CK-12 Foundation
Ck 12: Life Science: Urinary System
[Free Registration/Login may be required to access all resource tools.] Sometimes, the urinary system is called the excretory system. But the urinary system is only one part of the excretory system. Recall that the excretory system is...
The Franklin Institute
Franklin Institute: Cutting Dead Cells
This site briefly explores how the integumentary system supports the excretory system in the removal of waste through the growth of hair, fingernails, and toenails.