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Saturday, August 8, 2009

Endocrine System Animations

Continue reading fullpost to view animations in endocrine system


Enzyme Amplification
Hormones are very potent chemicals even at very low concentrations due to enzyme
amplification. Even the slightest amount of hormone acting on the cell surface can initiate a powerful cascading activating force for the entire cell. View the animation below



Positive and Negative Feedback
The secretion of TSH, FSH, LH and ACTH from pituitary decreases when blood levels of their target gland hormones rise. This is called negative feedback. The other type of feed back control is positive feed back. View the animation below to understand positive and negative feedback mechanisms.



Mechanism of Hormone Action:
Lipid-soluble Hormones
Lipid-soluble hormones such as steroid hormones diffuse through lipid bilayer of the plasma membrane. They bind to intracellular hormone receptors. The activated
receptor-hormone complex influences gene expression.



Mechanism of Hormone Action:
Water-soluble Hormones
Unlike lipid-soluble hormones, water-soluble hormones like protein hormones, peptide
hormones and catecholamines cannot diffuse through lipid bilayer of the plasma membrane. They bind to receptors on the target cell membrane. This causes the production of a second messenger e.g. cAMP (cyclicAdenosineMonoPhosphate) inside the cell. The cAMP then causes subsequent intracellular effects of the hormone by activating a cascade of enzymes.


Mechanism of Thyroxine Action
Thyroid hormones are derived from the amino acid tyrosine and they have iodine incorporated into their structures. There are two thyroid hormones, which have either 3 or 4 atoms of iodine per molecule; they are known respectively as T3 (tri-iodothyronine) and T4 (thyroxine). Both are synthesized within the thyroid follicles and secreted into the bloodstream when the cells are stimulated by TSH to extrude them. When the appropriate level of T3/T4 is attained in the blood, thyroid hormones switch off TSH production. This is an example of a negative feedback system.
T3, the form of thyroid hormone which contains only 3 atoms of iodine per molecule, is now considered to be the physiologically active hormone, and T4 to be a precursor of T3, which can be converted to T3 by specific enzymes within the target cells. Since T4 circulates at a concentration about a hundred-fold higher than that of T3, it can therefore be considered to be a storage form of the active hormone.



Osteoporosis
Osteoporosis literally means "porous bones. PTH increases the activity of osteoclasts. This results in resorption of calcium phosphate ions from bone into the blood. Hypersecretion of PTH results in osteoporosis.

15 comments:

  1. Thank you sir for all the efforts taken by you to help us and thank you for being a MEAN teacher.
    (M-making;E-excellence;A;
    N-necessity)and a very happy teachers day.

    ReplyDelete
  2. Thank you sir for all the efforts taken by you to help us and thank you for being a MEAN teacher.
    (M-making;E-excellence;A;
    N-necessity)and a very happy teachers day

    ReplyDelete
  3. THANK YOU SIR FOR MAKING ME CLEAR ALL MY DOUBTS AND MAKING ZOOLOGY EASY BY YOUR SLIDES THANKS A LOT

    ReplyDelete
  4. hello sir. ur blog is awsm! Asma K.(EAMCET 2k6 batch)

    ReplyDelete
  5. hi sir!
    ur blogz awsum!!!
    u simply rock!

    ReplyDelete
  6. Hello sir .dis is student friendly,clear. Thanks 4 ur slids

    ReplyDelete
  7. haha...all animations from Mcgrawhill's website...

    ReplyDelete
  8. thank you sir for ur efforts now i cleared all the doubts in action potentials

    ReplyDelete
  9. Hello sir! This blog is just awesome!!!! I hope I can ask u 4 a little more help.Sir can u please post the tables of classifications of 2nd year topics.I wish you would consider my request.

    ReplyDelete
  10. Thank you Sir . The animations are excellent

    ReplyDelete
  11. munisa tanveer sm-ac2May 18, 2010 at 2:43 PM

    itz really very awesome.... it z better than the normal class routine

    ReplyDelete
  12. munisa tanveer sm-ac2May 18, 2010 at 2:45 PM

    itz really very interesting sir. specially, d media section. it will b very helpful 2 all d students.

    ReplyDelete
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