State that the kidneys excrete urea and excess water and ions

The kidneys play a vital role in excretion by removing urea, excess water, and ions from the body.

• Urea is a waste product formed from the breakdown of proteins in the liver. It is toxic in high concentrations, so the kidneys filter it out of the blood and excrete it in urine to prevent toxicity .
• The kidneys also regulate the balance of water in the body. They adjust the amount of water excreted based on hydration levels, ensuring that excess water is removed while retaining necessary amounts .
• Additionally, the kidneys manage the excretion of various ions, such as sodium and potassium, helping to maintain electrolyte balance in the body. They can adjust the levels of these ions in urine depending on dietary intake and bodily needs .

Overall, through these processes, the kidneys help maintain homeostasis by regulating waste products and fluid balance.