AP PSYCHOLOGY

Detailed explanation-1: -Most hormones circulate in blood, coming into contact with essentially all cells. 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-2: -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-3: -Endocrine glands release hormones into the bloodstream. This lets the hormones travel to cells in other parts of the body. The endocrine hormones help control mood, growth and development, the way our organs work, metabolism, and reproduction. The endocrine system regulates how much of each hormone is released.

Detailed explanation-4: -Endocrine hormone are secreted into the blood and carried by blood and tissue fluids to the cells they act upon, while exocrine hormones are secreted into a duct, and then into the bloodstream.

Detailed explanation-5: -Hormones mediate changes in target cells by binding to specific hormone receptors. In this way, even though hormones circulate throughout the body and come into contact with many different cell types, they only affect cells that possess the necessary receptors.