Excretory system.notebook 1 March 03, 2015 Mar 312:12 PM The Excretory System Mar 312:12 PM Kidney/bladder stones Mar 312:12 PM Mar 312:12 PM • Excrete: to get rid of waste • CO2 is breathed out through the lungs • Ammonia is very toxic and tough to get rid of • When proteins are broken down, ammonia is left over • The liver converts ammonia to urea in a process called the urea cycle • Where does urea go? Mar 312:12 PM Mar 312:12 PM Mystery fluid! • 0.9 g/L of sodium • 0.2 g/L of potassium • 0.015 g/L of calcium • 0.0013 g/L of magnesium • 0.84 g/L of sodium • 0.22 g/L of potassium • 64 g/L of sugar