URINARY SYSTEM

The urinary system is responsible for ridding the body of many of its waste products. It also helps to maintain a stable environment by regulating the composition of body fluids. The waste substances are removed from the blood and expelled in urine, which is produced by the kidneys. Together, these two organs receive about one-quarter of the blood pumped out by the heart, and yet they contribute less than 1 per cent to our body weight.

KIDNEY SCAN

The kidneys filter the blood they receive so that waste substances and excess water pass into the urine. Substances that the body needs stay in the blood. The kidneys each contain huge numbers of nephrons, tiny structures that make urine and fine-tune its composition to maintain a stable environment in the body.

PARTS OF THE URINARY SYSTEM

The kidneys make urine, which flows down the ureters to the bladder. The bladder stores urine and expels it from the body via the urethra, a tube that is about 20 cm (8 in) long in men and 4 cm (11/2 in) long in women. Signals from the brain and spinal cord trigger emptying of the bladder.

KIDNEY GLOMERULI

Each kidney contains about one million glomeruli, tiny clusters of blood capillaries. Each glomerulus forms part of a nephron, one of the kidney’s filtering units. A glomerulus is the part of a nephron where water and waste products are forced out of the blood and carried away via a system of little tubes and ducts as urine.

Copyright © 2007 Dorling Kindersley

highlights

Vote Now for the Children's & Teen Choice Book Awards
Voting is open now through May 3 for the Children's and Teen Choice Book Awards — the only national book awards program where the winning author, illustrator, and books of the year are selected by young readers. Encourage your child to vote for his favorites today!

Find Today's Newest & Best Children's Books!
Looking for newly released books for your child? Try our new Book Finder tool to search for new books by age, type, and theme, and create reading lists for kids!

8 Products to Help Your Family Go Plastic-Free
How can you minimize your family's exposure to harmful chemicals and lessen your impact on the environment? Try swapping out some of your everyday plastic products with these non-plastic alternatives.

Registered for Kindergarten — Now What?
Wondering what to do now that you've signed your child up for kindergarten? Try our award-winning Kindergarten Readiness app! This easy-to-use checklist comes with games and activities to help your child build essential skills for kindergarten. Download the Kindergarten Readiness app today!

stay connected

Sign up for our free email newsletters and receive the latest advice and information on all things parenting.

Enter your email address to sign up or manage your account.

Facebook icon Facebook icon Follow Us on Pinterest

editor’s picks