Endocrine Notes

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    22-Jan-2015

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<ul><li> 1. Endocrine System </li> <li> 2. Endocrine Glands <ul><li>The endocrine system is made of glands and tissues that secrete hormones. </li></ul><ul><li>Endocrine glands are ductless organs, producing their messengers and secreting them directly into the bloodstream, whereas other glands (exocrine glands) produce their chemicals and excrete them into a duct (ex. digestive enzymes, sweat). </li></ul></li> <li> 3. <ul><li>Hormones are chemicals that influence metabolism of cells, the growth and development of body parts, and homeostasis. </li></ul><ul><li>Hormones can be classified as protein or steroids . </li></ul></li> <li> 4. <ul><li>Hormones (meaning set in motion) are chemical regulators produced by cells of endocrine glands in one part of the body that affect cells in other parts of the body. They can be divided into two types: </li></ul><ul><li>- target hormones affect specific cells in the body (e.g. gastrin stimulates stomach cells) - nontarget hormones have broad effects in the body (e.g. growth hormone affects the growth of long bones) </li></ul></li> <li> 5. <ul><li>There is a close association between the endocrine and nervous systems. </li></ul><ul><li>Hormone secretion is usually controlled by either negative feedback or antagonistic hormones that oppose each others actions, and results in maintenance of a bodily substance or function within normal limits. </li></ul></li> <li> 6. The Endocrine System </li> <li> 7. Chemical Signals <ul><li>A chemical signal is any substance that affects cell metabolism or behavior of the individual. </li></ul><ul><li>Chemical signals can be used between body parts, between cells, and between individual organisms ( pheromones ). </li></ul><ul><li>Underarm secretions may be slightly attractive and may be involved in synchronizing the menstrual cycles of women who live together. </li></ul></li> <li> 8. Chemical signals </li> <li> 9. Chemical signals </li> <li> 10. The Action of Hormones <ul><li>Steroid hormones enter the nucleus and combine with a receptor protein, and the hormone-receptor complex attaches to DNA and activates certain genes. </li></ul><ul><li>Transcription and translation lead to protein synthesis. </li></ul></li> <li> 11. Hormones trigger changes in their target cells when they bind to receptor proteins on or within the cells. A model of a hormone (A) bound to its protein receptor (B). Each hormone of the endocrine system has a unique molecular shape, which fits into a specific receptor protein on its target cells. </li> <li> 12. Action of a steroid hormone </li> <li> 13. <ul><li>Peptide hormones are usually received by a hormone receptor protein located in the plasma membrane. </li></ul><ul><li>Most often the reception of a peptide hormone leads to activation of an enzyme that changes ATP to cyclic AMP (cAMP). </li></ul><ul><li>cAMP, as a second messenger , then activates an enzyme cascade. </li></ul><ul><li>Calcium is also a common second messenger. </li></ul><ul><li>Hormones work in small quantities because their effect is amplified by enzymes. </li></ul></li> <li> 14. Action of a peptide hormone </li> <li> 15. <ul><li>Hormone production will be regulated in most cases by negative feedback systems. Once the desired outcome is reached, the outcome will inhibit the hormone release. </li></ul><ul><li>Hormones are also classified as: </li></ul><ul><li><ul><li>Tropic: have endocrine glands as their target </li></ul></li></ul><ul><li><ul><li>Non-tropic:dont have endocrine glands as their target </li></ul></li></ul></li> <li> 16. The Endocrine System </li> <li> 17. Hypothalamus and Pituitary Gland <ul><li>The hypothalamus regulates the internal environment through the autonomic system and also controls the secretions of the pituitary gland. </li></ul><ul><li>The pituitary has two portions: the anterior pituitary and the posterior pituitary. </li></ul></li> <li> 18. Posterior Pituitary <ul><li>The posterior pituitary stores and releases the antidiuretic hormone ( ADH ) and oxytocin produced by the hypothalamus. </li></ul><ul><li>ADH is secreted during dehydration and causes more water to be reabsorbed by the kidneys; the secretion of ADH is regulated by negative feedback. </li></ul></li> <li> 19. Posterior Pituitary ADH is released when the blood plasma concentration is high (and blood pressure is low). ADH stimulates the kidneys to absorb more water, which dilutes the blood plasma (and increases blood pressure). </li> <li> 20. Posterior Pituitary <ul><li>Oxytocin causes uterine contractions and milk release, and is controlled by positive feedback. </li></ul></li> <li> 21. Anterior Pituitary <ul><li>The hypothalamus controls the anterior pituitary by producing hypothalamic-releasing hormones and hypothalamic-inhibiting hormones . </li></ul><ul><li>The anterior pituitary produces six hormones. </li></ul><ul><li>Three of these six hormones have an effect on other endocrine glands: </li></ul><ul><li>Thyroid-stimulating hormone ( TSH ) stimulates the thyroid to produce thyroid hormones; </li></ul></li> <li> 22. <ul><li>2) adrenocorticotropic hormone ( ACTH ) stimulates the adrenal cortex to produce cortisol; </li></ul><ul><li>3) the gonadotropic hormones (FSH and LH) stimulate the gonads to produce sex cells and hormones. </li></ul><ul><li>In these three instances, the blood level of the last hormone exerts negative feedback control over the secretion of the first two hormones. </li></ul></li> <li> 23. </li> <li> 24. <ul><li>The next three anterior pituitary hormones do not effect other endocrine glands. </li></ul><ul><li>After childbirth, prolactin ( PRL ) causes mammary glands to produce milk. </li></ul><ul><li>Growth hormone ( GH ) promotes skeletal and muscular growth. </li></ul><ul><li>Melanocyte-stimulating hormone ( MSH ) causes skin color changes in fishes, amphibians, and reptiles. </li></ul></li> <li> 25. Hypothalamus and the pituitary </li> <li> 26. Effects of Growth Hormone <ul><li>The quantity of GH is greatest during childhood and adolescence; GH promotes bone and muscle growth. </li></ul><ul><li>Pituitary dwarfism results from too little GH during childhood. </li></ul><ul><li>Giants result from too much growth hormone during childhood. </li></ul><ul><li>If growth hormone is overproduced in an adult, it causes acromegaly . </li></ul></li> <li> 27. Effect of growth hormone </li> <li> 28. Acromegaly </li> <li> 29. Adrenal Glands <ul><li>Adrenal glands sit atop the kidneys and have an inner adrenal medulla and an outer adrenal cortex . </li></ul><ul><li>The hypothalamus uses ACTH-releasing hormone to control the anterior pituitarys secretion of ACTH that stimulates the adrenal cortex. </li></ul><ul><li>The hypothalamus regulates the medulla by direct nerve impulses. </li></ul></li> <li> 30. The adrenal glands release several hormones involved in the bodys response to stress. </li> <li> 31. <ul><li>The adrenal medulla secretes epinephrine and norepinephrine , which bring about responses we associate with emergency situations. </li></ul><ul><li>On a long-term basis, the adrenal cortex produces glucocorticoids similar to cortisone and mineralocorticoids to regulate salt and water balance. </li></ul><ul><li>The adrenal cortex also secretes both male and female sex hormones in both sexes. </li></ul></li> <li> 32. Adrenal glands </li> <li> 33. Glucocorticoids <ul><li>Cortisol promotes breakdown of muscle proteins to amino acids; the liver then breaks the amino acids into glucose. </li></ul><ul><li>Cortisol also promotes metabolism of fatty acids rather than carbohydrates, which spares glucose. </li></ul><ul><li>Both actions raise the blood glucose level. </li></ul><ul><li>High levels of blood glucocorticoids can suppress immune system function. </li></ul></li> <li> 34. Mineralocorticoids <ul><li>Aldosterone causes the kidneys to reabsorb sodium ions (Na + ) and excrete potassium ions (K + ). </li></ul><ul><li>When blood sodium levels and blood pressure are low, the kidneys secrete renin; the effect of the renin-angiotensin-aldosterone system is to raise blood pressure. </li></ul></li> <li> 35. Regulation of blood pressure and volume </li> <li> 36. Malfunction of the Adrenal Cortex <ul><li>Addison disease develops when the adrenal cortex hyposecetes hormones. </li></ul><ul><li>A bronzing of the skin follows low levels of cortisol, and mild infection can lead to death; aldosterone is also hyposecreted, and dehydration can result. </li></ul><ul><li>Cushing syndrome develops when the adrenal cortex hypersecretes cortisol. </li></ul><ul><li>The trunk and face become round; too much aldosterone results in fluid retention. </li></ul></li> <li> 37. Addison disease </li> <li> 38. Cushing syndrome </li> <li> 39. Pancreas <ul><li>The pancreas is between the kidneys and the duodenum and provides digestive juices and endocrine functions. </li></ul><ul><li>Pancreatic Islets of Langerhans secrete: </li></ul><ul><li>- insulin , from the beta cells, which lowers the blood glucose level </li></ul><ul><li>- insulin makes cells more permeable to glucose </li></ul><ul><li>- glucagon , from the alpha cells, which increases the blood glucose level </li></ul><ul><li>- glucagon causes the conversion of glycogen to glucose </li></ul></li> <li> 40. Pancreas </li> <li> 41. Regulation of blood glucose level </li> <li> 42. Diabetes Mellitus <ul><li>The most common illness due to hormonal imbalance is diabetes mellitus . </li></ul><ul><li>Diabetes is due to the failure of the pancreas to produce insulin or the inability of the body cells to take it up. </li></ul><ul><li>Hyperglycemia symptoms develop, and glucose appears in the urine. </li></ul><ul><li>Diabetes is diagnosed using a glucose tolerance test. </li></ul></li> <li> 43. Glucose tolerance test </li> <li> 44. <ul><li>TYPE I insulin-dependent </li></ul><ul><li>caused by lack of insulin production in pancreas, hereditary but may skip generations </li></ul><ul><li>treated with insulin injections and rigid blood monitoring </li></ul><ul><li>since insulin is a protein it would be digested if taken orally </li></ul><ul><li>must monitor both hypoglycemia (need glucagon or glucose) and hyperglycemia (need insulin) </li></ul><ul><li>in research: islet transplants, gene therapy (thought to have found gene) </li></ul></li> <li> 45. <ul><li>TYPE II- insulin-independent </li></ul><ul><li>caused by decreased insulin production, or too much glucose produced by the liver (not enough compensation by pancreas), insulin resistance </li></ul><ul><li>gestational diabetes, during pregnancy, mother develops symptoms at a greater risk for type II later in life </li></ul></li> <li> 46. <ul><li>diabetes insipidous, which has nothing to do with insulin, but ADH production in the pituitary a tumour or injury causes ADH or response to ADH, ca...</li></ul></li></ul>

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