BIOMOLECULES AND ENZYMES

Detailed explanation-1: -Endocrine glands make chemicals called hormones and pass them straight into the bloodstream. Hormones can be thought of as chemical messages. From the blood stream, the hormones communicate with the body by heading towards their target cell to bring about a particular change or effect to that cell.

Detailed explanation-2: -Endocrine glands secrete hormones directly into the bloodstream. The hormones dissolve in plasma and travel the circulatory pathways through various body tissues. So why do hormones affect only their target cells in particular tissues? Because only those target cells have receptors for that particular hormone.

Detailed explanation-3: -The glands of the endocrine system secrete hormones directly into the extracellular environment. The hormones then diffuse to the bloodstream via capillaries and are transported to the target cells through the circulatory system.

Detailed explanation-4: -A target cell responds to a hormone because it bears receptors for the hormone. In other words, a particular cell is a target cell for a hormone if it contains functional receptors for that hormone, and cells which do not have such a receptor cannot be influenced directly by that hormone.

Detailed explanation-5: -Endocrine hormones like estrogen are messenger molecules that are secreted by endocrine glands into the bloodstream. They travel throughout the body in the circulation. Although they reach virtually every cell in the body in this way, each hormone affects only certain cells, called target cells.