Module 3S2 Chemistry of Reproduction

2.3.1S2 page 3

Reflect and Connect

Prior to birth and on into old age, testosterone is being produced in the male reproductive system.  There are times in a male’s life when testosterone levels peak. See a visual representation of how testosterone levels fluctuate in the blood by completing the following graphing exercise. 

Module 3: Section 2—Lesson 1 Assignment

Testosterone and Male Development Graphing

Retrieve your copy of Module 2: Section 2—Lesson 1 Assignment that you saved to your computer earlier in this lesson. Complete the assignment. Save your completed assignment in your course folder. You will receive instructions later in this lesson on when to submit your assignment to your teacher.

Going Beyond

Testosterone levels should be within a normal range in both men and women. However, disorders of the body may need to be treated with various types of steroids. The use of anabolic steroids can have many harmful effects, yet there some body disorders that need treatment through this steroid use.  See if you can find out why steroids may be used to help treat individuals with HIV infection, Addison’s disease, arthritis or any other disorder you may find. 

Module 3: Section 2—Lesson 1 Assignment

Lesson Summary

Although gender is first controlled by the chromosome arrangement we receive from our parents, it is hormones that lead to sexual development, gamete production and the eventual continuation of the species.

Male hormone production begins in an embryo in the uterus. The process of sexual maturation happens during puberty, which begins with the increase in production of GnRH, from the hypothalamus. GnRH then causes the anterior pituitary to produce both FSH and LH. The production of FSH causes the testes to start producing sperm and the hormone inhibin, which feeds back negatively to the pituitary to control further production of FSH. While LH causes the testes to produce testosterone, high levels of the hormone provide a negative feedback control on the hypothalamus and pituitary to regulate LH production, thus also regulating testosterone production. Testosterone is then responsible for the proper development and maturation of the primary and secondary sex characteristics.

Chemical hormone control of the mature male reproductive system causes a peak in testosterone levels during three major times in a male’s life: in utero, at birth and during puberty. After puberty, testosterone levels stay at a steady rate for most of the remainder of a man’s life. Levels of testosterone can begin to drop at about age 40, a condition sometimes referred to as andropause in men. Although a male continues to produce testosterone throughout his life, sperm count is reduced as he ages.

Understanding the scientific effect of testosterone on the body has lead to the technological production of synthetic anabolic steroids. Although steroids can sometimes be used to treat disorders, like naturally low testosterone levels (called hypogonadism), anabolic steroids affect society in much greater way, through their misuse. The desire to look or perform better may lead some individuals to misuse anabolic steroids, even when people are informed of the risk factors involved.

Submit your completed Module 3: Section 2—Lesson 1 Assignment to your teacher for assessment.