Chapter 20, Problem 1CC

Does the apical membrane of a collecting duct cell have more water pores when vasopressin is present or when it is absent?

Summary Introduction

To determine: Whether the apical membrane of a collecting duct cell contains more water pores when vasopressin is present or absent.

Introduction: The excretory system of the body has a specialized organ called the kidneys. Kidneys have nephron where urine formation takes place. The nephrons have a duct called collecting duct.

Explanation of Solution

The cells present in the collecting duct can alter their permeability. The collecting duct contains a hormone called vasopressin. This hormone can add water pores in the apical membrane of the collecting duct. The membrane with more water pores helps the cells to retain more water. However, the apical membrane that does not contain the hormone vasopressin has no water pores. They are less permeable and reabsorb less water into the blood.

The apical membrane with vasopressin contains more water pores than the membrane that does not has vasopressin. The vasopressin hormone helps in the reabsorption of water into the blood.

Conclusion

The apical membrane of a collecting duct cell contains more water pores when vasopressin is present.