Chapter 18:

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

4. I. Fxns of the Endocrine System • Information needed to understand 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

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 Pituitary Gland: • Secretes 9 major hormones that regulate numerous body fxns & secretory activities of other glands 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 Figure 18.1 Pg. 610 AP2 Chapter 18

9. II. Pituitary Gland & Hypothalamus • 1cm diameter, 0.5-1g, rests in sellaturcica • Divided into 2 parts: • Posterior Pituitary • Secretions from the PP are 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

10. II. Pituitary Gland & Hypothalamus Pg 611 Fig 18.3 AP • 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

11. II. Pituitary Gland & Hypothalamus • Pg 611 Figure 18.2 • Inhibiting & releasing hormones released by hypothalamus • Growth Hormone Releasing Hormone (GHRH) • Small peptide that stimulates the secretion of Growth Hormone from the AP • Growth Hormone Inhibiting Hormone/Somatostatin (GHIH) • Small peptide that inhibits the secretion of growth hormone from AP • Thyrotropin-releasing hormone (TRH) • Small peptide that stimulating the secretion of thyroid stimulating hormone from AP • Corticotropin-releasing Hormone (CRH) • Peptide that stimulates the secretion of adrenocorticotropic hormone from AP • Gonadotropin-releasing Hormone (GnRH) • Small peptide that stimulates LH and FSH release from the AP • Prolactin-releasing Hormone (PRL) • Regulate the secretion of prolactin from the AP.

12. 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

13. II. Pituitary Gland & Hypothalamus • Pg 613 • Figure 18.4 PP • 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.

14. 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

15. II. Pituitary Gland & Hypothalamus • Pg 611 Figure 18.2 Hormones of the PP • Antidiuretic Hormone/ Vasopressin (ADH) • Constricts bld vessels & raises BP thus preventing the loss of water. (prevents large output of urine) • Secretion rate D’s in response to bld osmolarity and bd volume (osmoreceptors) • Osmolarity:  as solute [ ]  • Water intake & BP can change action potential frequency • Oxytocin • Primary fxns: • ♀Stimulates uterine contraction • ♀ Responsible for milk ejection from the breast by contraction of smooth muscle around alveoli of mammary glands • ♂ = Unknown fxn • Stimulation of oxytocin release • Stretch of the uterus, mechanical stimulation of the cervix, stimulation of the breast as baby nurses (action potentials travel from receptor up the spinal cord to hypothalamus  oxytocin releasing hormone.

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 • Response: • Increased water reabsorption & less urine prod’n • Response: • Female: Increased uterine contraction and increased milk expulsion from the mammary glands

17. II. Pituitary Gland & HypothalamusAP • 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.

18. II. Pituitary Gland & HypothalamusAP-Hormones Growth Hormone (GH)/Somatotropin Stimulus that influences GH secretion: Low bld glucose + stress stimulation of GH release High bld Glucose  Inhibition of GH release Hormonal Regulation by neurohormones of the hypothalamus: Growth Factor Releasing Hormone(GFRH)  secretion Growth Factor Inhibiting Hormone (GFiH)  Inhibition • Bind to membrane bound receptors that phosphorylate intracellular proteins • Fxns: • Stimulates growth of most tissues • Major role in regulating growth thus help determine final height • Regulation of metabolism •  mvmt of aa into cells • lipolysis •  FA release from adipocytes into bld •  glucose synthesis in liver • Imp. role in reg. bld nutrient levels after meals & fasting

19. II. Pituitary Gland & HypothalamusAP-Hormones Thyroid-Stimulating Hormone/Thyrotropin (TSH) Stimulus that influences TSH secretion: Secreted in pulsatile fashion & blood levels are highest at night Very narrow homeostatic window for TSH [ ] Reg. of secretion of TSH: Hypothalamus releases Thyroid-releasing hormone (TRH) TRH binds to receptors in AP activates G-proteins  result:  TSH secretion Thyroid hormone levels in the blood. Influences both TSH & TRH secretion • G-protein receptors in the membrane of the thyroid cells respond to binding.  [cAMP]; ’s activity of phospholipase; activates opening of Ca2+ channels to  [Ca2+] in thyroid cells • Fxn: • Stimulate synthesis & secretion of thyroid hormones from thyroid

20. II. Pituitary Gland & HypothalamusAP-Hormones Adrenocorticotropic Hormone (ACTH) & related substances Several hormones derived from proopiomelanocotin & secreted by AP. (ACTH, Lipotropins, b Endorphins, & Melanocyte stimulating hormone (MSH) Increased levels of release in response to stress & exercise ACTH • Binds to membrane-bound receptor  activation of G-protein  response • Increases hormone secretion adrenal cortex  cortisol • ACTH & MSH  bind melanocytes and increase skin pigmentation. b- endorphins •  in response to stress & exercise • Same FX as opiates (analgesics) • Other proposed fxns regulation of: • Body temp, Food intake, H2O balance MSH • Binds to membrane-bound receptor on melanocytes stimulation of melanin deposition in skin • Regulation not well understood Lipotropins Bind to membrane bound receptors in adipocytes  cause fat brkdwn & release of FA’s into circulatory system

21. II. Pituitary Gland & Hypothalamus: AP-Hormones Follicle-stimulating Hormone (FSH); Luteinizing Hormone (LH); & Prolactin A.k.a. Gonadotropins Glycoprotein hormones capable of promoting growth & fxn of gonads All play a role in reproduction regulation All released from AP • LH & FSH • Bind to membrane-bound receptors that are G-proteins • Increase intracellular synthesis of cAMP • Stimulate prod of gametes • Sperm in testes • Oocytes in ovaries • Control prod of reproductive hormones • Estrogens & progesterone in ovaries • Testosterone in testes • Regulation • Hypothalamus: • Gonadotropin releasing hormone (GnRH) • Leutinizing Hormone releasing hormone (LHRH)

22. II. Pituitary Gland & Hypothalamus: AP-Hormones Follicle-stimulating Hormone (FSH); Luteinizing Hormone (LH); & Prolactin A.k.a. Gonadotropins Glycoprotein hormones capable of promoting growth & fxn of gonads All play a role in reproduction regulation All released from AP • Prolactin • Role in milk prod’n in the mammary glands of lactating females • Binds to membrane-bound receptor that is bound to kinase phosphorylates intracellular proteins: • Enhance progesterone secretion of ovary after ovulation • Males unknown • Regulation: • Hypothalamus neurohormones • Prolactin Releasing Hormone (PRH) • Prolactin-Inhibiting Hormone (PIH)

23. AP2 Chapter 18

24. 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

25. 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

26. III. Thyroid Gland AP2 Chapter 18

27. 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

28. 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

29. III. Thyroid GlandThyroid Hormones Mechanism of Action Structure: aa derivative Target Tissue: Most cells of the body Response Increased metabolic rate  rate at wh/ glucose, fat & protein are metabolized Increased Na-K pump activity Can alter # & activity of mitochondria Essential for normal process of growth & maturation • Intracellularly: diffuse thru the PM enter nuclei & bind to receptor molecules. • This receptor-hormone complex interacts with DNA to regulate gene expression • Final action can take up to 1 week before result is seen. AP2 Chapter 18

30. III. Thyroid GlandCalcitonin • Prod’d by parafollicular cells (C-cells) • Controlled by Ca2+ levels in the Bld •  Ca2+ in the blood ’s calcitonin prod’n • Target: Bone tissue • Binds to membrane bound receptors: • Decreases osteoclast activity • Lengthens life of osteoblasts • Result: • Decreased bld Ca2+ & phosphate • Increased bone deposition AP2 Chapter 18

31. 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.

32. IV. Parathyroid Glands AP2 Chapter 18

33. IV. Parathyroid Glands • 4 small units embedded in the back of the thyroid • 2 cell Types • Chief Cells • Secrete parathyroid hormone (PTH) • Oxyphils • Unknown fxn Figure 18.11 AP2 Chapter 18

34. IV. Parathyroid Glands PTH: • Structurally • Polypeptide • Target Tissues • Bone, Kidneys, Small Intestine • Response • Increased rate of breakdown of bone by osteoclasts • Increased reabsorption of Ca2+ by kidneys • Increased absorption of Ca2+ by small intestine • Increased Vit D synthesis • Increased bld Ca2+ levels Figure 18.11 AP2 Chapter 18

35. 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

36. V. Adrenal Glands AP2 Chapter 18

37. 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

38. V. Adrenal Glands Adrenal Medulla • Hormones: • Epinephrine primarily; norepinephrine • ½ life of minutes • Structure: • AA derivatives • Target Tissue: • Heart, blood vessels, liver, fat cells • Response: • Increased cardiac output • Increased bld flow to skeletal muscle & heart • Vasoconstriction of bld vessels • Visceral organs & skin • Increased release of glucose & FA in the bld • **Preparation for physical activity**

39. 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

40. 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

41. 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

42. V. Adrenal GlandsAdrenal Cortex • Zona Glomerulosa • Outer section • Mineralcorticoids (cortisol) • Structure • steroids • Target Tissue • Most tissues • Response •  protein & fat brkdwn • Increased glucose prod’n • Inhibition of the immune response & decreased inflammation • Zona Faciculata • Middle Layer • Glucocorticoids • Structure • Steroids • Target Tissue • Kidney • Response • Increase Na+ & K and H+ excretion • Enhances water reabsorption AP2 Chapter 18

43. V. Adrenal GlandsAdrenal Cortex • Zona Reticularis • Adrenal Androgens • Structure • steroids • Target Tissue • Many Tissues • Response • Minor importance in males • In females: • Development of some 2ndary sex characteristics • Axillary & pubic hair AP2 Chapter 18

44. 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

45. VI. Pancreas AP2 Chapter 18

46. 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

47. 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

48. Cell Type: a-cells • Hormone: • Glucagon • Structure: • Polypeptide VI. Pancreas • Target Tissues: Liver • Skeletal muscle • Cardiac muscle • Cartilage • Bone • Fibroblasts • Leukocytes • Mammary glands • Adipose Cells • Nervous System • Response: • No effect • Rapid increase in breakdown of glycogen into glucose (glycogenolysis)& release of glucose into the bld. • Increased formation of glucose from aa’s & to some degree from fats • Increased metabolism of FA’s resulting in increased ketones in the bld • High [ ]’s cause the breakdown of fats (lipolysis) • Probably unimportant under most conditions • Little effect

49. VI. Pancreas Cell Type: b-cells • Hormone: • Insulin • Structure: • Protein • Target Tissues: Liver • Adipose Cells • Nervous System • Skeletal muscle • Cardiac muscle • Cartilage • Bone • Fibroblasts • Leukocytes • Mammary glands • Response: • Increased glycogen synthesis • Increased Glycolysis • Little effect except to increase glucose uptake in the satiety center • Increased glucose uptake & glycogen syntheses • Increased up-take of certain aa’s • Increased: • Glucose uptake • Glycogen synthesis • Fat synthesis • FA uptake • Glycolysis

50. VI. Pancreas • Target Tissue: • Pancreas a & b Cells • Response: • Inhibition of insulin & glucagon secretion Cell Type: d-cells • Hormone: • Somatostatin • Structure: • Peptide