Endocrine Glands; Secretion&Action Of Harmones

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Endocrine Glands; Secretion&Action Of Harmones

  1. 1. Chapter 11 Endocrine Glands: Secretion and Action of Hormones www.freelivedoctor.com
  2. 2. Endocrine Glands and Hormones <ul><li>Secrete biologically active molecules into the blood. </li></ul><ul><ul><li>Lack ducts. </li></ul></ul><ul><li>Carry hormones to target cells that contain specific receptor proteins for that hormone. </li></ul><ul><li>Target cells can respond in a specific fashion. </li></ul>www.freelivedoctor.com
  3. 3. Endocrine Glands and Hormones (continued) <ul><li>Neurohormone: </li></ul><ul><ul><li>Specialized neurons that secrete chemicals into the blood rather than synaptic cleft. </li></ul></ul><ul><ul><ul><li>Chemical secreted is called neurohormone. </li></ul></ul></ul><ul><li>Hormones: </li></ul><ul><ul><li>Affect metabolism of target organs. </li></ul></ul><ul><ul><ul><li>Help regulate total body metabolism, growth, and reproduction. </li></ul></ul></ul>www.freelivedoctor.com
  4. 4. Chemical Classification of Hormones <ul><li>Amines: </li></ul><ul><ul><li>Hormones derived from tyrosine and tryptophan. </li></ul></ul><ul><ul><ul><li>NE, Epi, T 4 . </li></ul></ul></ul><ul><li>Polypeptides and proteins: </li></ul><ul><ul><li>Polypeptides: </li></ul></ul><ul><ul><ul><li>Chains of < 100 amino acids in length. </li></ul></ul></ul><ul><ul><ul><ul><li>ADH. </li></ul></ul></ul></ul><ul><ul><li>Protein hormones: </li></ul></ul><ul><ul><ul><li>Polypeptide chains with > 100 amino acids. </li></ul></ul></ul><ul><ul><ul><ul><li>Growth hormone. </li></ul></ul></ul></ul>www.freelivedoctor.com
  5. 5. Chemical Classification of Hormones (continued) <ul><li>Lipids derived from cholesterol. </li></ul><ul><ul><li>Are lipophilic hormones. </li></ul></ul><ul><ul><ul><li>Testosterone. </li></ul></ul></ul><ul><ul><ul><li>Estradiol. </li></ul></ul></ul><ul><ul><ul><li>Cortisol. </li></ul></ul></ul><ul><ul><ul><li>Progesterone. </li></ul></ul></ul>www.freelivedoctor.com
  6. 6. Chemical Classification of Hormones (continued) www.freelivedoctor.com
  7. 7. Chemical Classification of Hormones (continued) <ul><li>Glycoproteins: </li></ul><ul><ul><li>Long polypeptides (>100) bound to 1 or more carbohydrate (CHO) groups. </li></ul></ul><ul><ul><ul><li>FSH and LH. </li></ul></ul></ul><ul><li>Hormones can also be divided into: </li></ul><ul><ul><li>Polar: </li></ul></ul><ul><ul><ul><li>H 2 0 soluble. </li></ul></ul></ul><ul><ul><li>Nonpolar (lipophilic): </li></ul></ul><ul><ul><ul><li>H 2 0 insoluble. </li></ul></ul></ul><ul><ul><ul><ul><li>Can gain entry into target cells. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Steroid hormones and T 4 . </li></ul></ul></ul></ul><ul><ul><li>Pineal gland secretes melatonin: </li></ul></ul><ul><ul><ul><li>Has properties of both H 2 0 soluble and lipophilic hormones. </li></ul></ul></ul>www.freelivedoctor.com
  8. 8. Prohormones and Prehormones <ul><li>Prohormone: </li></ul><ul><ul><li>Precursor is a longer chained polypeptide that is cut and spliced together to make the hormone. </li></ul></ul><ul><ul><ul><li>Proinsulin. </li></ul></ul></ul><ul><li>Preprohormone: </li></ul><ul><ul><li>Prohormone derived from larger precursor molecule. </li></ul></ul><ul><ul><ul><li>Preproinsulin. </li></ul></ul></ul><ul><li>Prehormone: </li></ul><ul><ul><li>Molecules secreted by endocrine glands that are inactive until changed into hormones by target cells. </li></ul></ul><ul><ul><ul><li>T 4 converted to T 3 . </li></ul></ul></ul>www.freelivedoctor.com
  9. 9. Common Aspects of Neural and Endocrine Regulation <ul><li>APs are chemical events produced by diffusion of ions through neuron plasma membrane. </li></ul><ul><li>Action of some hormones are accompanied by ion diffusion and electrical changes in the target cell. </li></ul><ul><ul><li>Nerve axon boutons release NTs. </li></ul></ul><ul><ul><li>Some chemicals are secreted as hormones, and also are NTs. </li></ul></ul><ul><li>In order for either a NT or hormone to function in physiological regulation: </li></ul><ul><ul><li>Target cell must have specific receptor proteins. </li></ul></ul><ul><ul><li>Combination of the regulatory molecule with its receptor proteins must cause a specific sequence of changes. </li></ul></ul><ul><ul><li>There must be a mechanism to quickly turn off the action of a regulator. </li></ul></ul>www.freelivedoctor.com
  10. 10. <ul><li>Synergistic: </li></ul><ul><ul><li>Two hormones work together to produce a result. </li></ul></ul><ul><ul><li>Additive: </li></ul></ul><ul><ul><ul><li>Each hormone separately produces response, together at same concentrations stimulate even greater effect. </li></ul></ul></ul><ul><ul><ul><ul><li>NE and Epi. </li></ul></ul></ul></ul><ul><ul><li>Complementary: </li></ul></ul><ul><ul><ul><li>Each hormone stimulates different step in the process. </li></ul></ul></ul><ul><ul><ul><ul><li>FSH and testosterone. </li></ul></ul></ul></ul>Hormonal Interactions www.freelivedoctor.com
  11. 11. Hormonal Interactions (continued) <ul><ul><li>Permissive effects: </li></ul></ul><ul><ul><ul><li>Hormone enhances the responsiveness of a target organ to second hormone. </li></ul></ul></ul><ul><ul><ul><ul><li>Increases the activity of a second hormone. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Prior exposure of uterus to estrogen induces formation of receptors for progesterone. </li></ul></ul></ul></ul></ul><ul><ul><li>Antagonistic effects: </li></ul></ul><ul><ul><ul><li>Action of one hormone antagonizes the effects of another. </li></ul></ul></ul><ul><ul><ul><ul><li>Insulin and glucagon. </li></ul></ul></ul></ul>www.freelivedoctor.com
  12. 12. Effects of [Hormone] on Tissue Response <ul><li>[Hormone] in blood reflects the rate of secretion. </li></ul><ul><li>Half-life: </li></ul><ul><ul><li>Time required for the blood [hormone] to be reduced to ½ reference level. </li></ul></ul><ul><ul><ul><li>Minutes to days. </li></ul></ul></ul><ul><li>Normal tissue responses are produced only when [hormone] are present within physiological range. </li></ul><ul><li>Varying [hormone] within normal, physiological range can affect the responsiveness of target cells. </li></ul>www.freelivedoctor.com
  13. 13. Effects of [Hormone] on Tissue Response (continued) <ul><li>Priming effect (upregulation): </li></ul><ul><ul><li>Increase number of receptors formed on target cells in response to particular hormone. </li></ul></ul><ul><ul><li>Greater response by the target cell. </li></ul></ul><ul><li>Desensitization (downregulation): </li></ul><ul><ul><li>Prolonged exposure to high [polypeptide hormone]. </li></ul></ul><ul><ul><ul><li>Subsequent exposure to the same [hormone] produces less response. </li></ul></ul></ul><ul><ul><ul><ul><li>Decrease in number of receptors on target cells. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Insulin in adipose cells. </li></ul></ul></ul></ul></ul><ul><ul><li>Pulsatile secretion may prevent downregulation. </li></ul></ul>www.freelivedoctor.com
  14. 14. Mechanisms of Hormone Action <ul><li>Hormones of same chemical class have similar mechanisms of action. </li></ul><ul><ul><li>Similarities include: </li></ul></ul><ul><ul><ul><li>Location of cellular receptor proteins depends on the chemical nature of the hormone. </li></ul></ul></ul><ul><ul><ul><li>Events that occur in the target cells. </li></ul></ul></ul><ul><li>To respond to a hormone: </li></ul><ul><ul><li>Target cell must have specific receptors for that hormone (specificity). </li></ul></ul><ul><ul><ul><li>Hormones exhibit: </li></ul></ul></ul><ul><ul><ul><ul><li>Affinity (bind to receptors with high bond strength). </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Saturation (low capacity of receptors). </li></ul></ul></ul></ul>www.freelivedoctor.com
  15. 15. Hormones That Bind to Nuclear Receptor Proteins <ul><li>Lipophilic steroid and thyroid hormones are attached to plasma carrier proteins. </li></ul><ul><ul><li>Hormones dissociate from carrier proteins to pass through lipid component of the target plasma membrane. </li></ul></ul><ul><li>Receptors for the lipophilic hormones are known as nuclear hormone receptors. </li></ul>www.freelivedoctor.com
  16. 16. Nuclear Hormone Receptors <ul><li>Steroid receptors are located in cytoplasm and in the nucleus. </li></ul><ul><li>Function within cell to activate genetic transcription. </li></ul><ul><ul><li>Messenger RNA directs synthesis of specific enzyme proteins that change metabolism. </li></ul></ul><ul><li>Each nuclear hormone receptor has 2 regions: </li></ul><ul><ul><li>A ligand (hormone)-binding domain. </li></ul></ul><ul><ul><li>DNA-binding domain. </li></ul></ul><ul><li>Receptor must be activated by binding to hormone before binding to specific region of DNA called HRE (hormone responsive element). </li></ul><ul><ul><li>Located adjacent to gene that will be transcribed. </li></ul></ul>www.freelivedoctor.com
  17. 17. Mechanisms of Steroid Hormone Action <ul><li>Cytoplasmic receptor binds to steroid hormone. </li></ul><ul><li>Translocates to nucleus. </li></ul><ul><li>DNA-binding domain binds to specific HRE of the DNA. </li></ul><ul><li>Dimerization occurs. </li></ul><ul><ul><li>Process of 2 receptor units coming together at the 2 half-sites. </li></ul></ul><ul><li>Stimulates transcription of particular genes. </li></ul>www.freelivedoctor.com
  18. 18. Mechanism of Thyroid Hormone Action <ul><li>T 4 passes into cytoplasm and is converted to T 3 . </li></ul><ul><li>Receptor proteins located in nucleus. </li></ul><ul><ul><li>T 3 binds to ligand-binding domain. </li></ul></ul><ul><ul><li>Other half-site is vitamin A derivative (9-cis-retinoic) acid. </li></ul></ul><ul><ul><ul><li>DNA-binding domain can then bind to the half-site of the HRE. </li></ul></ul></ul><ul><ul><li>Two partners can bind to the DNA to activate HRE. </li></ul></ul><ul><ul><ul><li>Stimulate transcription of genes. </li></ul></ul></ul>www.freelivedoctor.com
  19. 19. Hormones That Use 2 nd Messengers <ul><li>Hormones cannot pass through plasma membrane use 2 nd messengers. </li></ul><ul><ul><li>Catecholamine, polypeptide, and glycoprotein hormones bind to receptor proteins on the target plasma membrane. </li></ul></ul><ul><li>Actions are mediated by 2 nd messengers (signal-transduction mechanisms). </li></ul><ul><ul><li>Extracellular hormones are transduced into intracellular 2 nd messengers. </li></ul></ul>www.freelivedoctor.com
  20. 20. <ul><li>Polypeptide or glycoprotein hormone binds to receptor protein causing dissociation of a subunit of G-protein. </li></ul><ul><li>G-protein subunit binds to and activates adenylate cyclase. </li></ul><ul><li>ATP cAMP + PP i </li></ul><ul><li>cAMP attaches to inhibitory subunit of protein kinase. </li></ul><ul><li>Inhibitory subunit dissociates and activates protein kinase. </li></ul>Adenylate Cyclase-cAMP www.freelivedoctor.com
  21. 21. Adenylate Cyclase-cAMP (continued) <ul><li>Phosphorylates enzymes within the cell to produce hormone’s effects. </li></ul><ul><li>Modulates activity of enzymes present in the cell. </li></ul><ul><li>Alters metabolism of the cell. </li></ul><ul><li>cAMP inactivated by phosphodiesterase. </li></ul><ul><ul><li>Hydrolyzes cAMP to inactive fragments. </li></ul></ul>www.freelivedoctor.com
  22. 22. <ul><li>Binding of Epi to  -adrenergic receptor in plasma membrane activates a G-protein intermediate, phospholipase C. </li></ul><ul><ul><li>Phospholipase C splits phospholipid into IP 3 and DAG. </li></ul></ul><ul><ul><ul><li>Both derivatives serve as 2 nd messengers. </li></ul></ul></ul><ul><li>IP 3 diffuses through cytoplasm to ER. </li></ul><ul><ul><li>Binding of IP 3 to receptor protein in ER causes Ca 2+ channels to open. </li></ul></ul>Phospholipase-C-Ca 2+ www.freelivedoctor.com
  23. 23. Phospholipase-C-Ca 2+ (continued) <ul><li>Ca 2+ diffuses into the cytoplasm. </li></ul><ul><ul><li>Ca 2+ binds to calmodulin. </li></ul></ul><ul><li>Calmodulin activates specific protein kinase enzymes. </li></ul><ul><ul><li>Alters the metabolism of the cell, producing the hormone’s effects. </li></ul></ul>www.freelivedoctor.com
  24. 24. Epi Can Act Through Two 2 nd Messenger Systems www.freelivedoctor.com
  25. 25. Tyrosine Kinase <ul><li>Insulin receptor consists of 2 units that dimerize when they bind with insulin. </li></ul><ul><ul><li>Insulin binds to ligand–binding site on plasma membrane, activating enzymatic site in the cytoplasm. </li></ul></ul><ul><li>Autophosphorylation occurs, increasing tyrosine kinase activity. </li></ul><ul><li>Activates signaling molecules. </li></ul><ul><ul><li>Stimulate glycogen, fat and protein synthesis. </li></ul></ul><ul><ul><li>Stimulate insertion of GLUT-4 carrier proteins. </li></ul></ul>www.freelivedoctor.com
  26. 26. Tyrosine Kinase (continued) www.freelivedoctor.com
  27. 27. Pituitary Gland <ul><li>Pituitary gland is located in the diencephalon. </li></ul><ul><li>Structurally and functionally divided into: </li></ul><ul><ul><li>Anterior lobe. </li></ul></ul><ul><ul><li>Posterior lobe. </li></ul></ul>www.freelivedoctor.com
  28. 28. <ul><li>Anterior pituitary: </li></ul><ul><ul><li>Master gland (adenohypophysis). </li></ul></ul><ul><ul><li>Derived from a pouch of epithelial tissue that migrates upward from the mouth. </li></ul></ul><ul><ul><ul><li>Consists of 2 parts: </li></ul></ul></ul><ul><ul><ul><ul><li>Pars distalis: anterior pituitary. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Pars tuberalis: thin extension in contact with the infundibulum . </li></ul></ul></ul></ul><ul><li>Posterior pituitary(neurohypophysis): </li></ul><ul><ul><li>Formed by downgrowth of the brain during fetal development. </li></ul></ul><ul><ul><li>Is in contact with the infundibulum. </li></ul></ul><ul><ul><ul><li>Nerve fibers extend through the infundibulum. </li></ul></ul></ul>Pituitary Gland (continued) www.freelivedoctor.com
  29. 29. Pituitary Hormones <ul><li>Anterior Pituitary: </li></ul><ul><ul><li>Trophic effects: </li></ul></ul><ul><ul><ul><li>High blood [hormone] causes target organ to hypertrophy. </li></ul></ul></ul><ul><ul><ul><li>Low blood [hormone] causes target organ to atrophy. </li></ul></ul></ul>www.freelivedoctor.com
  30. 30. Pituitary Hormones (continued) <ul><li>Posterior pituitary: </li></ul><ul><ul><li>Stores and releases 2 hormones that are produced in the hypothalamus: </li></ul></ul><ul><ul><ul><li>Antidiuretic hormone (ADH/vasopressin): </li></ul></ul></ul><ul><ul><ul><ul><li>Promotes the retention of H 2 0 by the kidneys. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Less H 2 0 is excreted in the urine. </li></ul></ul></ul></ul></ul><ul><ul><ul><li>Oxytocin: </li></ul></ul></ul><ul><ul><ul><ul><li>Stimulates contractions of the uterus during parturition. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Stimulates contractions of the mammary gland alveoli. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Milk-ejection reflex. </li></ul></ul></ul></ul></ul>www.freelivedoctor.com
  31. 31. Hypothalamic Control of Posterior Pituitary <ul><li>Hypothalamus neuron cell bodies produce: </li></ul><ul><ul><li>ADH: supraoptic nuclei. </li></ul></ul><ul><ul><li>Oxytocin: paraventricular nuclei. </li></ul></ul><ul><li>Transported along the hypothalamo-hypophyseal tract. </li></ul><ul><li>Stored in posterior pituitary. </li></ul><ul><li>Release controlled by neuroendocrine reflexes. </li></ul>www.freelivedoctor.com
  32. 32. Hypothalamic Control of the Anterior Pituitary <ul><li>Hormonal control rather than neural. </li></ul><ul><li>Hypothalamus neurons synthesize releasing and inhibiting hormones. </li></ul><ul><li>Hormones are transported to axon endings of median eminence. </li></ul><ul><li>Hormones secreted into the hypothalamo-hypophyseal portal system regulate the secretions of the anterior pituitary </li></ul>www.freelivedoctor.com
  33. 33. <ul><li>Anterior pituitary and hypothalamic secretions are controlled by the target organs they regulate. </li></ul><ul><ul><li>Secretions are controlled by negative feedback inhibition by target gland hormones. </li></ul></ul><ul><li>Negative feedback at 2 levels: </li></ul><ul><ul><li>The target gland hormone can act on the hypothalamus and inhibit secretion of releasing hormones. </li></ul></ul><ul><ul><li>The target gland hormone can act on the anterior pituitary and inhibit response to the releasing hormone. </li></ul></ul>Feedback Control of the Anterior Pituitary www.freelivedoctor.com
  34. 34. Feedback Control of the Anterior Pituitary (continued) <ul><li>Short feedback loop: </li></ul><ul><ul><li>Retrograde transport of blood from anterior pituitary to the hypothalamus. </li></ul></ul><ul><ul><ul><li>Hormone released by anterior pituitary inhibits secretion of releasing hormone. </li></ul></ul></ul><ul><li>Positive feedback effect: </li></ul><ul><ul><li>During the menstrual cycle, estrogen stimulates “LH surge.” </li></ul></ul>www.freelivedoctor.com
  35. 35. Higher Brain Function and Pituitary Secretion <ul><li>Axis: </li></ul><ul><ul><li>Relationship between anterior pituitary and a particular target gland. </li></ul></ul><ul><ul><ul><li>Pituitary-gonad axis. </li></ul></ul></ul><ul><li>Hypothalamus receives input from higher brain centers. </li></ul><ul><ul><li>Psychological stress affects: </li></ul></ul><ul><ul><ul><li>Circadian rhythms. </li></ul></ul></ul><ul><ul><ul><li>Menstrual cycle. </li></ul></ul></ul>www.freelivedoctor.com
  36. 36. Adrenal Glands <ul><li>Paired organs that cap the kidneys. </li></ul><ul><li>Each gland consists of an outer cortex and inner medulla. </li></ul><ul><li>Adrenal medulla: </li></ul><ul><ul><li>Derived from embryonic neural crest ectoderm (same tissue that produces the sympathetic ganglia). </li></ul></ul><ul><ul><li>Synthesizes and secretes: </li></ul></ul><ul><ul><ul><li>Catecholamines (mainly Epi but some NE). </li></ul></ul></ul>www.freelivedoctor.com
  37. 37. Adrenal Glands (continued) <ul><li>Adrenal cortex: </li></ul><ul><ul><li>Does not receive neural innervation. </li></ul></ul><ul><ul><li>Must be stimulated hormonally (ACTH). </li></ul></ul><ul><li>Consists of 3 zones: </li></ul><ul><ul><li>Zona glomerulosa. </li></ul></ul><ul><ul><li>Zona fasciculata. </li></ul></ul><ul><ul><li>Zona reticularis. </li></ul></ul><ul><li>Secretes corticosteroids. </li></ul>www.freelivedoctor.com
  38. 38. Functions of the Adrenal Cortex <ul><li>Zona glomerulosa: </li></ul><ul><ul><li>Mineralcorticoids (aldosterone): </li></ul></ul><ul><ul><ul><li>Stimulate kidneys to reabsorb Na + and secrete K + . </li></ul></ul></ul><ul><li>Zona fasciculata: </li></ul><ul><ul><li>Glucocorticoids (cortisol): </li></ul></ul><ul><ul><ul><li>Inhibit glucose utilization and stimulate gluconeogenesis. </li></ul></ul></ul><ul><li>Zona reticularis (DHEA): </li></ul><ul><ul><li>Sex steroids: </li></ul></ul><ul><ul><ul><li>Supplement sex steroids. </li></ul></ul></ul>www.freelivedoctor.com
  39. 39. Functions of the Adrenal Cortex (continued) www.freelivedoctor.com
  40. 40. Functions of the Adrenal Medulla <ul><li>Innervated by preganglionic sympathetic axons. </li></ul><ul><ul><li>Increase respiratory rate. </li></ul></ul><ul><ul><li>Increase HR and cardiac output. </li></ul></ul><ul><ul><li>Vasoconstrict blood vessels, thus increasing venous return. </li></ul></ul><ul><ul><li>Stimulate glycogenolysis. </li></ul></ul><ul><ul><li>Stimulate lipolysis. </li></ul></ul>www.freelivedoctor.com
  41. 41. Stress and the Adrenal Gland <ul><li>Non-specific response to stress produces the general adaptation syndrome (GAS). </li></ul><ul><li>Alarm phase: </li></ul><ul><ul><li>Adrenal glands activated. </li></ul></ul><ul><li>Stage of resistance: </li></ul><ul><ul><li>Stage of readjustment. </li></ul></ul><ul><li>Stage of exhaustion: </li></ul><ul><ul><li>Sickness and/or death if readjustment is not complete. </li></ul></ul>www.freelivedoctor.com
  42. 42. Thyroid Hormones <ul><li>Thyroid gland is located just below the larynx. </li></ul><ul><li>Thyroid is the largest of the pure endocrine glands. </li></ul><ul><li>Follicular cells secrete thyroxine. </li></ul><ul><li>Parafollicular cells secrete calcitonin. </li></ul>www.freelivedoctor.com
  43. 43. Production of Thyroid Hormones <ul><li>Iodide (I - ) actively transported into the follicle and secreted into the colloid. </li></ul><ul><li>Oxidized to iodine (I o ). </li></ul><ul><li>Iodine attached to tyrosine within thyroglobulin chain. </li></ul><ul><ul><li>Attachment of 1 iodine produces monoiodotyrosine (MIT). </li></ul></ul><ul><ul><li>Attachment of 2 iodines produces diiodotyrosine (DIT). </li></ul></ul><ul><li>MIT and DIT or 2 DIT molecules coupled together. </li></ul>www.freelivedoctor.com
  44. 44. Production of Thyroid Hormones (continued) <ul><li>T 3 and T 4 produced. </li></ul><ul><li>TSH stimulates pinocytosis into the follicular cell. </li></ul><ul><ul><li>Enzymes hydrolyze T 3 and T 4 from thyroglobulin. </li></ul></ul><ul><li>Attached to TBG and released into blood. </li></ul>www.freelivedoctor.com
  45. 45. Production of Thyroid Hormones (continued) www.freelivedoctor.com
  46. 46. Actions of T 3 <ul><li>Stimulates protein synthesis. </li></ul><ul><li>Promotes maturation of nervous system. </li></ul><ul><li>Stimulates rate of cellular respiration by: </li></ul><ul><ul><li>Production of uncoupling proteins. </li></ul></ul><ul><ul><li>Increase active transport by Na + /K + pumps. </li></ul></ul><ul><ul><li>Lower cellular [ATP]. </li></ul></ul><ul><li>Increases metabolic heat. </li></ul><ul><li>Increases metabolic rate. </li></ul><ul><ul><li>Stimulates increased consumption of glucose, fatty acids and other molecules. </li></ul></ul>www.freelivedoctor.com
  47. 47. Diseases of the Thyroid <ul><li>Iodine-deficiency (endemic) goiter: </li></ul><ul><ul><li>Abnormal growth of the thyroid gland. </li></ul></ul><ul><ul><ul><li>In the absence of sufficient iodine, cannot produce adequate amounts of T 4 and T 3 . </li></ul></ul></ul><ul><ul><ul><ul><li>Lack of negative feedback inhibition. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Stimulates TSH, which causes abnormal growth. </li></ul></ul></ul></ul></ul>www.freelivedoctor.com
  48. 48. Diseases of the Thyroid (continued) <ul><ul><li>[Iodine-deficiency (endemic) goiter—continued] </li></ul></ul><ul><ul><li>Adult myxedema: </li></ul></ul><ul><ul><ul><li>Accumulation of mucoproteins and fluid in subcutaneous tissue. </li></ul></ul></ul><ul><ul><li>Symptoms: </li></ul></ul><ul><ul><ul><li>Decreased metabolic rate. </li></ul></ul></ul><ul><ul><ul><li>Weight gain. </li></ul></ul></ul><ul><ul><ul><li>Decreased ability to adapt to cold. </li></ul></ul></ul><ul><ul><ul><li>Lethargy. </li></ul></ul></ul><ul><li>Grave’s disease: </li></ul><ul><ul><li>Autoimmune disorder: </li></ul></ul><ul><ul><ul><li>Exerts TSH-like effects on thyroid. </li></ul></ul></ul><ul><ul><ul><ul><li>Not affected by negative feedback. </li></ul></ul></ul></ul><ul><li>Cretinism: </li></ul><ul><ul><li>Hypothyroid from end of 1 st trimester to 6 months postnatally. </li></ul></ul><ul><ul><ul><li>Severe mental retardation. </li></ul></ul></ul>www.freelivedoctor.com
  49. 49. Parathyroid Glands <ul><li>Embedded in the lateral lobes of the thyroid gland. </li></ul><ul><li>Parathyroid hormone (PTH): </li></ul><ul><ul><li>Only hormone secreted by the parathyroid glands. </li></ul></ul><ul><li>Single most important hormone in the control of blood [Ca 2+ ]. </li></ul><ul><li>Stimulated by decreased blood [Ca 2+ ]. </li></ul><ul><li>Promotes rise in blood [Ca 2+ ] by acting on bones, kidney and intestines. </li></ul>www.freelivedoctor.com
  50. 50. Pancreatic Islets (Islets of Langerhans) <ul><li>Alpha cells secrete glucagon. </li></ul><ul><ul><li>Stimulus is decrease in blood [glucose]. </li></ul></ul><ul><ul><li>Stimulates glycogenolysis and lipolysis. </li></ul></ul><ul><ul><li>Stimulates conversion of fatty acids to ketones . </li></ul></ul><ul><li>Beta cells secrete insulin. </li></ul><ul><ul><li>Stimulus is increase in blood [glucose]. </li></ul></ul><ul><ul><li>Promotes entry of glucose into cells. </li></ul></ul><ul><ul><li>Converts glucose to glycogen and fat. </li></ul></ul><ul><ul><li>Aids entry of amino acids into cells. </li></ul></ul>www.freelivedoctor.com
  51. 51. Pineal Gland <ul><li>Secretes melatonin: </li></ul><ul><ul><li>Production stimulated by the suprachiasmatic nucleus (SCN) in hypothalamus. </li></ul></ul><ul><ul><ul><li>SCN is primary center for circadian rhythms. </li></ul></ul></ul><ul><ul><ul><li>Light/dark changes required to synchronize. </li></ul></ul></ul><ul><ul><ul><li>Melatonin secretion increases with darkness and peaks in middle of night. </li></ul></ul></ul><ul><ul><li>May inhibit GnRH. </li></ul></ul><ul><ul><li>May function in the onset of puberty (controversial). </li></ul></ul>www.freelivedoctor.com
  52. 52. Pineal Gland (continued) www.freelivedoctor.com
  53. 53. Thymus <ul><li>Site of production of T cells (thymus-dependent cells), which are lymphocytes. </li></ul><ul><ul><li>Lymphocytes are involved in cell-mediated immunity. </li></ul></ul><ul><li>Secretes hormones that are believed to stimulate T cells after leave thymus. </li></ul><ul><ul><li>Thymus gland size is large in newborns and children. </li></ul></ul><ul><li>Regresses after puberty and becomes infiltrated with strands of fibrous tissue. </li></ul>www.freelivedoctor.com
  54. 54. Gonads and Placenta <ul><li>Gonads (testes and ovaries): </li></ul><ul><ul><li>Secrete sex hormones. </li></ul></ul><ul><ul><ul><li>Testosterone. </li></ul></ul></ul><ul><ul><ul><li>Estradiol 17-  . </li></ul></ul></ul><ul><ul><ul><ul><li>After menopause, produces estrone. </li></ul></ul></ul></ul><ul><ul><ul><li>Progesterone. </li></ul></ul></ul><ul><li>Placenta: </li></ul><ul><ul><li>Secretes large amounts of estriol, progesterone, hCG, hCS. </li></ul></ul>www.freelivedoctor.com
  55. 55. Autocrine and Paracrine Regulation <ul><li>Autocrine: </li></ul><ul><ul><li>Produced and act within the same tissue of an organ. </li></ul></ul><ul><ul><ul><li>All autocrine regulators control gene expression in target cells. </li></ul></ul></ul><ul><li>Paracrine: </li></ul><ul><ul><li>Produced within one tissue and regulate a different tissue of the same organ. </li></ul></ul><ul><li>Cytokines (lymphokines): </li></ul><ul><ul><li>Regulate different cells (interleukins) . </li></ul></ul><ul><li>Growth factors: </li></ul><ul><ul><li>Promote growth and cell division in any organ. </li></ul></ul><ul><li>Neutrophins: </li></ul><ul><ul><li>Guide regenerating peripheral neurons. </li></ul></ul>www.freelivedoctor.com
  56. 56. Prostaglandins <ul><li>Most diverse group of autocrine regulators. </li></ul><ul><li>Produced in almost every organ. </li></ul><ul><li>Wide variety of functions. </li></ul><ul><li>Different prostaglandins may exert antagonistic effects in some tissues. </li></ul><ul><ul><li>Immune system: </li></ul></ul><ul><ul><ul><li>Promote inflammatory process. </li></ul></ul></ul><ul><ul><li>Reproductive system: </li></ul></ul><ul><ul><ul><li>Play role in ovulation. </li></ul></ul></ul><ul><ul><li>Digestive system: </li></ul></ul><ul><ul><ul><li>Inhibit gastric secretion. </li></ul></ul></ul>www.freelivedoctor.com
  57. 57. Prostaglandins (continued) www.freelivedoctor.com
  58. 58. Prostaglandins (continued) <ul><ul><li>Respiratory system: </li></ul></ul><ul><ul><ul><li>May bronchoconstrict or bronchodilate. </li></ul></ul></ul><ul><ul><li>Circulatory system: </li></ul></ul><ul><ul><ul><li>Vasoconstrictors or vasodilators. </li></ul></ul></ul><ul><ul><li>Urinary system: </li></ul></ul><ul><ul><ul><li>Vasodilation. </li></ul></ul></ul><ul><li>Inhibitors of prostaglandin synthesis: </li></ul><ul><ul><li>Non-steroidal anti-inflammatory drugs (NSAIDS). </li></ul></ul><ul><ul><ul><li>Aspirin, indomethacin, ibuprofen: inhibit COX1. </li></ul></ul></ul><ul><ul><li>Celecoxib and rofecoxib: inhibit COX2. </li></ul></ul>www.freelivedoctor.com

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