HORMONAL REGULATION OF SEXUAL FUNCTION AND BEHAVIOR
The physiologic processes of sex are not only vascular and neuromuscular. An important part of sexual physiology is under the control of the endocrine system, which consists of ductless glands that produce chemical substances called hormones. Hormones are secreted directly into the bloodstream, where they are carried to tissues on which they act. Some hormones, such as Cortisol (made in the adrenal glands, which lie just above the kidneys), are necessary for life itself and influence a wide range of body functions. Other hormones are required for
reproduction or sexual development. Here, we will consider the hormones that influence our sexual function.
The most important hormone in sexual function is testosterone. This hormone, sometimes called the male sex hormone, is actually present in both sexes. In a normal man, 6 to 8 mg of testosterone are produced per day, with more than 95 percent manufactured in the testes and the remainder in the adrenal glands. In a woman, approximately 0.5 mg of testosterone is made daily in the ovaries and the adrenals.
Testosterone is the principal biologic determinant of the sex drive in both men and women. Deficiencies of testosterone may cause a drop in sexual desire, and excessive testosterone may heighten sexual interest. In men, too little testosterone may cause difficulty obtaining or maintaining erections, but it is not certain whether testosterone deficiencies interfere with female sexual functioning apart from reducing sexual desire. However, there is no evidence whatsoever to suggest that because women have less testosterone than men, they have lower sexual interest. Instead, it seems that men and women have different levels of behavioral sensitivity to the effects of this hormone, with women actually being more sensitive to small quantities in their circulation.
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