A doctor who is a secular humanist talks about the “design” of the kidney

Well I'm very glad that Darwin's theory selected for a bladder... so I can conveniently store my urine until I find time and place to dispose of it properly. So why would selection favor the evolving of a resevoir for temporary holding and storing of urine ? Johnnyfarmer

Another issue for evolution about the kidney is how its the same for almost all creatures. Unless there was massive convergent evolution going on and coming to the same conclusions then everyones kidney is a "living fossil" or a very ancient common ancestor. And ever since the kidney has not needed much revamping. Evolution did the great kidney and its complexity right RIGHT away. Are evolutionists really confident of their idea??? Robert Byers

You yourself produced my kidneys; you kept me screened off in the belly of my mother.” (Psalm 139:13) Many of the chemical processes in your body release toxic substances and waste into your bloodstream. If allowed to remain, these would cause serious problems for you, even death. They have to be continuously filtered out and removed. This filtering is one of the principal functions of your kidneys. To visualize how the kidney works, imagine a stadium with thousands of spectators coming in for an event. First, the crowd must divide into numerous small lines. Then, the people in each line pass one by one through security gates, where individuals without tickets are turned aside. The spectators with tickets pass through to their assigned seats. Similarly, all the many elements making up your blood need to circulate throughout your entire body. As they do so, however, they must repeatedly pass through your kidneys by means of large blood vessels, the renal arteries, one for each kidney. After entering the kidney, the renal artery fans out into smaller vessels in the kidney’s inner and outer layers. The various elements in your blood are thus channeled into smaller and more manageable “lines.” Finally, the blood arrives at tiny clusters, each consisting of about 40 tightly looped, minute blood vessels. Each cluster, called a glomerulus, is surrounded by a two-layer membrane known as Bowman’s capsule. Together, the glomerulus and Bowman’s capsule make up the first part of your kidney’s ‘security gate,’ a nephron—the basic filtration unit of your kidney. There are over a million nephrons in each kidney. The blood cells and proteins in your bloodstream are indispensable. They provide your body with vital services such as oxygen supply, defense, and damage repair. To prevent the loss of blood cells and proteins, the first stage of filtration separates them from all other elements. This specialized task is accomplished by Bowman’s capsules. Blood vessels entering the glomerulus split up into tiny capillaries with very thin walls. Thus, blood pressure can force some water and other small molecules through their fine membranes, out of your bloodstream, and into Bowman’s capsule and the coiled tube connected to it. This tube is called the convoluted tubule. The larger protein molecules and all the blood cells remain in the bloodstream and continue to flow through the capillaries. Now filtration becomes more selective. Your kidneys must make absolutely sure that nothing of value to your body escapes! The fluid flowing through the tubule at this point is a watery mixture, consisting of dissolved useful molecules along with wastes and unwanted substances. Specialized cells along the tubule’s inner wall recognize useful molecules, such as water, salts, sugars, minerals, vitamins, hormones, and amino acids. These are efficiently plucked out by being reabsorbed into the tubule wall and passed back into the surrounding network of capillaries to reenter your bloodstream. The capillaries join up again as little veins that then combine to become the blood vessel called the renal vein. By it your blood, now filtered and cleansed, leaves the kidney and goes on to sustain life in your body. After studying anatomy and physiology at the high school and college levels and working in the medical field, it amazes me how people can examine (and I mean really examine) the human body and come to the conclusion that "it just happened" by mutations and natural selection. Barb