From Regina Bailey,
Your Guide to Biology.
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Hormones are molecules produced and secreted by endocrine glands in the body. These hormones are released in the blood stream and travel to other parts of the body where they bring about specific responses from specific cells. Steroid hormones are derived from cholesterol and are lipid-soluble molecules.

How Steroid Hormones Work

Steroid hormones cause changes within a cell by first passing through the cell membrane of the target cell. Steroid hormones, unlike non-steroid hormones, can do this because they are fat-soluble. Cell membranes are composed of a phospholipid bilayer which prevents fat-insoluble molecules from diffusing into the cell.

Once inside the cell the steroid hormone binds with a specific receptor found only in the cytoplasm of the target cell. The receptor bound steroid hormone then travels into the nucleus and binds to another specific receptor on the chromatin. Once bound to the chromatin, this steroid hormone-receptor complex calls for the production of messenger RNA (mRNA) molecules through a process called transcription. The mRNA molecules are then modified and transported to the cytoplasm. The mRNA molecules code for the production of proteins through a process called translation.

Steroid Hormone Mechanism of Action

The steroid hormone mechanism of action can be summarized as follows:

1. Steroid hormones pass through the cell membrane of the target cell.
   
   
2. The steroid hormone binds with a specific receptor in the cytoplasm.
   
   
3. The receptor bound steroid hormone travels into the nucleus and binds to another specific receptor on the chromatin.
   
   
4. The steroid hormone-receptor complex calls for the production of messenger RNA (mRNA) molecules, which code for the production of proteins.
   
   

Anabolic Steroid Hormones

Anabolic steroid hormones are synthetic substances that are related to the male sex hormones. They have the same mechanism of action within the body. Anabolic steroid hormones stimulate the production of protein which is used to build muscle. They also lead to an increase in the production of testosterone. Testosterone is the hormone responsible for the development of male reproductive organs and male secondary sex characteristics. Testosterone is also critical in the development of lean muscle mass. Anabolic steroid hormones also promote the release of the growth hormone which stimulates growth, especially skeletal growth.

Abuse of anabolic steroid hormones disrupt the normal production of hormones in the body. There are several negative health consequences associated with anabolic steroid abuse. Some of these include infertility, hair loss, breast development in males, heart attacks, and liver tumors.

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