Near Birth


42.12 The Development of Human Sex Organs The sex organs of early human embryos are similar. Male sex steroids (androgens) promote the development of male sex organs.Without androgen action, female sex organs form, even in genetic males.

Under the influence of androgens, a penis and scrotum form.

Without the influence of androgens, female external organs develop.

GnRH release increases, stimulating increased production of gonadotropins and hence increased production of sex steroids.

In females, increasing levels of LH and FSH at puberty stimulate the ovaries to begin producing the female sex hormones. The increased circulating levels of these hormones initiate the development of the traits of a sexually mature woman: enlarged breasts, vagina, and uterus, broad hips, increased subcutaneous fat, pubic hair, and the initiation of the menstrual cycle.

In the male, an increasing level of LH stimulates groups of cells in the testes to synthesize testosterone, which in turn initiate the profound physiological, anatomical, and psychological changes associated with adolescence. The voice deepens, hair begins to grow on the face and body, and the testes and penis grow. Androgens also help bones and skeletal muscles grow, especially when they are exercised regularly.

Natural muscle development can be exaggerated by both men and women who want to increase their maximum strength in athletic competition if they take synthetic andro-gens—called anabolic steroids. However, anabolic steroids have serious negative side effects. In women, their use causes the breasts and uterus to shrink, the clitoris to enlarge, menstruation to become irregular, facial and body hair to grow, and the voice to deepen. In men, the testes shrink, hair loss increases, the breasts enlarge, and sterility can result. You can understand the causes of some of these side effects by considering the negative feedback effects of sex steroids on the production of LH and FSH. Other side effects are even more serious. Continued use of anabolic steroids greatly increases the risk of heart disease, certain cancers, kidney damage, and personality disorders such as depression, mania, psychoses, and extreme aggression. Most official athletic organizations, including the International Olympic Committee, have banned the use of anabolic steroids.

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The Basics Of Body Building

The Basics Of Body Building

Bodybuilding is the process of developing muscle fibers through various techniques. It is achieved through muscle conditioning, weight training, increased calorie intake, and resting your body as it repairs and heals itself, before restarting your workout routine.

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