My question is about the biology of the body.What special feature does the kidney or renal cell have that enhances it function in the human body?I am looking for a physical difference.  For...

 My question is about the biology of the body.What special feature does the kidney or renal cell have that enhances it function in the human body?

I am looking for a physical difference.  For example a nerve cell has spider like extensions call dendrites. 

Expert Answers
trophyhunter1 eNotes educator| Certified Educator

The cells you are referring to are the nephrons, tiny filters inside the kidney, located in the solid outer region of this organ. Nephrons are in a close association with capillaries, containing circulating blood along with wastes from the cells. As blood passes through the kidneys, nephrons filter wastes from the blood including salt, water and urea. Also, useful substances are filtered out at the same time, such as nutrients. Some water is reabsorbed into the circulating blood. The wastes exit the body as urine. The tight bundle of capillaries located by the nephron is called the glomerulus. Blood is under high pressure inside these capillaries and filtration occurs. From there, some of the filtrate enters a cuplike structure called the Bowman's capsule, part of the nephron. Next, reabsorption occurs as the filtrate passes through the tubule, another part of the nephron. Due to active transport, glucose, salt and nutrients return to the blood. Then, the concentration of water within the tubule is higher than outside in the bloodstream and osmosis occurs, returning much of the water to the circulating blood.  The final stage is secretion occurring in the last part of the nephron tubule. Here, wastes colllect as urine which contains excess salt, water and urea. The collecting tubule, which leads to the hollow part of the kidney sends the wastes there, as a urine flow. Urine will pass to the ureters and ultimately the urinary bladder for storage, until such time as a person excretes the urine.