ANATOMY

Detailed explanation-1: -All classes of hormones elicit the majority of their physiological effects via specific receptors which are located in three separate compartments of target cells: cell membranes (peptide and glycopeptide hormones), cytoplasm (steroid hormones) and nucleus (thyroid and steroid hormones).

Detailed explanation-2: -However, a given hormone usually affects only a limited number of cells, which are called target cells. A target cell responds to a hormone because it bears receptors for the hormone.

Detailed explanation-3: -Hormones vary in their range of targets. Some types of hormones can bind with compatible receptors found in many different cells all over the body. Other hormones are more specific, targeting only one or a few tissues.

Detailed explanation-4: -Examples of steroid hormones include cortisol and sex hormones. A steroid hormone crosses the plasma membrane of a target cell and binds with a receptor inside the cell.

Detailed explanation-5: -So why do hormones affect only their target cells in particular tissues? Because only those target cells have receptors for that particular hormone. Some hormones bind to receptors on the surface of target cells. Others enter the cells and bind to receptors in the cytoplasm or nucleus.