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Endocrine System

Endocrine System. Anatomy, Physiology, Diagnostics, & Pathology. Key Terms. Diabetes insipidus Pituitary disorder, ADH deficiency Diabetes mellitus Disorder of glucose metabolism Electrolytes Ionic components of serum (Na, K, Cl, etc) Glucagon

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Endocrine System

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  1. Endocrine System Anatomy, Physiology, Diagnostics, & Pathology

  2. Key Terms • Diabetes insipidus • Pituitary disorder, ADH deficiency • Diabetes mellitus • Disorder of glucose metabolism • Electrolytes • Ionic components of serum (Na, K, Cl, etc) • Glucagon • Pancreatic hormone that increases serum glucose level

  3. Key Terms • Hormone • Hyperglycemia • Insulin • Mimetic (eg sympathomimetic) • Target organ

  4. Endocrine Anatomy • Hormones • Target organs/tissues • Hyposecretion • Hypersecretion • Organs involved: pituitary, thyroid, parathyroid, adrenal, pancreatic, & pineal glands

  5. Pituitary Gland (Hypophysis) • The “Master Gland” • Basilar area of the brain • Two lobes: • Anterior • Andenohypophysis • Secretes 6 major hormones • Posterior • Neurohypophysis • Stores & releases 2 hormones from hypothalamus

  6. Pituitary Hormones • Anterior pituitary hormones and target organs • GH (bones, muscles) • ACTH (adrenal gland) • TSH (thyroid gland) • FSH, LH (testes, ovaries) • Prolactin (mammary glands)

  7. Pituitary Hormones: Diseases & Conditions • ACTH • Hyposecretion: Addison’s Disease • Hypersecretion: Cushing’s Disease • GH • Hyposecretion: pituitary dwarfism • Hypersecretion: gigantism, acromegaly • TSH • Hyposecretion: cretinism • Hypersecretion: Graves Disease

  8. Pituitary Hormones: Diseases & Conditions • FSH • Hyposecretion: sexual immaturity • LH • Hyposecretion: sexual immaturity • Prolactin • Hyposecretion: poor lactation in nursing mothers • Hypersecretion: galactorrhea

  9. Pituitary Hormones • Posterior pituitary hormones and end organs: • ADH (kidneys) • Hyposecretion = DI • Hypersecretion = SIADH • Oxytocin (mammary glands, uterus)

  10. Thyroid Gland • Largest endocrine gland • In anterior neck • Two lobes and isthmus • TH = thyroid hormone • T4 = thyroxine, secreted by thyroid • T3 = triiodothyronine, made at end organs

  11. Thyroid Gland • TH Functions • Major metabolic hormone • Increases O2 use and metabolic rate • Increases use of CHO, proteins, fats • Hyposecretion/ hypothyroidism • Slower metabolic rate, myxedema • Hypersecretion/ hyperthyroidism • Faster metabolic rate, Graves Disease

  12. Thyroid Hormones: continued • Calcitonin • Works with PTH to regulate serum Ca • Lowers serum Ca • Relatively weak agent • Greatest effect during childhood

  13. Parathyroid Glands • Four small separate glands (or more) • Posterior surface of thyroid • PTH = parathyroid hormone • Target organs: bone, kidney, intestines • Causes bone to release Ca, PO4 • Increases intestinal absorption of Ca, PO4 • Increases renal reabsorption of Ca, PO4

  14. Parathyroid Glands: Diseases • Hyposecretion • Tetany (low Ca) • Hypersecretion • Osteitis fibrosa cystica due to excessive bone resorption

  15. Adrenal Glands (Suprarenal Glands) • Paired organs on superior poles of kidneys • Two sections • Outer cortex (most of the gland) • Inner medulla

  16. Adrenal Cortex: Hormones • Mineralocorticoids • Aldosterone • Water & electrolyte metabolism • Glucocorticoids • Cortisol • Glucose, fat, protein, carbohydrate metabolism • Sex Hormones • Androgens, estrogens, protestins • Maintain secondary sex characteristics

  17. Adrenal Medulla: Hormones • Epinephrine • Greater amount • Adrenaline • Maintains serum glucose, BP, & CO, bronchodilation • Norepinephrine • Noradrenaline • vasoconstrictor

  18. Adrenal Diseases & Conditions • Cortical • Glucocorticoids • Hyposecretion: Addison Disease • Hypersecretion: Cushing Disease • Mineralocorticoids • Hyposecretion: Addison Disease • Hypersecretion: aldosteronism • Sex Hormones • Hypersecretion: virilism or feminization

  19. Adrenal Diseases & Conditions • Medullary • NE and epinephrine • Hypersecretion: hypertension, hyperadrenergic state (excessive/chronic fight or flight state)

  20. Pancreas (Islets of Langerhans) • Upper abdominal organ • Exocrine function • GI/digestive function, fat digestion • Endocrine function • Islets of Langerhans, two types of cells & hormones • Alpha cells • Glucagon production • Beta cells • Insulin production

  21. Pancreatic Endocrine Hormones • Glucagon • Respond to serum hypoglycemia • Increase serum glucose levels • Glycogenolysis in liver • Insulin • Responds to serum hyperglycemia • Lowers serum glucose levels • Enhances peripheral use of glucose • Increases glycogen storage in liver

  22. Pancreatic Endocrine Diseases • Glucagon • Hyposecretion • Persistent hypoglycemia • Insulin • Hyposecretion • Diabetes mellitus • Hypersecretion • hyperinsulinism

  23. Pineal Gland • Intracerebral gland • Posterior part of ventricle III in brain • Secretes melatonin • May block ovarian function e.g. ovulation and delay of puberty

  24. Combining Forms: Endocrine • Adreno- or adrenalo- • Calco- = calcium • Crino- = secrete • Gluco-, glyco-, glycoso- = glucose • Homeo- = same, alike • Kali- = potassium • Pancreatico-

  25. Combining Forms • Parathyroido- • Thyro- or thyroido- • Toxico- = toxin, poison

  26. Suffixes & Prefixes • -crine • -dipsia = thirst • -gen = forming • -uria = urine • Eu- = normal • Exo- = outside • Poly- = many or much

  27. Diseases and Conditions • Pituitary disorders • Hypo- or hypersecretion of various hormones lead to different disease states • GH secretion abnormalities: body size abnormalities • ADH abnormalities: imbalances in blood and serum composition and electrolytes • Etc.

  28. Pathology: Thyroid • Thyroid disorders: occur throughout life • Hypothyroidism in infancy: cretinism • Hypothyroidism in adulthood: • Extreme form is myxedema • Edema, low T3 & T4 levels, weight gain • Sluggishness, mental retardation/coma • Common in middle-aged and older females

  29. Pathology: Thyroid • Hyperthyroidism • Graves Disease • More common, higher metabolic rate • Exophthalmos, wt. Loss, sweating, muscle weakness, thyroid enlargement (goiter) • Toxic goiter • Often due to excessive TSH from pituitary • Treatments: surgical resection, radioactive iodine, drug therapy to inhibit TSH secretion

  30. Pathology: Parathyroid • Hypoparathyroidism • Deficiency of PTH from various causes • Chronically high Ca levels in serum • Surgical removal of glands, etc • Causes low blood calcium levels • Hypocalcemia can cause tetany • Increasing nerve impulse conduction • Spasm of muscles in hands and feet

  31. Pathology: Parathyroid • Hyperparathyroidism • Overproduction of PTH • Common cause: benign adenoma • Causes bone demineralization • Osteitis fibrosa cystica, osteoporosis • Causes high serum Ca levels • May deposit calcium in kidneys • nephrolithiasis • Von Recklinghausen Disease • Generalized disease of PTH oversecretion

  32. Pathology: Adrenal • Adrenal cortex • Addison disease • Uncommon, probably autoimmune • Deficiency of cortical hormones • Patient is unable to handle physiological stresses • Muscle weakness, anorexia, fatigue, hypoglycemia, hyponatremia, hyperkalemia, chronic dehydration • Treat with replacement hormones (steroids)

  33. Pathology: Adrenal • Adrenal cortex: • Cushing syndrome • Excessive cortisol, ACTH or both • Hyperglycemia, protein depletion eventually • Na retention, water retention, weight gain, edema • Moon-faces, buffalo hump, truncal obesity • Hypertension, hirsutism • Causes: pituitary disorder, long term steroid treatment, hypersecreting adrenal tumor

  34. Pathology: Adrenal Medulla • Pheochromocytoma • Tumor that secretes NE and epinephrine • Periodic and paroxysmal symptoms: • Sweating, hypertension, palpitations, high heart rate, muscle spasm, blurriness of vision, anxiety

  35. Pathology: Pancreas • Diabetes mellitus • Single most common endocrine disorder • Due to deficiency of insulin or inability to use insulin by peripheral tissues (insulin resistance) • General symptoms & signs: hyperglycemia, polyuria (glycosuria), polydipsia, polyphagia

  36. Diabetes: Two Types • Type 1 • Juvenile onset • Patient appears thin despite appetite • Pancreas does not make insulin • Insulin-dependent DM (IDDM) • Treatment must include insulin • Onset may appear sudden • May present with diabetic emergencies • Diabetic Ketoacidosis (DKA)

  37. Diabetes: Two Types • Type 2 • Adult onset, much more common • Often overweight • Makes some insulin (not enough or not effectively utilized by cells) • Treatment ranges from diet control, exercise, oral hypoglycemic meds, to insulin

  38. Diabetes: Complications • Risk factor for cardiovascular and cerebrovascular disease • Retinopathy/ visual changes • Renal failure • Paresthesias, especially LE • Increased risk of infections • Diabetic ketoacidosis, diabetic coma, hypoglycemia due to treatment • Risk of fetal distress & congenital malformations in pregnant diabetics

  39. Oncology: • Pancreatic: adenocarcinoma • Pain is major presenting complaint • Poor px, 2% five-year survival • Geriatric patients mostly • Associated with smoking, chemical exposure, high fat diet, heavy coffee intake

  40. Oncology • Pituitary: usually benign but locally invasive • Headache, blurry vision early • Thyroid: • Thyroid carcinoma • Often painless, firm goiter • Risk factors: prolonged TSH stimulation, familial hx, chronic goiter • May be hypo- or hyperthyroid

  41. Related Terms: • Acromegaly (mostly face & jaw) • Diuresis • Hypervolemia • Insulinoma • Obesity • Panhypopituitarism • pheochromocytoma

  42. Related Terms: • Thyroid storm • Virile • Virilism

  43. Diagnostics: • Glucose Tolerance Test (GTT) • Thyroid Scan (radioactive substance’s uptake by thyroid gland) • Radioactive Iodine uptake (RAIU) • Hemoglobin A1C: averages serum glucose level over previous 3 months • Fasting serum glucose level

  44. Treatment: Procedures • Pituitary microsurgery • Parathyroidectomy • Pinealectomy • Thryroidectomy (partial, subtotal, total)

  45. Treatment: Pharmacologic • Insulins (Humulin, Novolin, short or long acting) • Oral antidiabetics (Hypoglycemics) • Metformin, glipizide, glyburide, etc • Antithyroids • Lugol’s iodine solution, methimazole

  46. Treatment: Pharmacologic • Corticosteroids • Cortisone, hydrocortisone, prednisone • GH replacement • Somatropin or somatrem • Thyroid supplements • L-thyroxine, thyroid

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