Understanding the Endocrine System: Functions, Glands, and Regulation

1. Chapter 18: Endocrine Glands AP2 Chapter 18

2. Chapter 18 Outline • Fxns of the Endocrine System • Pituitary Gland & Hypothalamus • Thyroid Gland • Parathyroid Glands • Adrenal Glands • Pancreas • Hormonal regulation of nutrients • Hormones of the reproductive system • Hormones of the pineal body • Hormones of the Thymus • Hormones of the GI tract • Hormone-like Substances • FX of aging on the endocrine system AP2 Chapter 18

3. Understanding the Endocrine System • ES’s regulation of body fxns: • Anatomy of each gland & its location • Hormones secreted by each gland • Target tissues & their responses to the hormone • Regulation of those hormones secretion • Consequences & causes of hypersecretion/hyposecretion of the hormone AP2 Chapter 18

4. I. Fxns of the Endocrine System (ES) AP2 Chapter 18

5. Main regulatory fxns of the ES I. Fxns of the Endocrine System • Metabolism & tissue maturation • Ion regulation • Water Balance • Immune System regulation • Heart rate & BP regulation • Control of bld glucose & other nutrients • Control of reproductive fxns • Uterine contractions & milk release AP2 Chapter 18

6. I. Fxns of the Endocrine System Main regulatory fxns of the ES Heart rate & BP regulation Helps to prep the body for physical activity Control of bld glucose & other nutrients In the bld Control of reproductive fxns Controls the development & fxns of reproductive system in both males & females Uterine contractions & milk release During childbirth & after birth • Metabolism & tissue maturation • Regulated rate of metabolism • Influences the maturation of tissues (i.e. nervous system) • Ion regulation • Regulate blood pH • Na, K, & Ca [ ] in blood • Water Balance • Controlling solute [ ] in the blood • Immune System regulation • Controlling the prod’n of immune cells AP2 Chapter 18

7. II. Pituitary Gland & Hypothalamus AP2 Chapter 18

8. II. Pituitary Gland & Hypothalamus Figure 18.1 Pg. 610 Hypothalamus: • Major site where nervous system & ES interact • Hypo regulates secretions of the Posterior Pituitary • Hormones, sensory information that enters the CNS & emotions in turn influence the activity of the hypothalamus Pituitary Gland: • Secretes 9 major hormones that regulate numerous body fxns & secretory activities of other glands • Divided into 2 parts: • Posterior Pituitary • Secretions = neurohormones • Anterior Pituitary • 3 regions: • Pars tuberalis • Pars intermedia • Pars distalis • Hormones from AP are not neurohormones • Pg 611 • Figure 18.2 AP2 Chapter 18

9. II. Anterior Pituitary & Hypothalamus Anterior Pituitary • Hypothalamohypophysial Portal System • Extends from the hypothalamus to the AP so that neurohormones produced by the hypothalamus to stimulate or inhibit the cells of the AP • THUS the hypothalamus controls the AP AP2 Chapter 15: The Special Senses

10. Hypothalamus Low Bld Glucose Stress High Thyroid hormone level Low Thyroid hormone level High Bld Glucose Growth hormone releasing hormone Growth hormone inhibiting hormone Thyroid releasing hormone Corticotropin releasing hormone Gonadotropin releasing hormone Prolactin releasing hormone Anterior Pituitary Anterior Pituitary Anterior Pituitary Anterior Pituitary Anterior Pituitary Growth Hormone Thyroid Stimulating Hormone Adrenocorticotropic Hormone LH & FSH Prolactin

11. II. Posterior Pituitary & Hypothalamus Posterior Pituitary • Neurohormones released from PP are not made by the PP. These hormones that are stored in the PP are originally made in the hypothalamus. • The neurosecretory cells of the hypothalamus have axons that extend to the PP. Neurohomeones are prod’d in these neurosecretory cells and travel via vesicle toward the axon terminal. AT the axon terminal they are stored in secretory vesicles. The axon terminals are buried in the PP. Action potentials cause the release of the neurohormones from the axon terminal so that they can enter the blood stream. AP2 Chapter 15: The Special Senses

12. Hypothalamus Low Bld Glucose Stress High Thyroid hormone level Low Thyroid hormone level High Bld Glucose Posterior Pituitary Growth hormone releasing hormone Growth hormone inhibiting hormone Thyroid releasing hormone Corticotropin releasing hormone Gonadotropin releasing hormone Prolactin releasing hormone Antidiuretic hormone Oxytocin Anterior Pituitary Anterior Pituitary Anterior Pituitary Anterior Pituitary Anterior Pituitary Growth Hormone Thyroid Stimulating Hormone Adrenocorticotropic Hormone LH & FSH Prolactin

13. Hypothalamus Low Bld Glucose Stress High Thyroid hormone level Low Thyroid hormone level High Bld Glucose Posterior Pituitary Growth hormone releasing hormone Growth hormone inhibiting hormone Thyroid releasing hormone Corticotropin releasing hormone Gonadotropin releasing hormone Prolactin releasing hormone Antidiuretic hormone Oxytocin Anterior Pituitary Anterior Pituitary Anterior Pituitary Anterior Pituitary Anterior Pituitary Target: Uterus & Mammary Glands Target: Kidney Growth Hormone Thyroid Stimulating Hormone Adrenocorticotropic Hormone LH & FSH Prolactin • Response: • Increased water reabsorption & less urine prod’n • Response: • Female: Increased uterine contraction and increased milk expulsion from the mammary glands

14. II. Anterior Pituitary Gland • Hormones are proteins, glycoproteins, or polypeptides labeled Tropic Hormones • Transported via the cardiovascular system • Half life of these hormones is minutes • Bind to membrane bound receptors on target tissues • Most hormones are secreted by their own separate cell types. AP2 Chapter 15: The Special Senses

15. Hypothalamus Low Bld Glucose Stress High Thyroid hormone level Low Thyroid hormone level High Bld Glucose Posterior Pituitary Growth hormone releasing hormone Growth hormone inhibiting hormone Thyroid releasing hormone Corticotropin releasing hormone Gonadotropin releasing hormone Prolactin releasing hormone Antidiuretic hormone Oxytocin Anterior Pituitary Anterior Pituitary Anterior Pituitary Anterior Pituitary Anterior Pituitary Target: Uterus & Mammary Glands Target: Kidney Growth Hormone Thyroid Stimulating Hormone Adrenocorticotropic Hormone LH & FSH Prolactin • Response: • Increased water reabsorption & less urine prod’n Target Tissue: Gonads Target Tissue: Mammary glands Ovaries Target Tissue: Most tissues Target Tissue: Thyroid tissue Target Tissue: Adrenal cortex • Response: • Female: Increased uterine contraction and increased milk expulsion from the mammary glands • Response: • Stimulates synthesis and secretion of thyroid hormones from the thyroid • Response: • Stimulate formation of gametes (sperm/egg) • Control prod’n of reproductive hormones (Ovaries: estrogen & progesterone) (Testis: testosterone) • Response: • Stimulates the growth of most tissues • Important in the regulation of nutrient levels • Regulation of metabolism • Increases movement of AA into the cells • Increases lipolysis • Increases FA release from Adipocytes • Increased glucose synthesis in the liver • Response: • Increased hormone secretion from the adrenal cortex • Response: • Female: milk prod’n in mammary glands and ovaries increase progesterone secretion • Males: Unknown fxn

16. Hypothalamus Low Bld Glucose Stress High Thyroid hormone level Low Thyroid hormone level High Bld Glucose Posterior Pituitary Growth hormone releasing hormone Growth hormone inhibiting hormone Thyroid releasing hormone Corticotropin releasing hormone Gonadotropin releasing hormone Prolactin releasing hormone Antidiuretic hormone Oxytocin Anterior Pituitary Anterior Pituitary Anterior Pituitary Anterior Pituitary Anterior Pituitary Target: Uterus & Mammary Glands Target: Kidney Growth Hormone Thyroid Stimulating Hormone Adrenocorticotropic Hormone LH & FSH Prolactin Target Tissue: Gonads Target Tissue: Most tissues Target Tissue: Thyroid tissue Target Tissue: Adrenal cortex Other related substances b-endorphins Lipotropins Melanocytestimulting hormone Target Tissue: Brain- rest unknown Target Tissue: Fat tissue Target Tissue: Melanocytes • Response: • Increased fat brkdwn • Response: • Increased melanin prod’n Darker skin • Response: • Painkiller in the brain, Inhibition of GnRH

17. III. Thyroid Gland AP2 Chapter 18

18. III. Thyroid Gland Pg 620 Figure 18.8 • Location: • Lateral upper portion of the trachea just inferior to the larynx • One of the largest endocrine glands @ ~20g • Highly Vascular with numerous follicles whose centers are filled w/proteins called Thyroglobin (Prod’d by follicular cells) • Follicles store large amounts of thyroid hormones as part of thyroglobin(T3 & T4) • Parafollicular cells prod calcitonin AP2 Chapter 18

19. III. Thyroid GlandThyroid Hormones • 2 types • Triiodothyronine [T3] • Tetraiodothyronine [T4] • 10% of thyroid product • A.k.a. Thyroxine • 90% of thyroid product • XS thyroid hormone is stored w/in the follicles • TSH causes the release of T3 & T4 from follicles • Major component of T3 & T4 is iodine wh/is why it is so important to have in your diet. • These are also lipid soluble hormones • 70-75% in blood must be bound to transport protein called: Thyroxine-binding protein • Creates a large reservoir of T3 & T4. • 33-44% of the T3 is converted into T4 in the tissues b/c T3 is major hormone that interacts with target & is several times more potent. • Rapidly metabolized and excreted in urine or bile AP2 Chapter 18

20. Thyroid Gland Follicular Cells Parafollicular Cells Thyroid Hormone T3 & T4 Calcitonin • Target tissue: • Bone • Decreases osteoclast activity • Lengthens life of osteoblast Target tissue: Most cells in the body • Response: • Essential for the normal process of growth and maturation • Increase metabolic rate: • Increase breakdown of sugar, fat, and protein • Increase Na/K pump activity • Alter the # and activity of mitochondria • Response: • Increases bone deposition • Decreases the amount of calcium and phosphate in the blood.

21. IV. Parathyroid Glands AP2 Chapter 18

22. IV. Parathyroid Glands • 4 small units embedded in the back of the thyroid • 2 cell Types • Chief Cells • Oxyphils Figure 18.11 AP2 Chapter 18

23. Parathyroid Gland Chief Cells Oxyphils Parathyroid Hormone UNKNOWN Target tissue: Bone, Kidney, Small Intestine • Response: • Increased bone breakdown by osteoclasts • Increased reabsorption of calcium in the kidneys & small intestine • Increased vitamin D synthesis • Increased Blood Calcium levels

24. V. Adrenal Glands AP2 Chapter 18

25. V. Adrenal Glands • Located above the kidney surrounded by abundant adipose tissue & CT capsule w/an abundant blood supply. • 2 major regions • Cortex • Outer edge • 3 layers • Zona glumerulosa (outer) • Zona fasiculata (middle) • Zona reticularis (inner) • Medulla • Inner core • Each of the regions & layers is fxnally & structurally specialized AP2 Chapter 18

26. Adrenal Gland Adrenal Medulla Adrenal Cortex Epinephrine & Norepinephrine Zona Reticularis Zona Fasiculata Zona Glumerulosa Target tissue: Heart Blood vessels Liver Fat cells • Response: • Preparation for physical activity • Increased cardiac output • Increased blood flow to skeletal muscle and heart • Vasoconstriction of blood vessels to visceral organs • Increased release of glucose and fatty acids

27. V. Adrenal GlandsAdrenal Cortex • 3 types of steroid hormones are prod’d here • All have similar structure to steroids & are derived from cholesterol • B/c they are lipid soluble • They are not stored in the cell but synthesized as needed • Transported in the blood via transport proteins • Metabolized in the liver & excreted in bile & urine • Bind to intracellular receptors to stimulate the synthesis of specific proteins responsible for prod’ing cellular responses AP2 Chapter 18

28. V. Adrenal GlandsAdrenal Cortex Hormones are made as needed not stored • Zona Glomerulosa • Mineralcorticoids • Zona Faciculata • Glucocorticoids • Zona Reticularis • Adrenal Androgens Hormones are made as needed not stored AP2 Chapter 18

29. Adrenal Gland Adrenal Medulla Adrenal Cortex Epinephrine & Norepinephrine Target tissue: Heart, Blood vessels, Liver & Fat cells Zona Glumerulosa Zona Fasiculata Zona Reticularis • Response: • Preparation for physical activity • Increased cardiac output • Increased blood flow to skeletal muscle and heart • Vasoconstriction of blood vessels to visceral organs • Increased release of glucose and fatty acids Mineralcorticoids Glucocorticoids Adrenal Androgens Target tissue: Most Tissue Target tissue: Kidney Target tissue: Many Tissues • Response: • Increased Na+, K+, and H+ excretion by the kidney • Enhanced water reabsoption • Response: • Increase in fat and protein breakdown • Increase in glucose prod’n • Inhibition of immune response and decreased inflammation • Response: • Males: Minor importance • Females: development of secondary sex characteristics

30. VI. Pancreas AP2 Chapter 18

31. VI. Pancreas • Lies btwn the greater curvature if the stomach & duodenum (beginning of the small intestine) • Head: lies close to the duodenum • Body: extends toward spleen • Fxns as both an endocrine and exocrine gland • Exocrine: • Acini cells prod pancreatic juice & a duct which carries the pancreatic juice into the small intestine Pg 634 Fig 18.16 • Endocrine: • Pancreatic islets secrete hormones into the circulatory system

32. VI. Pancreas Pancreatic Islets • Alpha (a) cells • Secrete glucagon • Small peptide hormone • 20% of cells • Beta (b) cells • Secrete insulin • Small protein w/2 polypeptide chains • 75% of cells • Delta (d) cells • Secrete somatostatin • Small polypeptide hormone • Remaining 5% of cells AP2 Chapter 18

33. Endocrine Gland Exocrine Gland Pancreas Secretes enzymes onto the surface of the small intestine Pancreatic Islets b-cells a-cells d-cells Low Blood Glucose Certain AA Sympathetic stimulation High Blood Glucose Glucagon Target tissue: Liver Adipocytes • Response: • Rapid increase in glycogen breakdown & increase in blood glucose levels • Increased glucose formation from AA and some fats • Increased metabolism of FA’s resulting in increased ketones in the blood • Response: • Causes the breakdown of fats from adipocytes

34. Endocrine Gland Exocrine Gland Pancreas Secretes enzymes onto the surface of the small intestine Pancreatic Islets b-cells a-cells d-cells Increased Blood Glucose Certain AA GI-tract hormones Low blood glucose Somatostatin Glucagon Somatostatin Insulin Target tissue: • Nervous System • Adipocytes • Skeletal muscle • Cardiac Muscle • Cartilage • Bone • Fibroblasts • Leukocytes • Mammary glands • Liver • Response: • Increased glucose uptake • Increased glycogen synthesis • Increased fat synthesis • Increased FA uptake • Increased glycolysis • Response: • Increased glycogen synthesis • Increased glycolysis • Response: • Increased glucose uptake in the satiety center • Response: • Increased glucose uptake • Increased glycogen synthesis • Increased uptake of certain AA’s

35. Endocrine Gland Exocrine Gland Pancreas Secretes enzymes onto the surface of the small intestine Pancreatic Islets a-cells b-cells d-cells Somatostatin Target tissue: a & b Cells of the pancreas • Response: • Inhibition of insulin and glucagon secretion

36. VII. Hormonal Regulation of Nutrients AP2 Chapter 18

37. VII. Hormonal Regulation of Nutrients Pg 639 AP2 Chapter 18

38. Pg 640 VII. Hormonal Regulation of Nutrients AP2 Chapter 18

39. VIII. Hormones of the Reproductive System AP2 Chapter 18

40. ReproductiveSystem Female Ovary Male Testis Testosterone Inhibin Target tissue: Most cells Target tissue: Anterior Pituitary • Response: • Aids in spermatogenesis • Development of the genitalia • Maintenance of fxnal reproductive organs • 2ndary sex characteristics • Sexual Behavior • Response: • Inhibits FSH

41. ReproductiveSystem Female Ovaries Male Testis Estrogen Progesterone Inhibin Relaxin Target tissue: Most cells Target tissue: Most cells Target tissue: Anterior Pituitary Target tissue: Connective Tissue • Response: • Uterine and mammary gland development and fxn • Maturation of genitalia • 2ndary sex characteristics • Sexual behavior • Menstrual Cycle • Response: • Uterine and mammary gland development and fxn • Maturation of genitalia • 2ndary sex characteristics • Menstrual Cycle • Response: • Inhibits FSH • Response: • Increases flexibility of CT in pelvic area, especially in the symphysis pubis Female Placenta LH-Like Substance • Response: • Maintains pregnancy Increasing amounts of estrogen & progesterone Female Placenta & Ovaries • Response: • Necessary to maintain pregnancy

42. IX. Hormones of the Pineal Body AP2 Chapter 18

43. IX. Hormones of the Pineal Body Fxn of PB in Humans is still actually unclear but when there are tumors 1. early sexual development or 2. retarded development of reproductive system Pg 642

44. X. Thymus AP2 Chapter 18

45. Thymus Thymosin Target tissue: Immune Tissues • Response: • Role in development and maturation of the immune system

46. XI. Hormones of the GI-tract There are several & they relate to digestive fxns by influencing the activity of the stomach, intestine, liver, & pancreas AP2 Chapter 18

47. XII. Hormone like substances AP2 Chapter 18

48. XII. Hormone like Substances • Autocrine chemical signals are released by cells the influence the same cell type which released them. • Paracrine chemical signals are released from 1 cell type, diffuse short distance, & influence the activity of another cell type near by. • Not secreted from discrete endocrine glands • Have local FX rather than systemic FX • Have fxns that are not understood adequately to explain their role in the body AP2 Chapter 18

49. XII. Hormone like substances Autocrine Paracrine Peptide growth hormones • # of hormone like substances listed are minimal there are actually tons • Chemical communication among cells in the body is complex, well developed, & necessary for maintenance of homeostasis • Investigations increase knowledge of body fxns that can be used to develop techniques for treatment of pathologic conditions

50. XIII. FX of aging on Endocrine System • Gradual decrease in secretion rate of most, but not all, hormones • Some decreases are 2ndary to gradual decreases in physical activity • GH • Decreases w/ age but it is most drastic in people who do not exercise • Melatonin • Decreases and may help to explain the changes seen in sleeping pattern w/age AP2 Chapter 18