Chapter 11, Problem 19RA

Summary Introduction

To review:

1. The reason behind the use of the second messenger by the polar hormones.

2. The use of cyclic adenosine monophosphate (cAMP) as second messenger in hormone action.

Introduction:

Hormones are polar or nonpolar based on their structure as well as solubility in water. Polar hormones dissolve in water whereas nonpolar hormones dissolve in lipids. The plasma membrane is made up of phospholipid bilayer which allows only small uncharged and nonpolar molecules to pass through it. Large polar molecules or hormones cannot pass through the plasma membrane.