ENDOCRINE SYSTEM

2. ENDOCRINE SYSTEM

3. Endocrine System • Introductions :- • The aim of endocrine system is to maintain the co-ordination among various systems of body and with environment also. The study of endocrine, system is known as endocrinology. • The endocrine system consists of a number of ductless gland which manufacture certain chemical substance that take an essential part in the life processes of the body. • This system contains glands which secrets hormones which guides & control the growth, multiplication, diffrentiation,

4. & metabolic activities of various tissues & system and there by bring about correct physiological balance between them. Although Endocrines are ideal coordinating system of sustained nature, they are not efficient enough where quickness ,exact localization etc. are required.

5. The important endocrine glands includes :- 1) Hypothalamus 2) Pineal gland 3) Pituitary Gland 4) Thyroid 5) Parathyroid 6) Thymus 7) Endocrine Pancreas 8) Adrenal gland 9) Gonads

6. Definition of Hormone :- It is a high molecular weight chemical messenger which may be steroid in nature or non steroid (protein, glycoprotein, peptide, amino acid and amines.) • Released directly to blood from the gland the gland taken away to a target organ

8. Contents • Introduction of Endocrine system • Pituitary gland • Thyroid gland • Parathyroid gland • Pancreas • Thymus • Pineal gland • Adrenal cortex • Adrenal Medulla • Gonads (Testis + Ovary ) • Bibliography

9. Pituitary gland

11. ANATOMY • SITUATION=> Pituitary is situated at the base of the brain in the SELLATURCICA of the sphenoid bone. • DIVISION/PARTS=> Physiologically the Pituitary gland is divided into two portions namely; • The anterior Pituitary or Admonypophsis. • The posterior Pituitary or Neurohypophysis. • Between the teo portions, there is a small, relatively a vascular zone called pars intermedia. • Pars intermedia is rudimentary in human &functional in animals.

12. SITUATION OF PITUITARY GLAND

13. PARTS=> Ant Pituitary - 1) Pars Distills 2) Pars Tubercles 3) Pars Intermedi => Post Pituitary – 1)Pars Nervosa 2)Neural Stalk 3)The Median Eminence

14. DEVELOPMENT => Ant Pituitary is ECTODERMAL in origin while posterior Pituitary is ENDODERMAL in origin The anterior &intermediate lobe of the Pituitary arise in the embryo from RATHKE’SPOUCH’ an evagination from the roof of the pharynx but is closely adherent to the post lobe in the adult.

15. HISTOLOGY => ANTERIOR PITUITARY- There is two types of cells present in anterior pituitary. 1) Chromophobe cells 2) Chromophill cells CHROMOPHOBE CELLS => Thee cells are non secreting in nature but are believed to be the precursor of chromophill cells. They do not possess granules & stain poorly. These cells form about 50% of total cells of adinohypophysis. ROMEIS Classified the chromophobss as gamma cells.

16. CHROMOPHILL CELLS => Chromophill cells contain large number of granules & they have got affinity aowards dyes. • These cells are of two types • *Alpha Cells 35% • *Beta Cells 15% • Alpha Cells are stained by the acid by dye so named as Acidophil Cells. • Beta Cells are stained by the basic dye so named as Basophilic Cells

17. Chromophill Cells are secretary in nature. Classified into 5 groups depending upon this nature. a) Somatotropes - Growth Hormone b) Corticotropes - Adrenocorticotropic hormone c) Thyrotropes - Thyroid stimulating Hormone d) Gonadotropes - Follicle stimulating Hormone & Luteinizing Hormone e) Lactotropes - Prolactin About 30 to 40 % of the cromophill cells are somatotropes. So pituitary tumors that secrete large quantities of human growth hormone are called ACIDOPHILLIC TUMORS

18. POSTERIOR PITUITARY=> • Posterior pituitary consists following cells:- • A)Pituiticytes - These Cells contain yellow – brown granules of neurosecretion. • 1. Adenopituiticytes • 2. Micro Pituiticytes • 3. Fibro Pituiticytes • 4. Reticulo Pituiticytes • B)Non medullated Nerve fibers C)Mast cells D)Herring bodies

19. FUNCTION => Anterior pituitary secretes following Hormones. 1. Growth Hormone ( G.H.) 2. Thyroid Stimulating Hormone (T.S.H.) 3. Adrenocorticotropic Hormone (A.C.T.H.) 4. Follicle Stimulating Hormone (F.S.H.) 5. i) Luteinizing Hormone (L.H.) - in Females ii) Interstitial cell stimulating Hormone (I.C.S.H. – in males. 6. Prolactin (PRL) 7. b– Lipotropin

20. ACTION OF EACH HARMONE => GROWTH HARMONE =>it is secreted by acidophills of anterior pituitary which are also known as SOMATOTROPES, That is why it is also called SOMATOTROPIC HORMONE (S.T.H.) -Human Growth Hormone is composed of 180 Amino Acid. -Growth Hormone is protein in nature having a single chain polypeptide

21. ACTION OF GROWTH HORMONE => -Growth Hormone increases the size & number of cells by increasing the mitotic divisions. - Thus it is important for the general growth of body. - G.H. also acts on the metabolism of all the three major types of Foodstuff. E.g.. – Protein, Lipid & Carbohydrate.

22. Metabolic effect of Growth Hormone => G H increases the synthesis of Proteins, Mobilization of lipid & Conservation of glucose. • A) Effect of Growth Hormone on Protein metabolism => • Increases the amino acid transport through the cell membrane so the synthesis of protein is increased. • It synthesized more protein by activating ribosome's through the process of RNA translation. • It increases transcription of DNA to RNA, which promotes the synthesis of protein. • Also decreases catabolism of Protein.

23. Effect of GH. on the Fat Metabolism => Growth Hormone causes mobilization of fats from adipose tissue. Because of this the mobilized fat is transported in the plasma as non-esterified fatty acids During utilization of fatty acids, a lot of ACETOACITIC ACID is formed by the liver. By releasing of this acetoacetic acid in body fluids, KETOSIS Occur. Sometimes excessive mobilization of fat from the adipose tissue causes accumulation of fat in liver Resulting in FATTY LIVER.

24. Effect of G.H. on Carbohydrate Metabolism => • The main action of G.H. on Carbohydrates is conservation of glucose by the following process. • By decreasing the peripheral utilization of glucose for the production of energy. • By increasing the concentration of glycogen in the cells. • Decreased uptake of glucose by the cells.

25. Effect of G.H. on Skeletal growth => • Stimulates the multiplication of the epiphyseal cartilage &thus increase the length of the cartilage bone. TRANSPORT OF G.H. G.H. transported in blood by loose binding with plasma protein. CONTROL OF G. H. SECRETION :- From the Hypothalamus, growth Hormone inhibiting hormone (G.H.I.H) i.e. somatostatin is secreted & is delivered to the adenohypophysis via the “Portal System”. Somatostatin inhibits G.H. secretion. Adrenalin, progesterone & high level of FFA in the plasma cause inhibition of G.H. From the hypothalamus, growth hormone releasing &causes stimulation of G.H. secretion. Secretion of G.H. is stimulated in various conditions, most notably during sleep, but also in such condition like exercise , anxiety & hypoglycemia.

26. MECHANISM OF ACTION :- • G.H. stimulates the production of a substance called somatomedine. • Somatomidine causes growth in the tissue. • Lack of G.H. causes lack of somatomedine leads to the Dwarfism.

27. THYROID STIOMULATING HORMONE • The TSH is synthesized by the thyrotrophs which are basophilic cells. • It is a glycoprotein. • Major Action of the TSH is to stimulate the thyroid gland to produce the thyroid Hormones. • TSH causes increased vascularity & cellular growth of the thyroid gland. • From the Hypothalamus Thyrotropin releasing hormone, TRH is secreted.

28. TRH acts on Pituitary thyrotropin & stimulates them to secrete TSH. • TSH increased the size & secretory activity of cells. • It stimulate thyroglobulin secretion into the follicles. • It increase iodination of tyrosine &coupling to form the hormones. • The immediate effect of administration of TSH, if to release thyroxin within 30 minutes.

29. A.C.T.H. It is a polypeptide containing 39 Amino Acid. Synthesized by Corticotroph cells. Precursor molecule of ACTH is cleared to produce. 1. Mature ACTH Molecule 2.16 k Fragment 3. b(Beta) lipoprotein => g (gama) lipoprotein => b endorphin *Endorphin is an important agent produced by our body, which inhibits pain.

30. Major function of ATCH is to release a. Cortisol b. Adrenal Androgens - It also acts on melanocytes * There are few chemical similarities between A.T.C.H. & M.S.H. -CRH( corticotrophin releasing hormone ) of hypothalamus has a very strong influence on ACTH secretion. - Stress of all kinds causes stimulation of A.C.T.H.

31. F.S.H. *In Females, the FSH causes growth & maturation of the Graffian follicle, the growing follicle in turn secretes estrogen. *In males, the FSH helps in spermatogenesis & normal functioning of the seminal vesicles.

33. LUTEINIZING HORMONE ACTION IN MALES => In males, this hormone is known as interstitial cell stimulating hormone ( I.C.S.H.) This hormone is essential for the secretion of testosterone from Leydig cells. ACTION IN FEMALES=> This is responsible for Ovulation. -Necessary for the formation of corpus luteum. -It activities the secretory functions of corpus luteum. - It causes naturation of vesicular follicle into guaffian follicle along with follicle stimulating hormone.

34. PROLACTIN • -This hormone is secreted by lactotrophs. • -Prolactin contains 198 amino acids. • -Human PRL causes initiation of milk formation & -its maintenance in the female breast. • -Prolactin Receptors are found in the breast & gonads. • From Hypothalamus released two factors :- • i) PIF ( probating inhibitory factor )=> Inhibits the secretion of PRL. e.g. – Dopamine. • PRF ( prolactin releasing factors )=> • During pregnancy excess estrogen derived from placenta which result the great rise of prolactin.

35. b-LIPOPROTEIN • This is Polypeptide of 31 amino acid. • It mobilizes fat from adipose tissue & promotes lipolysis. • It forms the precursor of endorphins.

36. REGULATION OF GLAND :- • Regulation of Secretion of Ant Pituitary=> • Secretion of ant pit is regulated by hypothalamus. • Hypothalamus is connected with anterior pituitary through Hypothalamo-hypophyseal portal system.

38. Hypothalamus secretes some releasing & inhibitory factors, there hormone are secreted in Hypothalamus & transported to the ant pituitary through hypothalamohypophyseal portal vessels. • Some special nerve cells controls the synthesis & secretion of these factors. • There hormone are immediately taken into the hypothalamohypophyseal portal system & transported directly to the anterior pituitary. • Growth hormone inhibitory (Somatostatin)& Prolactin inhibitory hormone (Dopamine) are inhibitory factors.

39. REGULATION OF SERETION OF POSTERIOR PITUITARY : Posterior pituitary hormones are secreted by hypothalamus & transported to posterior pituitary. Hormones are transported through the nerve fibers of hypothalamohypophysial tract. Hormones are stored at the nerve endings , whenever impulses reach the posterior pituitary from hypothalamus hormones are released from the nerve endings.

40. HORMONES OF POSTERIOR PITUITARY : Anti diuretic hormone (ADH) Oxytocin ADH : ADH is synthesized mainly in the supra optic nucleous, situeted in the anterior part of hypothalamus. ADH is also called vasopressin because , it producess construction of blood vessels. ADH is a polypeptide containing 9 amino acid.

41. FUNCTIONS OF ADH:: The major function of ADH is retention of water by acting on kidneys. Though ADH prevent the loss of large amount of water through urine or it concentrate the urine. ADH increases the permeability of membrane of DCT & collecting duct. Large amount of ADH causes constriction of blood vessels due to this the blood pressure is increased.

42. Control of ADH secretion: Osmolality of blood ;In the condition of water deprivation (No drinking water for long time) the osmotic tension of blood increased. The hypertonic blood stimulate osmoreseptores present in hypothalamus. Osmoreceptores send the nerve impulses to the supra optic nuclei of hypothalamus. Now hypothalamus secretes the ADH .

43. HYPOTHALAMUS Growth hormone Inhibitory hormone Growth hormone Releasing hormone Stimulation Inhibition Anterior Pituitary Growth hormone Liver Tissue Somatomedin

44. OXYTOCINE:: It is secreted by the Para ventricular nucleolus in the hypothalamus. Oxidizing is the polypeptide having 9 amino acids. Oxytocine acts on mammary gland & uterus. ACTION ON MAMMARY GLAND : It Causes contraction of the myoepithilial cells of the matured female breast so that milk ejection occurs.

45. ACTION OF UTERUS : Action of oxytocine on non pregnant uterus is to facilitates the transport of sperms through the female genital tract unto fallopian tube by producing the uterine contraction during the sexual intercourse. Action of oxytocine on pregnant uterus is to cause contraction of uterine muscles during labor. this helps in the delivery of foetus.

46. CONTROL OF OXYTOCINE SECRETION ; During suckling impulses arise at the nipple which initiates a reflex ultimately results into oxytopsin secretion leading to milk ejection. Rubbing of the female external genitalia also causes the initiation of the reflex ultimately ending end oxytosin secretion. During parturition large quantity of oxytocin is realized by means of positive feedback.

47. APPLIED PHYSIOLOGY 1) Hyperactivity of Ant. Pituitary A) Acromegaly B) Gigantism C) Acromegalic gigantism D) Cushing’s 2) Hypoactivity of Ant. Pituitary A) Dwarfism B) Acromicria C) Simmonds’ or Pituitary cachexia

48. Hypoactivity of post. Pituitary – Diabetes insipidus Hyperactivity of Post. Pituitary – Syndrome of inappropriate hypersecretion of ADH (SIADH) Hypoactivity if ant. Pituitary together and Hypoactivity of post. Pituitary – Dystrophia adiposogenital or Frolich’s syndrome

49. GIGANTISM The excessive growth of the body is called gigantism. This occurs due to the hypersecretin of G.H. in children. The subjects look like the giants and average height of about 7–8 feet. Causes of gigantism – Gigantism is due to the hypersecretion of G.H. in childhood or in the pre-adult life before the fusion of epiphysics of bone the shaft. The hypersecretion of G.H. may be because of tumor of acidophil cells in the ant. Pituitary.

50. Symptoms of gigantism The general over growth of the person leads to the development of a huge stature and a height of more than 7-8 feet. The limbs are disproportionately long. The giants are hyperglycemic & they develop glycosuria and pituitary diabetes. The hyperglycemia causes constant stimulation of  cells of islets of langerhans in the pancreas and release of insulin. However the over activity of  cells of Langerhans in pancreas leads to degeneration of these cells and deficiency of insulin’s. Ultimately diabetes mellitus is developed.