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MD 16.00 Endocrine System

MD 16.00 Endocrine System. MD 16.01 Describe the structures of the endocrine system. MD 16.02 Analyze the function of the endocrine system. Endocrine System. ENDOCRINE GLANDS Secrete hormones directly into bloodstream Ductless EXOCRINE GLANDS Secrete substances through a duct

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MD 16.00 Endocrine System

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  1. MD 16.00 Endocrine System MD 16.01 Describe the structures of the endocrine system. MD 16.02 Analyze the function of the endocrine system.

  2. Endocrine System • ENDOCRINE GLANDS • Secrete hormones directly into bloodstream • Ductless • EXOCRINE GLANDS • Secrete substances through a duct • Sweat, salivary, lacrimal and pancreas

  3. Function of the Endocrine System • To secrete hormones • Hormones are chemical messengers that coordinate and direct target cells and organs.

  4. Hormonal Control • The secretion of hormones is controlled by either • Negative feedback • Nervous control

  5. NEGATIVE FEEDBACK • Drop in hormone level triggers a chain reaction to increase secretion, for example • Blood level of the hormone falls • Brain gets message and sends out a hormone to stimulate gland • Gland produces more hormone • When blood levels of the hormone increase, the brain hormones tell the gland to stop production.

  6. NERVOUS CONTROL • In some cases, sympathetic nervous system causes direct release of hormone from gland • for example, when stress causes the adrenal medulla to secrete adrenalin.

  7. PITUITARY GLAND • Tiny structure the size of a grape • Located at the base of the brain • Connected to the hypothalamus • Divided into anterior and posterior lobes • The “Master Gland”

  8. PITUITARY GLAND

  9. Pituitary-Hypothalamus Interaction • Release of hormones from the anterior pituitary are controlled by “releasing factors” from the hypothalamus. • While hypothalamus is part of the nervous system, it produces two hormones that are stored in the posterior pituitary

  10. Anterior Pituitary Lobe • Anterior lobe of Pituitary Gland secretes 7 hormones. • Growth Hormone • Prolactin • Thyroid-stimulating Hormone • Adrenocorticotropic Hormone • Follicle-stimulating Hormone • Luteinizing Hormone • Interstitial Cell-stimulating Hormone

  11. Anterior Pituitary Lobe

  12. GROWTH HORMONE (GH) • SOMATOTROPIN • Responsible for growth and development.

  13. PROLACTIN • Develops breast tissue • Stimulates production of milk after childbirth

  14. THYROID-STIMULATING HORMONE – TSH • Stimulates growth of thyroid gland and production of thyroxine.

  15. ADRENOCORTICOTROPIC HORMONE – ACTH • Stimulates growth of adrenal cortex and secretion of adrenocorticoids

  16. FOLLICLE-STIMULATING HORMONE – FSH • Stimulates growth of graafian follicle and production of estrogen in females, sperm in males.

  17. LUTEINIZING HORMONE – LH • Stimulates ovulation and formation of corpus luteum, which produces progesterone in females

  18. INTERSTITIAL CELL-STIMULATING HORMONE – ICSH • Production of testosterone by interstitial cells of testes in male.

  19. Posterior Pituitary Lobe • Stores 2 hormones produced by the Hypothalamus. • Vasopressin • Oxytocin

  20. VASOPRESSIN • Converts to ADH (antidiuretic hormone) in the bloodstream • Acts on kidney to concentrate urine and preserve H2O in the body

  21. OXYTOCIN • Released during childbirth causing contractions of the uterus.

  22. Pituitary Gland Disorders • Hyperfunction of Pituitary • Too much growth hormone. • In preadolescent causes overgrowth of long bones which leads to excessive tallness. GIGANTISM

  23. Gigantism Twelve-year-old boy with pituitary gigantism measuring 6'5" with his mother. Note the coarse facial features and prominent jaw.

  24. Pituitary Gland Disorders • Hyperfunction of Pituitary • too much growth hormone • In adulthood causes overdevelopment of bones in face, hands and feet • Attacks cartilage – so the chin protrudes, lips nose and extremities enlarge called ACROMEGALY • Rx – drugs to inhibit growth hormone, radiation

  25. Acromegaly

  26. Pituitary Gland Disorders • Hypofunction of pituitary (too little growth hormone.) • Occurs in childhood (DWARFISM) • Small size, but body proportions and intellect are normal • Sexual immaturity • Rx – early diagnosis, injection of growth hormone

  27. Dwarfism These girls are sisters. The girl on the left lacked growth hormone. In this picture she was 18cm shorter than her sister, despite being one and a half years older.

  28. Pituitary Dwarves and “Little People” • Most “little people” do not have pituitary dwarfism. • They have ACHONDROPLASIA. • Pituitary dwarves have very short stature, but normal body proportion.

  29. Pituitary Dwarves and “Little People” • Achondroplasia is caused by a genetic defect and may be passed on to children. • Body is disproportionate. • Legs and arms are short compared to trunk. • Prominent forehead, protruding jaw, and flat depressed area between eyes. • Legs are bowed, hands are short and stumpy and feet are short, flat and broad.

  30. Achondroplasia

  31. Other Pituitary Disorders • DIABETES INSIPIDUS • Drop in amount of ADH from posterior pituitary, excessive loss of water • Symptoms • Polyuria • Polydipsia

  32. THYMUS GLAND • Endocrine gland and lymphatic organ • Located behind the sternum, above and in front of the heart • Begins to disappear at puberty • Secretes a large number of hormones • Major hormone THYMOSIN which stimulates lymph cells to produce T-lymphocytes

  33. THYMUS GLAND

  34. THYROID GLAND • Butterfly-shaped mass of tissue • On either side of larynx, over trachea • H-shaped

  35. THYROID GLAND • Main hormone – THYROXINE – is controlled by the secretion of TSH • Thyroxine controls the rate of metabolism • Also secretes CALCITONIN • Controls calcium ion concentration in the body • Prevents hypercalcemia

  36. Thyroid Gland Disorders • HYPERTHYROIDISM • Overactive thyroid gland • Too much thyroxin secreted leading to enlargement of gland • People with this disease consume large quantities of food but lose body fat and weight

  37. Thyroid Gland Disorders • HYPERTHYROIDISM • Most pronounced symptoms are enlargement of gland (GOITER) and bulging of eyeballs (EXOPHTHALMOS) • Rx – total or partial removal of thyroid gland, drugs to reduce thyroxin, radiation

  38. HYPERTHYROIDISM

  39. Thyroid Gland Disorders • HYPOTHYROIDISM • Not enough thyroxine secreted • May be due to lack of iodine (simple goiter) • Major cause of other types is inflammation of thyroid which destroys the ability of the gland to make thyroxine • Symps – dry and itchy skin, dry and brittle hair, constipation, muscle cramps at night

  40. Thyroid Gland Disorders • HYPOTHYROIDISM • MYXEDEMA ( a form of hypothyroidism) • Hypothyroidism left untreated in adults • Face gets swollen, weight increases • Rx – daily medication of thyroxine

  41. MYXEDEMA Before and after treatment

  42. Thyroid Gland Disorders • HYPOTHYROIDISM • CRETINISM • Hypothyroidism in early infancy or childhood • Lack of mental and physical growth causes mental retardation and very small stature • Rx – thyroid extract – damage cannot be undone but treatment can halt progression

  43. PARATHYROID GLANDS • Four glands, each the size of a grain of rice • Attached to posterior thyroid • Produce PARATHORMONE which helps control blood calcium level, prevents hypocalcemia

  44. PARATHYROID GLANDS

  45. Parathyroid Gland Disorders • TETANY • In hypoparathyroidism, decreased calcium levels affect function of nerves • Convulsive twitching develops, person dies of spasms in the respiratory muscles • Rx – Vitamin D, calcium and parathormone

  46. Parathyroid Gland Disorders • HYPERPARATHYROIDISM • Excessive levels of Parathormone • Causes elevated blood calcium levels which can lead to kidney stones • Calcium is drawn from bones causing deformity and weakness of the bones

  47. Blood Calcium Levels • Adequate blood calcium is necessary for proper muscle contractions (especially cardiac muscle) • Blood calcium levels are controlled by two endocrine system hormones. • Calcitonin from the thyroid gland prevents calcium concentration from getting too high. • Parathormone from the parathyroid prevents calcium concentration from getting too low.

  48. ADRENAL GLANDS • Located on top of each kidney • Adrenal gland has 2 parts: • Cortex (outer) • Medulla (inner) • Adrenal glands are controlled by ACTH from the pituitary.

  49. ADRENAL GLANDS • Adrenal cortex secretes hormones known as corticoids – (natural steroids) • They are: mineralcorticoids, glucocorticoids, and sex hormones.

  50. ADRENAL GLANDS • Mineralcorticoids • Affects the amount of sodium and potassium excreted by the kidneys. • Also involved in amount of water retained by the kidneys.

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