Mechanism of Hormone Action

Hormones are the messengers of the endocrine system. Obviously, they change something in the cell. Hormones serve as the messenger molecules of the endocrine system. Endocrine hormones go throughout the body in the blood. However, each hormone impacts only certain cells tagged target cells. Target cells are the types of cells in which a hormone has an effect. Target cells are affected by a particular hormone because it has receptor proteins which are specific to that hormone. A hormone goes through the bloodstream until it finds a target cell with a matching receptor it can bind to. When the hormone plugs to a receptor, it leads to a change within the cell. The manner on how this works depends on whether the hormone is a steroid hormone or a non-steroid hormone.

Looking at Steroid Hormones in this study, steroid hormones are derived from lipids, like phospholipids and cholesterol. They are fat-soluble, so they can easily diffuse across the plasma membrane of target cells and tie with receptors in the cytoplasm of the cell. The steroid hormone and receptor produce a complex which goes into the nucleus and influences the expression of genes, essentially acting as a transcription factor. Examples of steroid hormones are cortisol and sex hormones. Asteroid hormone moves acrosses the plasma membrane of a target cell and binds with a receptor inside the cell.

To also consider the non-Steroid Hormones, non-steroid hormones are products of amino acids. sometimes they are not fat-soluble, so they are not diffuse across the plasma membrane of target cells. Instead, a non-steroid hormone glues to a receptor on the cell membrane. The tie of the hormone triggers an enzyme inside the cell membrane. The enzyme stirs another molecule, known as the second messenger, which influences the processes inside the cell. Some of the endocrine hormones are non-steroid hormones, eg insulin, and thyroid hormones. At the same time, a non-steroid hormone binds with a receptor on the plasma membrane of a target cell. Then, a secondary messenger affects cell processes.

Hormones work together by binding to protein receptors whether inside target cells or on their plasma membranes. The tie of a steroid hormone produces a hormone-receptor complex that affects gene expression in the nucleus of the target cell. The tie of a non-steroid hormone activates a second messenger that affects processes within the target cell.

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