Biological complexity: calcium blood level controls (Introduction)

by David Turell , Thursday, June 09, 2016, 23:25 (3089 days ago) @ dhw

Another discussion of complex biologic processes. In this case calcium control:-http://www.evolutionnews.org/2016/06/how_the_body_co102899.html- "For when it comes to life, real numbers have real consequences. Clinical experience teaches that not just any Ca++ ion concentration in the blood will do. It has to be the right amount. The normal blood level for calcium is between 8 to 10 units and if it rises above or drops below this range by more than 30 percent, the result is often lethal. So how does the body maintain control of its calcium?-***-"The system the body uses to control its blood level of calcium requires calcium sensors on the parathyroid gland cells, the ability for these cells to produce PTH, properly adjusted release of PTH to the change in the calcium blood level, enzymes to limit the effect of PTH, and specific PTH receptors on the bone cells, tubule, and specialized cells of the kidneys. Without any one of these five components being present and doing what they're supposed to do, the whole system would fail and calcium control would be lost.-"But for our earliest ancestors to have survived, not only would they have needed this irreducibly complex system but, in addition, it would have had the natural survival capacity to make sure the blood level of calcium stayed within the right range. In other words, the systems the body uses must do the right thing at the right time and they must do these well enough to survive under the laws of nature. In any realistic perspective, the idea that such a wonder came about by chance and nature's laws alone must be set aside as untenable."-Comment; Note multi-organ involvement for tight control. Not by chance!!