 Dear students, in this topic we shall discuss hormones and their general properties. The hormones are signaling molecules which are produced by the endocrine glands. They are transported by the blood to their respective target tissues. Hormones regulate the physiology and behavior of an animal. Dear students, we shall discuss in detail the properties of hormones. The first property of the hormone is that they act on specific target cells or tissues. The specificity of hormonal action depends on the types of receptors. A hormone comes in contact to all types of tissues in the body during circulation. This hormone acts only on its target cells because of the presence of receptors which are not present with every cell. Only the cells which have these receptors are affected by the hormone. The action of the hormone depends on the nature of the enzyme cascade which is linked to the receptor. The specificity of the receptor is that as a result of that, the chain of chemical reactions is only found in the cells which have the receptors. Moreover, the receptors are present but if the enzyme is different from the cascade, a hormone can be used on multiple actions. If two types of receptors are present for a hormone and two different types of tissues are present, then different types of enzyme cascades are also produced as a result of that. This is the reason that some hormones affect more than one tissue but they produce different effects. Here students, hormones are active at very low concentration. The first thing is that endocrine glands produce hormones in a very small quantity. The second thing is that these hormones are circulated through the bladder where they are diluted. So for tissues, the available concentration of a hormone lies between 10H2 power minus 8 to 10H2 power minus 12 molar. But all in all hormones are still active at this low concentration. The reason for this is that the hormonal actions are amplified. Because the binding of a hormone to its receptor leads to an enzymatic cascade. This enzymatic cascade has such steps in which the action of the hormone is actually multiplied or amplified. So just a few molecules of a hormone can modulate thousands or millions of molecular reactions within a cell.