pearson reasoning and decision making quizlet chapter 11

Once outside the cell, they bind to transport proteins that keep them soluble in the bloodstream. Lipid-derived (soluble) hormones such as steroid hormones diffuse across the membranes of the endocrine cell. Depending on the location of the protein receptor on the target cell and the chemical structure of the hormone, hormones can mediate changes directly by binding to intracellular hormone receptors and modulating gene transcription, or indirectly by binding to cell surface receptors and stimulating signaling pathways. Receptor binding alters cellular activity and results in an increase or decrease in normal body processes. When the number of receptors decreases in response to rising hormone levels, called down-regulation, cellular activity is reduced. In up-regulation, the number of receptors increases in response to rising hormone levels, making the cell more sensitive to the hormone and allowing for more cellular activity. Additionally, the number of receptors that respond to a hormone can change over time, resulting in increased or decreased cell sensitivity. The number of receptors that respond to a hormone determines the cell’s sensitivity to that hormone, and the resulting cellular response. Cells can have many receptors for the same hormone but often also possess receptors for different types of hormones. For example, thyroid hormones act on many different tissue types, stimulating metabolic activity throughout the body. Receptors for a specific hormone may be found on many different cells or may be limited to a small number of specialized cells. 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.

Hormones mediate changes in target cells by binding to specific hormone receptors.

Discuss the role of different types of hormone receptors.

Pearson reasoning and decision making quizlet chapter 11