Various Endocrine Glands of the Body

3. Various Endocrine Glands of the Body

4. Types of Hormones • Proteins, peptides and amino acid derivatives • Proteins are large molecules made of many amino acids • Peptides are smaller molecules typically made of a few amino acids • Amino acid derivatives are molecules derived from a single amino acid

5. Lipid Hormones • Steroid hormones • Derived from cholesterol • All similar in structure, but small differences confer different effects • Similarities responsible for some cross reactivity • Eicosanoids • Derived from arachadonic acid (fat)

6. The hypothalamus • Integrates information and many functions of the nervous system • The hypothalamus controls the function of the pituitary gland in two ways • It can secrete releasing hormones that act on the pituitary to stimulate secretion of stimulating hormones • It can also stimulate the release of hormones from the posterior pituitary via nervous input

7. The Pituitary • Divided into two halves • The anterior portion is comprised of epithelial cells that act primarily as a glandular structure • The posterior portion has extensive innervation and responds to nervous sytem input from the hypothalamus

8. The hypothalamus and the Pituitary

9. Table. 10.3a

10. Table. 10.3b

12. Hormones of the Pituitary • Growth hormone • Controls growth and glucose metabolism • Mediated via the somatomedins • ACTH • Acts on the adrenal gland to stimulate the release of cortisol • Gonadotropins • Leutinizing hormone- ovulation, secretion of sex hormones • Follicle stimulating hormone – development of follicles and sperm cells

13. Prolactin – stimulates breasts to develop milk • Melanocyte stimulating hormone • Causes synthesis of melanin

14. Hormones of the Posterior Pituitary • Antidiuretic hormone (aka vasopressin) • Causes the retention of fluid in the urine • Combats dehydration • Oxytocin • Causes lactation • Contractions during child birth

16. The Thyroid Gland • Secretes two hormones that regulate metabolic rate • Thyroxine (T4) – contains four iodine atoms • Triiodothyronine (T3) – contains three iiodine atoms • Insufficient iodine impairs T3 and T4 synthesis

17. The Parathyroid Gland • Primarily responsible for calcium homeostasis • Parathyroid hormone • Causes increased production of vitamin D and increased absorption of calcium in the intestine • Also causes resorption of calcium from the bones • Increased retention of calcium in the kidneys

18. Regulation of the Thyroid Gland

19. Clinical Indication Thyroid Hormones: Replacement or supplement in hypothyroidism of any cause • cretinism- mental & physical retardation in • children with chronic untreated hypothyroidism • nontoxic goiter in adults • myxedema in adults

20. Thyroid Hormones Hormones (proteins) secreted from the thyroid gland include: • Triiodothyronine (T3) • Thyroxine (T4) • and Thyrocalcitonin TSH (Thyroid Stimulating Hormone) • Is secreted from the anterior pituitary gland in response to changes in the blood levels of T3 and T4 • Triggers T3, T4 secretion from the thyroid gland

21. Thyroid Hormones • T3, T4- concerned with muscle and nerve tissue growth • stimulates protein synthesis • increases the intestinal absorption of glucose • increases glycogen synthesis • mobilizes fatty acids • decreases serum cholesterol • increases BMR (basal metabolic rate)

22. Adverse Effects Related to Overdosing Symptoms are dose and time dependent and characteristic of hyperthyroidism and increase in sympathetic tone: • Mental confusion to psychotic behavior • Increased blood pressure • Increased heart rate • Diarrhea • Weight loss • Sweating • Menstrual irregularities • Tremors • Headache • Nervousness • Anginal episodes

23. Cautions and Contraindications Thyroid hormone therapy • is contraindicated in patients with myocardial infarction • is not recommended for weight reduction in the management of obesity • should be used with caution in patients • With cardiovascular disease, diabetes, adrenal insufficiency • Who are elderly

24. Antithyroid Drugs Clinical Indication Treatment of hypersecretory conditions of the thyroid in order to: inactivate overactive tissue inhibit production of T3 and T4

25. Effects of Hypersecretion or Hyperthyroidism May be caused by tumors on the thyroid (thyrotoxic crisis), pituitary, or hypothalamus or Autoimmune disease (Grave’s Disease) • LATS (long-acting thyroid stimulating protein) not the same as TSH but same responses occur Symptoms are dose and time dependent and characteristic of hyperthyroidism especially increased sympathetic autonomic tone

26. Antithyroid Drugs Mechanism of action Accumulate within the thyroid and destroy overactive tissue or inhibit the incorporation of iodine for production of T3 and T4 • Radioactive Iodide (immediate onset) • Methimazone (requires time to see effect) • Propylthiouracil (requires time to see effect)

27. Antithyroid Drugs Special Considerations & Contraindications • Cross the placenta and affect fetal thyroiddevelopment • Abrupt discontinuation of iodide may cause thyroid storm • Iodide should be discontinued if fever, rash, soreness in gums & teeth occur • Iodide-containing drugs are contraindicated in patients with pulmonary edema • Radioactive iodide is present in the saliva and urine 24 hours after dosing

28. Calcium Homeostasis Parathyroid Hormones Calcium ions • Essential for neuromuscular and endocrine function • Serum levels strictly regulated by two polypeptide hormones • calcitonin (thyroid) • parathormone (parathyroid)

29. Calcium Homeostasis Parathormone Stimulated when serum calcium levels are low Stimulates bone resorption to mobilize calcium Increases intestinal and renal reabsorption of calcium Calcitonin Stimulated when serum calcium levels are high Inhibits bone resorption No effect on the intestine or kidney Antagonizes parathormone

30. Calcium Disorders & Treatment • HypocalcemiaParathyroid damage during surgery Treatment: calcium salts and vitamin D • Hypercalcemia Neoplasms, multiple myeloma, renal dysfunction Treatment: diuretics to increase the renal clearance of calciumcalcitonin and bisphosphonates

31. Degenerative Bone Disease & Treatment • OsteoporosisDecreased bone mass Decreased mineral deposition Increased bone resorptionTreatment: Bisphosphonates, estrogen • Paget’s DiseaseHyperactive bone metabolism Fragile bone and microfracturesTreatment: Calcitonin, bisphosphonates

32. Bisphosphonates • Alendronate • Etidronate • Pamidronate Poorly absorbed, not metabolized, excreted in urine

33. The Adrenal Glands • Adrenal medulla responsible for the hormonal fight or flight response • Adrenal medulla releases epinephrine (adrenaline) and small amounts of norepinephrine

34. Fight or Flight Hormones • Increases breakdown of glycogen to glucose in the liver • Increase heart rate • Increases cardiac output to the tissues • Increases blood pressure • Increases metabolic rate in skeletal muscle, cardiac muscle and nervous tissue

35. The Adrenal Cortex • Produces gluccocorticoids • Cortisol • Regulates blood glucose levels • Causes amino acids to be converted to glucose in the liver • Cortisol secreted in times of stress to maintain glucose and energy levels

36. Clinical Indication Glucocorticoids Replacement therapy in adrenal insufficiency (Addison’s Disease) Interrupt moderate to severe pain associated with conditions of inflammation Mineralocorticoids Replacement therapy in adrenalectomy or adrenal tumors

37. Glucocorticoids • Adrenal cortex secretes glucocorticoids • Typically referred to as steroids • Regulate the metabolism of carbohydrates and proteins • Demand for cortisol rises during stress and tissue repair (e.g. wound healing) • Produce and conserve glucose • Promote protein catabolism and gluconeogenesis • Some mineralocorticoid activity i.e., sodium retention

38. Corticosteroids Source of steroids-natural & synthetic cortisone, hydrocortisone, prednisone, methylprenisolone, triamcinolone, betamethasone, dexamethasone Vary in duration of action and potency Antiinflammatory action stabilize cell membranesprevent edema Systemic use in patients with normal adrenal function arthritis, collagen disease, rheumatic disorders, respiratory disease, spinal cord injury Topical use for skin irritation, rashes, itching

39. Corticosteroids Adverse Effects Associated with high doses and chronic use • Exaggeration of steroid symptoms of Cushing’s disease mood changes insomniaweight gain, obesity protein catabolism, muscle weakness, wastingosteoporosis decreased wound healingincreased infections fat deposition, moon facies • Steroid addiction personality changes- “steroid psychosis”psychological dependency (falacy)

40. Steroid Contraindications • Patients with systemic fungal infections • Local viral herpes infections • Topical application to the eyes or orbital area • Live virus vaccinations

41. The Pancreas

42. The pancreas produces insulin and glucagon • The primary blood glucose regulatory hormones • Insulin produced in the beta cells of the islets of Langerhans • Glucagon produced in the alpha cells

43. Insulin • The primary glucoregulatory hormone • Elevated in response to increased blood glucose or amino acids • Inhibited when blood glucose is low • Diabetes results from perturbed insulin metabolism

44. Diabetes • Type 1- insulin dependent diabetes • The individual does not produce insulin • Type II- non-insulin dependent diabetes mellitus (adult onset) • The individual does not respond appropriately to insulin

45. Clinical Indication Maintain circulating glucose levels sufficient to promote intracellular glucose transport and provide a source of energy for cells

46. Pancreatic Endocrine Function The pancreas secrets two polypeptide hormones that regulate carbohydrate metabolism and blood glucose levels • InsulinPromotes glucose movement into cells and carbohydrate storage • GlucagonIncreases glucose in the blood by stimulatingglycogen breakdown

47. Insulin & Glucagon Secretion • Insulin is secreted by beta cells in response to elevated glucose levels • Mobilizes glucose into skeletal, heart, fat cells • Promotes storage of fat and proteinGlucagon is secreted by alpha cells in response to low glucose levels • Stimulates glyocogenolysis (breakdown) • Mobilizes glucose into the circulation

48. Diabetes Mellitus (DM) Defect in beta cell function Deficiency in insulin production and secretion Type I DM is insulin dependent (juvenile diabetes)genetic predisposition Type II DM relative insulin deficiency (maturity-onset) aging, improper diet, obesity

49. Diabetes Mellitus Symptoms • Persistently high blood glucose levels • Spill over into high urine glucose (glycosuria) • Volume of water excreted (polyuria) • Dehydration and thirst • Excessive fluid intake (polydipsia) • Excessive food intake (polyphagia) • Fat breakdown produces ketosis • Neuropathy, retinal hemorrhage • Renal dysfunction • Atherosclerosis

50. Treatment of Diabetes Mellitus Correct the metabolic imbalance with diet adjustment and administration of • Insulins • Oral sulfonylureasacetohexamide, glipizide, glyburide, tolazamide, tolbutamide • Glucose absorption inhibitorsacarbose, miglitol • Antihyperglycemic drugsMetformin, troglitazone