Kidneys are pairs of organs located in the back stomach. Each kidney is important to keep your body balanced and well suited.
What do they do?Edit
Kidneys separates the waste from the nutrients using nephrons. Then, the nutrients are taken up to the body where it will be useful and help us with our other systems. Next, the extra water or wastes go down through a tube called the uterus, which then goes to your bladder.
When you go to the bathroom, you push the urine out of your bladder and it goes to the penis, which then pushes down the urine. Now, your healthy and the wastes are gone.
Are they useful?Edit
Yes, kidneys regulate water, in order for the human body to work like it's suppose to be, it must have the right amount of water. What the kidney does is it extracts excessive water from the body or retain water when the body needs more.
Kidney removes wastes, many of the blood and body fluids must have the right amount of water so the body can work properly. When the Kidneys are working properly, they extract excessive minerals, which is the urine, or "pee" you have.
Kidneys produce hormones, these hormones regulate some body functions such as the blood pressure.
So yes, without your kidneys you would have too much water, blood, excessive minerals (urine), and too much blood pressure. Thank your kidneys.
How can we protect our kidneys?Edit
Eat the right foods and exercise daily. Also, when you have to go and use the bathroom, its a good idea to go. Or else, you will form "solid concretion or crystal aggregation formed in the kidneys from dietary minerals in the urine," called Kidney stones. They form in the kidneys and hurts your body badly. Don't hold your urine inside your bladder, or you will get kidney stones.
Some kidney stones are easy to push out, simply by urinating, or "peeing". Some kidney stones could be taken out by surgery, basically if the kidney stones have been in your body for a while you'll probably have to get surgery to push it out.
Drink a lot of water also, and exercise a lot!