Chemical Coordination and Integration: Endocrine System


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Chemical Coordination and Integration: Endocrine System

  1. 1. Coordination of activities in humans Nervous system Endocrine system
  2. 2. Nervous System  Transmits electrical impulses  Use the neurons to transmit the signal  Signal transmission is fast  Effect is localized Endocrine System  Transmits chemical biological messengers Impulses  Use the circulatory system to transmit the signal  Signal transmission is slow  Effect is widespread Nervous System vs Endocrine System
  3. 3. Endocrine glands are called ductless glands. They secrete hormones. Hormones are non-nutrient chemicals act as intercellular messengers. They are produced in trace amounts.
  4. 4. HUMAN ENDOCRINE SYSTEM Pituitary Gland Pineal Gland Thyroid Gland Parathyroid Gland Thymus Gland Adrenal Gland Pancreas Gonads (Testis & Ovary)
  5. 5.  Location - Below the thalamus & just above the brainstem  It synthesizes and secretes certain neurohormones.  These hormones regulate the synthesis and secretion of pituitary hormones.  Two types of hormones are produced by hypothalamus: Releasing Hormones Inhibiting Hormones
  6. 6. Synthesizes & releases hypophysiotropic hormones: Thyrotropin-releasing hormone (TRH) Corticotropin-releasing hormone (CRH) Gonadotropin-releasing hormone (GnRH) Growth hormone-releasing hormone (GHRH) Growth hormone-inhibiting hormone (GHIH) Prolactin-releasing factor (PRF) Prolactin-inhibitn hormone (PIH)
  7. 7.  A marble-sized gland at the base of the brain  Location - in the bony cavity called sella tursica.  Controlled by the hypothalamus or other neural mechanisms and therefore the middle man.  Divided anatomically into: (i) Adenohypophysis (ii) Neurohypophysis
  8. 8. Anterior Pituitary Growth hormone (GH) Thyroid stimulating hormone (TSH) Adrenocorticotrophic hormone (ACTH) Prolactin (PRL) Luteinizing hormone (LH) Follicle stimulating hormone (FSH) Posterior Pituitary Oxytocin Vasopressin or Anti-diuretic hormone
  9. 9. Hormone Target(s) Function GH All cells in the body Stimulates growth and repair. Hyper-secretion of GH leads to Gigantism and low secretion of GH results stunted growth called Dwarfism. TSH Thyroid Stimulates the thyroid gland to secrete the hormone thyroxine (T4) and triiodothyronine (T3). It regulates the body's metabolic activities. ACTH Adrenals Stimulates the adrenal gland to produce glucocorticoids. PRL Breasts Stimulates the growth of the mammary glands and formation of milk. LH Testes (men) Ovaries (women) LH and FSH are called gonadotrophins as stimulate gonadal activity. LH stimulates the synthesis and secretion of hormones called androgens from testis. Stimulates the ovaries to produce oestrogen and progesterone.
  10. 10. FSH Ovaries (women) Stimulates growth and development of the ovarian follicles in females. MSH Melanocytes in skin Stimulate the production and release of melanin which regulates pigmentation of the skin. Oxytocin Uterus Breasts Stimulates a vigorous contraction of uterus at the time of child birth, and milk ejection from the mammary gland. Vasopressin (ADH) Kidneys Stimulates reabsorption of water and electrolytes by the distal tubules and reduces loss of water through urine (Diuresis).
  11. 11.  The pineal gland is reddish-gray and about the size of a grain of rice in humans.  Location - on the dorsal side of forebrain.  Hormone – Melatonin  Function - It affects the modulation of sleep patterns in the circadian rhythms and seasonal functions.  It helps in maintaining the body temperature.  It influences metabolism, pigmentation, the menstrual cycle as well as our defense capability. Sources: t/ciencia/ciencia_brain01.htm
  12. 12.  Location - Thyroid is a small, butterfly-shaped gland located at the base of the neck below the thyroid cartilage.  Composition - It is composed of two lobes located on either side of the trachea.
  13. 13.  The thyroid gland is composed of follicles and stromal tissues.  Each thyroid follicle is composed of follicular cells, enclosing a cavity.  Thyroid hormones: Tetraiodothyronine or thyroxine (T4) Triiodothyronine (T3)
  14. 14. Function of Thyroid hormones Regulation of the basal metabolic rate. Control the metabolism of carbohydrates, proteins and fats. Maintenance of water and electrolyte balance. Secrete thyrocalcitonin (TCT) which regulates the blood calcium levels. Support the process of red blood cell formation.
  15. 15.  Hypothyroidism is a condition characterized by abnormally low thyroid hormone production.  Hyperthyroidism is a condition in which the thyroid gland produces and secretes excessive amounts of thyroid hormones, triiodothyronine (T3) and/or thyroxine (T4). Goiter Hyperthyroidism Hypothyroidism in Man Hypothyroidism In Child
  16. 16.  Location - Two pairs of parathyroid glands located behind the outer wings of the thyroid.  It secrete a peptide hormone called parathyroid hormone (PTH).  The secretion of PTH is regulated by the circulating levels of calcium ions.  Function - PTH regulates the amounts of calcium, phosphorus and magnesium in the bones and blood.  It increases the blood Ca2+ levels and maintain calcium balance in the body.
  17. 17.  Location - Dorsal side of the heart and the aorta  Hormone –Thymosins  Role - Plays an important role in the development of the immune system.  Role ofThymosin :  Provide cell-mediated immunity  Promote production of antibodies to provide humoral immunity o Thymus is degenerated in old individuals
  18. 18. Location - anterior part of each kidney Composed of two types of tissues:  Centrally located tissue adrenal medulla  Outside tissue adrenal cortex Source :
  19. 19. Adrenal Gland Adrenal Medulla Adrenaline or Epinephrine Noradrenaline Norepinephrine Adrenal Cortex Corticoids
  20. 20. ADRENAL MEDULLA  Adrenal medulla releases the catecholamines: i)Adrenaline or Epinephrine ii)Noradrenaline or Norepinephrine  These hormones are released in stressful situations, hence called emergency hormones or hormones of Fight or Flight.  These hormones increase the heart beat, alertness, pupilary dilation, piloerection (raising of hairs), sweating etc.
  21. 21. ADRENAL CORTEX  Adrenal cortex divided into three layers: Zona reticularis (inner layer) Androgens zona fasciculata (middle layer) Glucocorticoids Zona glomerulosa (outer layer) Mineralocorticoids
  22. 22. Function of Adrenal Medulla and Cortex Sources:
  23. 23.  The pancreas is a flattened organ lies in the abdomen, posterior and slightly inferior to the stomach.  It is a composite gland and acts as both exocrine and endocrine gland.  Histologically, it consists of islets of Langerhans and acini cells.
  24. 24. Islets of Langerhans α-cells Glucagon β-cells Insulin
  25. 25. Source:
  26. 26.  Location - Present in the scrotal sac (outside abdomen) of male.  Testis performs dual functions as a primary sex organ as well as an endocrine gland.
  27. 27. Composed of seminiferous tubules and interstitial tissue. The Leydig cells or interstitial cells produce a hormones called androgens mainly testosterone. During puberty, testosterone helps to bring about the following physical changes that turn a boy into an adult male:  Increase in muscle mass and strength, and increase in height.  Growth of facial and pubic hair,  Deepening of the voice, male hair patterns,  Sperm production (spermatogenesis)
  28. 28.  Location -A pair of ovaries located in the abdomen of female.  It is the primary female sex organ which produces one ovum during each menstrual cycle.  It produces two groups of steroid hormones : Estrogen and Progesterone.
  29. 29. Estrogen  Estrogen is synthesised and secreted by ovarian follicles.  It is responsible for development of growing ovarian follicles, the appearance of female secondary sex characteristics at puberty such as high pitch of voice, development of mammary gland. Progesterone  Progesterone is secreted by corpus luteum.  It regulates female sexual behaviour.  It prepares the uterus for pregnancy, and the mammary glands for lactation.  Progesterone supports pregnancy.
  30. 30.  Atrial wall of heart secretes peptide hormone atrial natriuretic factor (ANF), which decreases blood pressure.  Juxtaglomerular cells of kidney produce a peptide hormone erythropoietin which stimulates erythropoiesis (formation of RBC).  Gastro-intestinal tract secrete four major peptide hormones:  Gastrin,  Secretin,  Cholecystokinin (CCK)  Gastric inhibitory peptide (GIP).
  31. 31.  Gastrin acts on the gastric glands and stimulates the secretion of hydrochloric acid and pepsinogen.  Secretin acts on the exocrine pancreas and stimulates secretion of water and bicarbonate ions.  Cholecystokinin (CCK) acts on both pancreas and gall bladder and stimulates the secretion of pancreatic enzymes and bile juice, respectively.  Gastric Inhibitory Peptide (GIP) inhibits gastric secretion and motility.