Linggo, Abril 21, 2013

THANK GOD WE HAVE ADH! ☺







 




   



  


 Scribble.. Scribble.. Scribble..  


TIME TO REFLECT...
              

          Have you ever thanked God for giving you a well-designed body? A body with organized systems and different substances such as hormones that are secreted by cells, glands and other organs in order to maintain the state of balance in the body or what we call “body equilibrium”? It is truly wonderful knowing that everyone is not an accident to be here on earth but we are planned before we were created. ☺






Hello there everyone! Well, honestly speaking, this is my first time to write my own blog and to tell you frankly, I am not really fond of writing. But when our Clinical Chemistry instructors requested us to do an edublog (educational blog), I have no choice but to comply. Nevertheless, I felt agitated in doing this that I want to make sure that you will get something or will learn about my topic which is all about ADH.


KNOW THE A.D.H SONG:

            Now, allow me to introduce to you one hormone that is being produced by the hypothalamus and then be released by the posterior pituitary gland in the circulation. But before that! Let's sing first! Do you know the F.U.N SONG made by Spongebob Squarepants? 

If you don't. Watch this video:



That's the F.U.N song. It just came in to my mind and I've decided to make an A.D.H song in the tune of Spongebob's F.U.N Song:

                                 A is for anti which means against
                                 D is for diuretic
                                 H is for hormone that transmit a signal from one cell to another

                                 A for accretion of water permeability
                                 D in the distal tubules
                                 H is to heightened up water reabsorption to prevent dehydration

          Have you tried singing it? Well, this is just to give you a brief overview of the function of ADH.
          Basically, ADH stands for antidiuretic hormone which is also called “Vasopressin”. So let us define it by dissecting each word. A hormone is a chemical messenger that transfers a signal from one cell to another. The prefix “anti” means against and the word “diuretic” is the term used to any substance that promotes urine production. Combining these definitions, ADH is a chemical messenger that transmits a signal from one cell to another in order to prevent the concomitant production of urine in order to conserve water inside the body.



         ADH has a major role in the in the regulation of water balance in the body. Why is there a need for us to maintain an adequate level of water in our body? One thing I’ve remembered in life since when I was a little is that “everything that is in excess is not essential” same thing also that “lacking something is not vital”. Like for example, drinking alcohols everyday, every hour and every minute can damage your health but alcohol intake in small content offers possible health benefits especially in the heart. So this simply means that in everything, we should only be in the middle line.




LET’S PLAY TUG OF WAR!




Have you ever played tug of war? I still remember the times when my childhood friends convincing me to play this game. This game is a test for strength where the battle is between two groups that is why I always make sure to tandem with those I know have enough strength and stamina to win the game. Thinking wisely, i think. But that is not my point here. Why am I telling this game to you? Have any idea? As part of its formal rules, the rope should be marked with a center line which serves to be a mark of balance. This should be in the middle. Once it has not been placed on the center, it would be an advantage for the team that is near the center line and that would be one reason for the defeat of the other team.



This is now the role of ADH; it serves as the center line. It maintains the state of balance. Because high water level in the body can cause damage to the cell due to osmosis. On the other hand, decrease water level or dehydration may accompany to increase concentration of solute such as sodium thereby leading to the condition of Hypernatremia. THAT’S WHY THANK GOD WE HAVE ADH! ☺



            In order to understand the pathophysiology ADH, this is an illustration or a simple diagram on the compensatory mechanism for ADH. Just take a look at this one:

http://www.abpischools.org.uk/res/coResourceImport/modules/homeostasis_kidneys/fullscreenflash6-1.cfm

MECHANISM OF ACTION:
 
But how does the regulation of water take place? Let’s study its mechanism of action. ADH increase the water permeability of distal tubule and collecting duct cells in the kidney in order to allow water reabsorption and excretion of more concentrated urine. ADH has specific receptors which initiates its physiologic action. These receptors are V1 and V2. V stands for vasopressin. These two receptors have different locations and functions. V2 activates adenyl cyclase which leads to the formation of cyclic adenosine monophophate (cAMP). This will be followed by a series of steps where vesicles in the cytoplasm will mingle into the apical membrane. The insertion of water channels called aquaporins into the apical membrane of distal tubule and collecting duct epithelial cells will allow water to move down their osmotic gradient and out of the nephron, increasing the amount of water re-absorbed from the filtrate back into the blood stream (Tardy, 2008).



Take a look at this video:






By the way credits to Rosiane Pinho for this video. The video shows the binding of ADH to the V2 receptor, which is coupled to G protein, which in turn activates adenylcyclase which then lead to the transformation of ATP into cAMP. The increased concentration of intracellular cAMP activates protein kinases, which phosphorylate other proteins - including aquaporin, which will be transported to the apical membrane. The aquaporin vesicles fuse with the membrane and fall into the water channels. So if we’re going to summarize this process, in the absence of ADH, there is a very low permeability to water in the apical membrane of the cells in the collecting ducts in both cortical and medullary. Conversely, cells are much more permeable to water in the presence of ADH.

           

            So there you have it! I hope you have not only learned from it but you also enjoyed. THANK YOU AND GOD BLESS YOU! ☺



Photos taken from these sites:




Video taken from this site:





REFERENCES:

  • Bishop et al. Clinical Chemistry: Techniques, Principles, Correlations, 6th edition. 2010
  • Carieson et al. Pathophysiology: functional alterations in human health. 2007.
  • ADH and control of the water balance. (2013). Retrieved April 21, 2013, from http://www.abpischools.org.uk/page/modules/homeostasis_kidneys/kidneys6.cfm
  • Tardy, F. (2008, February 18). Anti-diuretic Hormone (ADH): Basic mechanism of action. Retrieved April 21, 2013, from Welcome to The Daily Medical Online Journal: http://thedailymedical.com/2008/02/18/antidiuretic-hormone-adh-basic-mechanism-of-action.aspx

         
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