropic hormone (ACTH) release from anterior pituitary
Vasopressin
(antidiuretic hormone)
ADH or AVP or VP Parvocellular neurosecretory neurons, Magnocellular neurosecretory neurons of the Paraventricular nucleus and Supraoptic nucleus Increases water permeability in the distal convoluted tubule and collecting duct of nephrons, thus promoting water reabsorption and increasing blood volume

Secreted hormone From cells Effect
Melatonin Pinealocytes Antioxidant
Monitors the circadian rhythm including induction of drowsiness and lowering of the core body temperature

The pituitary gland (or hypophysis) is an endocrine gland about the size of a pea and weighing 0.5 grams (0.018 oz) in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity (sella turcica) covered by a dural fold (diaphragma sellae). The pituitary is functionally connected to the hypothalamus by the median eminence via a small tube called the infundibular stem or pituitary stalk.[1] The anterior pituitary (adenohypophysis) is connected to the hypothalamus via the hypothalamo–hypophyseal portal vessels, which allows for quicker and more efficient communication between the hypothalamus and the pituitary.[2]

Secreted hormone Abbreviation From cells Effect
Growth hormone
(somatotropin)
GH Somatotrophs Stimulates growth and cell reproduction
Stimulates Insulin-like growth factor 1 release from liver
Thyroid-stimulating hormone
(thyrotropin)
TSH Thyrotrophs Stimulates thyroxine (T4) and triiodothyronine (T3) synthesis and release from thyroid gland
Stimulates iodine absorption by thyroid gland
Adrenocorticotropic hormone
(corticotropin)
ACTH Corticotrophs Stimulates corticosteroid (glucocorticoid and mineralcorticoid) and androgensynthesis and release from adrenocortical cells
Beta-endorphin Corticotrophs Inhibits perception of pain
Follicle-stimulating hormone FSH Gonadotrophs In females: Stimulates maturation of ovarian follicles in ovary
In males: Stimulates maturation of seminiferous tubules
In males: Stimulates spermatogenesis
In males: Stimulates production of androgen-binding protein from Sertoli cells of the testes
Luteinizing hormone LH Gonadotrophs In females: Stimulates ovulation
In females: Stimulates formation of corpus luteum
In males: Stimulates testosterone synthesis from Leydig cells (interstitial cells)
Prolactin PRL Lactotrophs Stimulates milk synthesis and release from mammary glands
Mediates sexual gratification
Melanocyte-stimulating hormone MSH Melanotropes in the Pars intermedia of the Anterior Pituitary Stimulates melanin synthesis and release from skin/hair melanocytes

Stored hormone Abbreviation From cells Effect
Oxytocin OX or OXT Magnocellular neurosecretory cells In females: uterine contraction during birthing, lactation (letdown reflex) when nursing
Vasopressin
(antidiuretic hormone)
ADH or AVP Parvocellular neurosecretory neurons Increases water permeability in the distal convoluted tubule and collecting duct of nephrons, thus promoting water reabsorption and increasing blood volume

Oxytocin and anti-diuretic hormone are not secreted in the posterior lobe, merely stored.

Secreted hormone Abbreviation From cells Effect
Triiodothyronine T3 Thyroid epithelial cell (More potent form of thyroid hormone)
Stimulates body oxygen and energy consumption, thereby increasing the basal metabolic rate
Stimulates RNA polymerase I and II, thereby promoting protein synthesis
Thyroxine
(tetraiodothyronine)
T4 Thyroid epithelial cells (Less active form of thyroid hormone)
(Acts as a prohormone to triiodothyronine)
Stimulates body oxygen and energy consumption, thereby increasing the basal metabolic rate
Stimulates RNA polymerase I and II, thereby promoting protein synthesis
Calcitonin Parafollicular cells Stimulates osteoblasts and thus bone construction
Inhibits Ca2+ release from bone, thereby reducing blood Ca2+

Endocrine Alimentary system en.svg

Secreted hormone Abbreviation From cells Effect
Gastrin (Primarily) G cells Secretion of gastric acid by parietal cells
Ghrelin P/D1 cells Stimulate appetite.
Neuropeptide Y NPY Increased food intake and decreased physical activity. It can be associated with obesity.
Somatostatin D cells Suppress release of gastrin, cholecystokinin (CCK), secretin, motilin, vasoactive intestinal peptide (VIP), gastric inhibitory polypeptide (GIP), enteroglucagonLowers rate of gastric emptying

Reduces smooth muscle contractions and blood flow within the intestine.[3]

Histamine ECL cells stimulate gastric acid secretion
Endothelin X cells Smooth muscle contraction of stomach[4]

Secreted hormone From cells Effect
Secretin S cells Secretion of bicarbonate from liver, pancreas and duodenal Brunner’s glandsEnhances effects of cholecystokinin, stops production of gastric juice
Cholecystokinin I cells Release of digestive enzymes from pancreasRelease of bile from gallbladder, hunger suppressant

Secreted hormone Abbreviation From cells Effect
Insulin-like growth factor (or somatomedin) (Primarily) IGF Hepatocytes insulin-like effectsregulate cell growth and development
Angiotensinogen and angiotensin Hepatocytes vasoconstrictionrelease of aldosterone from adrenal cortex dipsogen.
Thrombopoietin THPO Hepatocytes stimulates megakaryocytes to produce platelets[5]
Hepcidin Hepatocytes inhibits intestinal iron absorption and iron release by macrophages

The pancreas is a mixocrine gland and it secretes both enzymes and hormones.

Secreted hormone From cells Effect
Insulin (Primarily) β Islet cells Intake of glucose, glycogenesis and glycolysis in liver and muscle from blood.Intake of lipids and synthesis of triglycerides in adipocytes. Other anabolic effects
Glucagon (Also Primarily) α Islet cells Glycogenolysis and gluconeogenesis in liver.Increases blood glucose level.
Somatostatin δ Islet cells Inhibit release of insulin[6]Inhibit release of glucagon[6] Suppress the exocrine secretory action of pancreas.
Pancreatic polypeptide PP cells Self regulate the pancreas secretion activities and effect the hepatic glycogen levels.

Secreted hormone From cells Effect
Renin (Primarily) Juxtaglomerular cells Activates the renin–angiotensin system by producing angiotensin I of angiotensinogen
Erythropoietin (EPO) Extraglomerular mesangial cells Stimulate erythrocyte production
Calcitriol (1,25-dihydroxyvitamin D3) Proximal tubule cells Active form of vitamin D3Increase absorption of calcium and phosphate from gastrointestinal tract and kidneys inhibit release of PTH
Thrombopoietin stimulates megakaryocytes to produce platelets[5]

Secreted hormone From cells Effect
Glucocorticoids (chiefly cortisol) zona fasciculata and zona reticulariscells Stimulates gluconeogenesis
Stimulates fat breakdown in adipose tissue
Inhibits protein synthesis
Inhibits glucose uptake in muscle and adipose tissue
Inhibits immunological responses (immunosuppressive)
Inhibits inflammatory responses (anti-inflammatory)
Mineralocorticoids (chiefly aldosterone) Zona glomerulosa cells Stimulates active sodium reabsorption in kidneys
Stimulates passive water reabsorption in kidneys, thus increasing blood volumeand blood pressure
Stimulates potassium and H+ secretion into nephron of kidney and subsequent excretion
Androgens (including DHEA and testosterone) Zona fasciculata and Zona reticulariscells In males: Relatively small effect compared to androgens from testes
In females: masculinizing effects

Secreted hormone From cells Effect
Adrenaline (epinephrine) (Primarily) Chromaffin cells Fight-or-flight response:

  • Boost the supply of oxygen and glucose to the brain and muscles (by increasing heart rate and stroke volume, vasodilation, increasing catalysis of glycogen in liver, breakdown of lipids in fat cells)
  • Dilate the pupils
  • Suppress non-emergency bodily processes (e.g., digestion)
Noradrenaline (norepinephrine) Chromaffin cells Fight-or-flight response:

  • Boost the supply of oxygen and glucose to the brain and muscles (by increasing heart rate and stroke volume, vasoconstriction and increased blood pressure, breakdown of lipids in fat cells)
  • Increase skeletal muscle readiness.
Dopamine Chromaffin cells Increase heart rate and blood pressure
Enkephalin Chromaffin cells Regulate pain

Endocrine reproductive system en.svg

Secreted hormone From cells Effect
Androgens (chiefly testosterone) Leydig cells Anabolic: growth of muscle mass and strength, increased bone density, growth and strength,Virilizing: maturation of sex organs, formation of scrotum, deepening of voice, growth of beard and axillary hair.
Estradiol Sertoli cells Prevent apoptosis of germ cells[7]
Inhibin Sertoli cells Inhibit production of FSH

Secreted hormone From cells Effect
Progesterone Granulosa cells, theca cells Support pregnancy:[8]

  • Convert endometrium to secretory stage
  • Make cervical mucus thick and impenetrable to sperm.
  • Inhibit immune response, e.g., towards the human embryo
  • Decrease uterine smooth muscle contractility[8]
  • Inhibit lactation
  • Inhibit onset of labor.

Other:

  • Raise epidermal growth factor-1 levels
  • Increase core temperature during ovulation[9]
  • Reduce spasm and relax smooth muscle (widen bronchi and regulate mucus)

Anti-inflammatory

  • Reduce gall-bladder activity[10]
  • Normalize blood clotting and vascular tone, zinc and copper levels, cell oxygenlevels, and use of fat stores for energy
  • Assist in thyroid function and bone growth by osteoblasts
  • Increase resilience in bone, teeth, gums, joint, tendon, ligament, and skin
  • Promote healing by regulating collagen
  • Provide nerve function and healing by regulating myelin
  • Prevent endometrial cancer by regulating effects of estrogen
Androstenedione Theca cells Substrate for estrogen
Estrogens (mainly estradiol) Granulosa cells Structural:

  • Promote formation of female secondary sex characteristics
  • Accelerate height growth
  • Accelerate metabolism (burn fat)
  • Reduce muscle mass
  • Stimulate endometrial growth
  • Increase uterine growth
  • Maintain blood vessels and skin
  • Reduce bone resorption, increase bone formation

Protein synthesis:

  • Increase hepatic production of binding proteins

Coagulation:

  • Increase circulating level of factors 2, 7, 9, 10, antithrombin III, plasminogen
  • Increase platelet adhesiveness
  • Increase HDL, triglyceride, height growth
  • Decrease LDL, fat deposition

Fluid balance:

  • Regulate salt (sodium) and water retention
  • Increase growth hormone
  • Increase cortisol, SHBG

Gastrointestinal tract:

  • Reduce bowel motility
  • Increase cholesterol in bile

Melanin:

  • Increase pheomelanin, reduce eumelanin

Cancer:

  • Support hormone-sensitive breast cancers[11] (Suppression of production in the body of estrogen is a treatment for these cancers.)

Lung function:

  • Promote lung function by supporting alveoli.[12]
Inhibin Granulosa cells Inhibit production of FSH from anterior pituitary

Secreted hormone Abbreviation From cells Effect
Progesterone (Primarily) Support pregnancy:[8]

  • Inhibit immune response, towards the fetus.
  • Decrease uterine smooth muscle contractility[8]
  • Inhibit lactation
  • Inhibit onset of labor.
  • Support fetal production of adrenal mineralo- and glucosteroids.

Other effects on mother similar to ovarian follicle-progesterone

Estrogens (mainly Estriol) (Also Primarily) Effects on mother similar to ovarian follicle estrogen
Human chorionic gonadotropin HCG Syncytiotrophoblast Promote maintenance of corpus luteum during beginning of pregnancyInhibit immune response, towards the human embryo.
Human placental lactogen HPL Syncytiotrophoblast Increase production of insulin and IGF-1Increase insulin resistance and carbohydrate intolerance
Inhibin Fetal Trophoblasts Suppress FSH

Secreted hormone Abbreviation From cells Effect
Prolactin PRL Decidual cells milk production in mammary glands
Relaxin Decidual cells Unclear in humans and animals

Secreted hormone Abbreviation From cells Effect
Parathyroid hormone PTH Parathyroid chief cell Calcium:

  • Stimulates Ca2+ release from bone, thereby increasing blood Ca2+
  • Stimulates osteoclasts, thus breaking down bone
  • Stimulates Ca2+ reabsorption in kidney
  • Stimulates activated vitamin D production in kidney

Phosphate:

  • Stimulates PO3−4 release from bones, thereby increasing blood PO3−4.
  • Inhibits PO3−4 reabsorption in kidney, so more PO3−4 is excreted
  • Overall, small net drop in serum PO3−4.

Secreted hormone From cells Effect
Cholecalciferol (vitamin D3) Keratinocytes Cholecalciferol is an inactive form of vitamin D3
Cholecalciferol is converted in the liver first to 25-hydroxycholecalciferol (calcifediol) then to 1,25-dihydroxycholecalciferol (calcitriol), which is the hormonally active metabolite of vitamin D. Calcitriol increases the level of calcium (Ca2+
) in the blood by increasing the uptake of calcium from the gut into the blood, increasing reabsorption of calcium by the kidneys, and possibly increasing the release of calcium into the blood from bone.

Endocrine miscelaneous en.svg

Secreted hormone Abbreviation From cells Effect
Atrial natriuretic peptide ANP Cardiac myocytes Reduce blood pressure by:reducing systemic vascular resistance, reducing blood water, sodium and fats
Brain natriuretic peptide BNP Cardiac myocytes (To a lesser degree than ANP) reduce blood pressure by:reducing systemic vascular resistance, reducing blood water, sodium and fats

Secreted hormone From cells Effect
Thrombopoietin liver and kidney cells stimulates megakaryocytes to produce platelets[5]

In 1998, skeletal muscle was identified as an endocrine organ[13] due to its now well-established role in the secretion of myokines.[13][14] The use of the term myokine to describe cytokines and other peptides produced by muscle as signalling molecules was proposed in 2003.[15]

Signalling molecules released by adipose tissue are referred to as adipokines.

Secreted hormone From cells Effect
Leptin (Primarily) Adipocytes decrease of appetite and increase of metabolism.
Estrogens[16] (mainly Estrone) Adipocytes

  1. ^ Cite error: The named reference :1 was invoked but never defined (see the help page).
  2. ^ Vander, Arthur (2008). Vander’s Human Physiology: the mechanisms of body function. Boston: McGraw-Hill Higher Education. pp. 332–333.
  3. ^ Colorado State University – Biomedical Hypertextbooks – Somatostatin
  4. ^ Endo K, Matsumoto T, Kobayashi T, Kasuya Y, Kamata K (2005). “Diabetes-related changes in contractile responses of stomach fundus to endothelin-1 in streptozotocin-induced diabetic rats”. J Smooth Muscle Res. 41 (1): 35–47. doi:10.1540/jsmr.41.35. PMID 15855738.[permanent dead link]
  5. ^ Jump up to: a b c Kaushansky K (May 2006). “Lineage-specific hematopoietic growth factors”. N Engl J Med. 354 (19): 2034–45. doi:10.1056/NEJMra052706. PMID 16687716.
  6. ^ Jump up to: a b Essentials of Human Physiology by Thomas M. Nosek. Section 5/5ch4/s5ch4_17.
  7. ^ Pentikäinen V, Erkkilä K, Suomalainen L, Parvinen M, Dunkel L (2000). “Estradiol acts as a germinal cell survival factor in the human testis in vitro”. J Clin Endocrinol Metab. 85 (5): 2057–67. doi:10.1210/jcem.85.5.6600. PMID 10843196.
  8. ^ Jump up to: a b c d Bowen, R. (August 6, 2000) Placental Hormones. Colorado State University
  9. ^ Essentials of Human Physiology by Thomas M. Nosek. Section 5/5ch9/s5ch9_13.
  10. ^ Hould F, Fried G, Fazekas A, Tremblay S, Mersereau W (1988). “Progesterone receptors regulate gallbladder motility”. J Surg Res. 45 (6): 505–12. doi:10.1016/0022-4804(88)90137-0. PMID 3184927.
  11. ^ Hormonal Therapy
  12. ^ Massaro D, Massaro GD (2004). “Estrogen regulates pulmonary alveolar formation, loss, and regeneration in mice”. American Journal of Physiology. Lung Cellular and Molecular Physiology. 287 (6): L1154–9. doi:10.1152/ajplung.00228.2004. PMID 15298854.
  13. ^ Jump up to: a b Pedersen BK, Febbraio MA (October 2008). “Muscle as an endocrine organ: focus on muscle-derived interleukin-6”. Physiological Reviews. 88 (4): 1379–406. doi:10.1152/physrev.90100.2007. PMID 18923185.
  14. ^ Ostrowski K, Hermann C, Bangash A, Schjerling P, Nielsen JN, Pedersen BK (December 1998). “A trauma-like elevation of plasma cytokines in humans in response to treadmill running”. The Journal of Physiology. 513 (3): 889–94. doi:10.1111/j.1469-7793.1998.889ba.x. PMC 2231318. PMID 9824725.
  15. ^ Pedersen BK, Steensberg A, Fischer C, et al. (2003). “Searching for the exercise factor: is IL-6 a candidate?”. Journal of Muscle Research and Cell Motility. 24 (2–3): 113–9. doi:10.1023/A:1026070911202. PMID 14609022.
  16. ^ Frühbeck G (July 2004). “The adipose tissue as a source of vasoactive factors”. Curr Med Chem Cardiovasc Hematol Agents. 2 (3): 197–208. doi:10.2174/1568016043356255. PMID 15320786.
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