PSL 250 L43 Principles of Endrocrinology- circadian Rhythms- calcium control

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  1. Hormones
    • Released from endocrine glands into the blood- go everywhere
    • Bind to receptors- effects on different cell receptors dependent
    • Hydrophilic hormones to membrane receptors
    • Hydrophobic hormones bind to nuclear receptors- alter protein synthesis
  2. Plasma Hormone Concentrations
    • Controlled by feedback mechanisms
    • Hydrophilic hormones can change concentration rapidly (minutes)
    • Hydrophobic hormones often partition into adipose tissue (slower)
    • this buffers changes in plasma concentration (hours) (have to get into cells and activate protein synthesis mechanism
  3. Negative feedback
    • concentrations vary minimally around a set point
    • falling concentrations stimulate releases mechanisms
    • rising concentration inhibit release mechanisms
  4. Neuroendocrine Reflexes
    neural activation can produce a rapid increase in hormone release
  5. Dinural/ Circadian Secretion
    • day-night/ around a day rhythms- on a 24 hour cycle
    • entrained by sleep/wake or light/dark cycles
    • night shift work put some pairs of hormones out of cycle- increases junk illness (common cold)
    • recent reports of increased cancer risk, possibly due to altered melatonin release
  6. endocrine disorders
    • hyposecretion or hypersecretion - often related to endocrine or feedback cell receptor malfunction
    • target cell malfunction- no response from normal hormone level
  7. cell responsiveness
    controlled by the number or hormone receptors available on target cells
  8. down regulation
    • desensitization due to chronic, elevated hormone level
    • internalization or chemical modification of receptors
    • Type II diabetes has down regulation of insulin receptors
  9. Permissiveness
    • one hormone enhances the response of a second hormone
    • thyroid hormone increases epinephrine receptor number on target cells
  10. Synergism
    • two hormones increase each others activity
    • FSH and testosterone each help the other increase sperm production
  11. Antagonism
    • one hormone reduces the effect of another hormone
    • *progesterone decreases estrogen receptor number on the uterus
  12. pineal gland
    releases melatonin to help regulate circadian rhythms
  13. biological clocks
    • controlled by the superchiasmic nucleus in the hypothalamus
    • clock proteins in the SCN regulate their own production over a day
    • clock proteins control the neural output of the SCN, which in turn controls some hormonal outputs, like the cortisol
    • external cues keep the SCN only 24hour rhythm
  14. Melatonin
    • release from pineal gland is controlled by light: M release is high in dark
    • controls light/ dark hormonal fluctuations
    • may help sleep, decrease aging and free radicals, slow aging of immune system; link with puberty questionable
  15. plasma calcium
    • 90% of phosphate stored in bone
    • 99% of calcium stored in bone as calcium phosphate
    • Ca++ 2.5mM in plasma
    • ~10^-7M in cells; regulated by PTH
  16. Parathyroid Hormone (PTH)
    • PTH increases the reabsorption of Ca++: first from bone in fluid in spaces, and then from CaPhos
    • necessary fro life- no PTH -> hypocalcium
  17. Hypocalcemia
    • low blood calcium
    • hyperactive nerve and muscle (increase Na+ entry)
    • larynx and diaphragm- no air
  18. vitamin D
    • control of Ca++ absorption
    • enhances PTH activity
  19. Osteoporosis (OP)
    • decreased estrogen linked to OP
    • PTH, vit D, Ca++ all normal
    • decrease in bone density
    • less effect when bones are thicker at menopause (decrease of estrogen)
    • weight bearing work and exercise thickens bone
    • swimming-> no pressure on bones...stress makes them thicker
Card Set:
PSL 250 L43 Principles of Endrocrinology- circadian Rhythms- calcium control
2013-12-08 20:14:34
PSL 240 L43
MSU PSL 250 L43
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