Chapter 15 Hormones Lesson 1 - Endocrine Glands and the effects of insulin

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Chapter 15 Hormones Lesson 1 - Endocrine Glands and the effects of insulin

  1. 1. Hormones and endocrine glands Chapter 15
  2. 2. Hormones <ul><li>Definition </li></ul><ul><li>Chemical substances produced in minute quantities by an endocrine gland that is transported in the bloodstream to target organ(s) where it exerts its effects </li></ul><ul><li>Assist nervous system in coordination (synergy) </li></ul><ul><li>Have powerful effects on the body (must balance production) </li></ul><ul><li>2 functions: </li></ul><ul><li>Exercise control over other glands/muscles </li></ul><ul><li>Control/coordinate body activities (growth & development) </li></ul>
  3. 3. 1. 2. 2 methods of testing hormonal levels in our bodies
  4. 4. Endocrine vs exocrine glands <ul><li>Exocrine glands </li></ul><ul><li>= glands that have ducts to carry away their secretions out of the body </li></ul><ul><li>Endocrine glands </li></ul><ul><li>= ductless glands </li></ul><ul><li>= does not have ducts/tubes to carry away its secretion (hormones pass directly into bloodstream for distribution around the body ) </li></ul>
  5. 5. Examples <ul><li>Endocrine </li></ul><ul><li>thyroid gland </li></ul><ul><li>(thyroxine) </li></ul>Exocrine sweat gland (sweat) Both gonads (testosterone) pancreas (pancreatic juice) Islets of Langerhans (insulin & glucagon)
  6. 6. Location of endocrine glands
  7. 7. Location of the adrenal gland
  8. 8. Control of endocrine glands <ul><li>By nervous system </li></ul><ul><li>Chemical substances </li></ul><ul><li>Hormones from other endocrine glands </li></ul>
  9. 9. Important pointers: <ul><li>Pituitary gland = “master gland”/”controller” </li></ul><ul><li>-> secretes a number of hormones </li></ul><ul><li>-> each controls particular gland activity </li></ul><ul><li>Some glands do not function until a certain age </li></ul><ul><li>-> reproductive organs (gonads) </li></ul><ul><li>Long-term vs short-term hormones </li></ul><ul><li>-> thyroxine (long-term, permanent effects) </li></ul><ul><li>-> adrenaline (short-lived effects) </li></ul>
  10. 10. Important pointers: <ul><li>Production of hormones must be adequate and balanced </li></ul><ul><li>-> excessive production of certain hormones may be harmful </li></ul><ul><li>Hormones are destroyed by the liver and excreted by the kidneys after performing their functions </li></ul>
  11. 11. Insulin
  12. 12. Islet of Langerhans (in pancreas) <ul><li>produce insulin </li></ul><ul><li>during increase in blood glucose concentration </li></ul><ul><li>Effects of insulin: [overall increase in cell glucose utilization] </li></ul><ul><li>Increased cell membrane permeability to glucose -> increasing rate of glucose uptake by cells </li></ul><ul><li>Cause increased oxidation of glucose during tissue respiration </li></ul><ul><li>Causes conversion of EXCESS glucose to glycogen for storage in liver and muscles </li></ul>
  13. 13. Effects of lack of secretion <ul><li>Blood glucose conc. rises </li></ul><ul><li>-> not utilized by cells </li></ul><ul><li>-> diabetes mellitus </li></ul><ul><li>Body weakness </li></ul><ul><li>-> no glycogen reserves </li></ul><ul><li>-> continuous loss of weight </li></ul><ul><li>Fat oxidation preferred </li></ul><ul><li>-> formation of ketones (poisonous) </li></ul><ul><li>-> excreted in urine ( ketonuria ) </li></ul><ul><li>-> death may occur </li></ul>
  14. 14. Effects of oversecretion <ul><li>Abnormal decrease in blood glucose conc. </li></ul><ul><li>Shock results </li></ul><ul><li>Coma and death ensues </li></ul>
  15. 15. Diabetes mellitus <ul><li>Body unable to control its blood glucose conc. within safe limits </li></ul><ul><li>Kidney unable to reabsorb all the glucose </li></ul><ul><li>Glucose not reabsorbed is excreted in the urine </li></ul><ul><li>2 main types: </li></ul><ul><li>Type 1 </li></ul><ul><li>Type 2 </li></ul>
  16. 16. Type 1 diabetes <ul><li>Juvenile/early-onset diabetes (occurs early in life) </li></ul><ul><li>Due to inability of pancreas to produce sufficient insulin </li></ul>
  17. 17. Type 2 diabetes <ul><li>Late-onset diabetes (occurs later in life) </li></ul><ul><li>Overweight people more prone </li></ul><ul><li>Due to failure of target cells (e.g. muscle cells) to respond to insulin </li></ul>
  18. 19. Treatment <ul><li>Measure blood glucose conc. </li></ul><ul><li>Test urine regularly </li></ul><ul><li>Watch diet carefully (not too much carbohydrate intake) </li></ul><ul><li>Type 1 : </li></ul><ul><li>Inject insulin into veins daily </li></ul><ul><li>Ensure supply of sugary foods </li></ul><ul><li>-> too low (due to too much insulin, </li></ul><ul><li>exercise too much or eat too little </li></ul><ul><li>-> coma </li></ul><ul><li>Type 2 : </li></ul><ul><li>Watch carbohydrate content in diet </li></ul><ul><li>Seldom need for insulin jabs </li></ul>

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