Excretory+System+-+5th+Period

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5 facts The kidneys, the bladder, and their tubes all work together to form the urinary system. Waste that's left over from breaking down food and your body's other activities naturally builds up in your blood. Your blood passes through your kidneys and when this happens, your kidneys act like a filter to clean the waste from your blood. Then they mix the waste with a little water to create urine. The urine goes to your bladder, which you empty when you urinate (pee).

Kidneys normally come in pairs. If you've ever seen a kidney bean, then you have a pretty good idea what the kidneys look like. Each kidney is about 5 inches long and about 3 inches wide.

One of the main jobs of the kidneys is to filter the waste out of the blood. First, blood is carried to the kidneys by the renal artery. As the blood passes through the kidneys, it deposits used and unwanted water, minerals, and a nitrogen-rich molecule called urea. More than 1 million tiny filters inside the kidneys remove this waste. These filters, called nephrons, are so small you can see them only with a high-powered microscope.

The waste that is collected combines with water (which is also filtered out of the kidneys) to make urine. As each kidney makes urine, the urine slides down a long tube called the ureter and collects in the bladder, a storage 'bag' that holds the urine. When the bladder is about halfway full, your body tells you to go to the bathroom. When you urinate, the urine goes from the bladder down another tube called the urethra and out of your body.

Besides taking out your body's "trash," your kidneys help balance your body's vitamin and mineral levels so your other organs and bones can do their best work. They help in the production of red blood cells and produce a form of vitamin D, which promotes healthy bones. They also keep your blood pressure at a healthy level.

When you feel thirsty, your brain is telling you to get more fluids to keep your body as balanced as possible. If you don't have enough fluids in your body, the brain communicates with the kidneys by sending out a hormone that tells the kidneys to hold on to some fluids. When you drink more, this hormone level goes down, and the kidneys will let go of more fluids.

bibliography: http://www.voki.com/php/viewmessage/?chsm=4a0706ca830fb1d8ecb330f889f01e41&mId=962382 http://www.clccharter.org/donna/medschool/systems/system%20research/excretory/excretory.htm http://www.voki.com/php/viewmessage/?chsm=f16f7be33aeea3c55acea75bbbc896da&mId=962434 http://fcsdestiny.fultonschools.org/cataloging/servlet/presenttitledetailform.do?siteTypeID=-2&siteID=&includeLibrary=true&includeMedia=false&mediaSiteID=&bibID=634783&walkerID=1323906674955 http://fcsdestiny.fultonschools.org/cataloging/servlet/presenttitledetailform.do?siteTypeID=-2&siteID=&includeLibrary=true&includeMedia=false&mediaSiteID=&bibID=499824&walkerID=1323906733923