The human kidney is a vital organ involved in both excretion and homeostasis.
What is meant by the term excretion?
Name one human organ, other than the kidney, that excretes a metabolic waste product.
The table below shows the concentration of two nitrogen-containing substances in blood plasma and in urine.
| Substance | Concentration in blood plasma (g per 100 cm3g\text{ per } 100\text{ cm}^3g per 100 cm3) | Concentration in urine (g per 100 cm3g\text{ per } 100\text{ cm}^3g per 100 cm3) |
|---|---|---|
| Proteins | 7.5 | 0.0 |
| Amino acids | 0.05 | 0.0 |
Name one metabolic waste substance normally found in urine.
Explain how the kidney ensures that proteins are not present in the urine.
Explain why the body does not excrete amino acids and how the kidney prevents their loss.
