MICROANATOMY

Detailed explanation-1: -Hormones are the messenger molecules of the endocrine system. Endocrine hormones travel throughout the body in the blood. However, each hormone affects only certain cells, called target cell s.

Detailed explanation-2: -The steroid hormones pass through the plasma membrane of a target cell and adhere to intracellular receptors residing in the cytoplasm or in the nucleus. The cell signaling pathways induced by the steroid hormones regulate specific genes on the cell’s DNA.

Detailed explanation-3: -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.

Detailed explanation-4: -Endocrine glands, which are special groups of cells, make hormones. The major endocrine glands are the pituitary, pineal, thymus, thyroid, adrenal glands, and pancreas. In addition, men produce hormones in their testes and women produce them in their ovaries.