Lesson 2.3.1S2

Lesson 1—Male Hormones


Get Focused

Being male is a process that starts with a chromosomal arrangement founded at fertilization, and is not complete until maturation happens in puberty. In Unit B, Module 3-1, you were informed that being male meant the chromosomal arrangement of an X and Y chromosome. This chromosome arrangement then causes testosterone to start being produced. The secretion of testosterone then causes the formation of the male genitalia of a fetus in utero (in the uterus). The right timing and proper amount of testosterone produced helps mature the male reproductive system so that continuation of the species is possible.

 

Sam, from the Fertility Case Study, started going through puberty at 12 years of age. For boys, the age that puberty starts varies greatly, but is said to begin when gonadotropin releasing hormone (GnRH) production is increased by the hypothalamus. This hormone then activates the anterior pituitary to release follicle stimulating hormone (FSH) and luteinizing hormone (LH), sometimes referred to in males as interstitial cell stimulating hormone (ICSH). 

 

FSH then stimulates sex organ development, gamete production and leads to the Sertoli cells secreting inhibin. Inhibin then targets the anterior pituitary and hypothalamus to inhibit FSH, creating a negative feedback loop. LH or ICSH causes the interstitial cells in the testes to produce testosterone.

 

As Sam was going through puberty, both his primary and secondary sex characteristics were developing. The testosterone surge that occurred during puberty had an effect on his entire body by developing facial and body hair, deepening his voice, broadening his shoulders, narrowing his hips and developing more muscle mass.

 

By the time Sam was in high school and playing sports, he noticed that his muscle development was not the same as some of the other first line players on his football team. From the conversation Sam had with a couple of the players about a ‘juice’ mixture they were taking and their offer to get him some of the ‘juice’, he began to look into the chemical. Once he discovered that the juice was a mixture of anabolic steroids he wanted to learn what he could about normal male hormone production and function, so that he could compare this with what the effects anabolic steroids would have on his body. Without knowing what the functions of normal male sex hormone secretions are and the effects that steroids can have, Sam could not make an informed choice of whether to take the chemical or not.

 

Focusing Questions in this lesson are:

  • What are the male reproductive hormones?
  • How do hormones maintain homeostasis in the male reproductive system?
  • What role do the male hormones play in regulating the primary and secondary sex characteristics?

 

This lesson should take approximately 80 minutes.

Module 3: Section 2—Lesson 1 Assignment

Once you have completed all of the learning activities for this lesson, you can complete the online assignment.

Bio30 2.3.1S2 online assignment

Here is a tutorial video for this lesson that you can watch if it suits your learning style.  Bio30 tut#2.3.2S2 Male Hormones

** Any Self-Check and Try This questions in this lesson are not marked by the teacher; however answering these questions will help you review important information and build key concepts that may be applied in future lessons. You can respond to these mentally, write out your response, or record your answer in any other way that works for you.