When the body needs to conserve water the kidneys excrete a

When the body needs to conserve water, the kidneys excrete a hypertonic urine. What do the terms Isotonic and hypertonic mean? Since the fluid that is to become urine begins as plasma (an isotonic solution), what must happen change it to a hypertonic urine? Explain.

Solution

Answer

An isotonic solution refers to two solutions that have same concentration of solutes, where as a hypertonic solution is the one where the concentration of solutes is greater than the other solution.

So, the fluid that is to become urine begins as plasma is isotonic

When this fluid passes through the different parts of Nephron (Bowmans capsule, Proximal convoluted tubule, distal convoluted tubule) it looses only water but not solutes

Hence, the urine becomes more and more concentrated.

This is known as hypertonic urine