Module 3S2 Chemistry of Reproduction

Module 3S2 -Chemistry of Reproduction

Introduction

Hormone regulation, of the male and female reproductive system, causes the maturation of our gender development. Both male and female hormones are found in each gender, but in very different amounts. It is estimated that during our reproductive years men produce between 6-8 mg of testosterone daily but women only produce about 0.5 mg daily. Male hormones are produced at a more

steady rate and do not fluctuate as cyclically as female hormones do, specifically when considering the menstrual cycle. Sex hormone distribution is controlled by negative feedback systems that maintain the appropriate amounts of hormones for sexual maturation and function. As both men and women go through the aging process, there is a reduction in the quantities of sex hormones that are produced. 

In this section of Module 3, you will learn how hormones regulate both the male and female reproductive systems. You will study how the hormone feedback system in males initiates puberty, maintains a constant level of function through the reproductive years, and causes change in the aging process. In the case of females, you will examine the detailed hormonal control of the monthly menstrual cycle, the consequences to the cycle whether or not fertilization has occurred, and the hormonal action that results in menopause.

In This Module

In This Section

Section 2: Lesson 1—Male Hormones

In this lesson you will be learn to identify the male sex hormones and their effect on the primary and secondary sex characteristics. You will learn what effects aging has on the male reproductive system.

You will consider the following essential questions:

• 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?

Section 2: Lesson 2—Female Hormones

In this lesson you will learn to identify the female sex hormones and their effect on the primary and secondary sex characteristics. You will learn what effects aging has on the female reproductive system.

You will consider the following essential questions:

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

Section 2: Lesson 3—Phases of the Menstruation

In this lesson you will be able to identify when menstruation naturally begins and ends, as well as the different cycles and stages of the process of menstruation. You will be able to identify the hormones that control specific events that occur throughout menstruation.

You will consider the following essential questions:

• What are the physiological events of menstruation?
• What hormone(s) controls the specific events of menstruation?
• When does menstruation naturally begin and end?

Section 2: Lesson 4—Medical Use of Reproductive Hormones

In this lesson you will learn how technology helps in controlling reproductive hormones.

You will consider the following essential questions:

• What are the various effects of reproductive hormones?

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. 

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Explore

Hormone control of the male reproductive system is important for proper sexual development and gamete production. When the male sex hormones are secreted, how the hormones control sexual development and gamete production and what happens to the male reproductive system as aging occurs will be better understood as you do the following reading and view the video.

Read

By reading pages 492 to 495 of your textbook, you will review how the chromosomal sex of an individual is determined and how the male sex hormones cause male development of the embryo.  You will advance your learning by reading about how the male reproductive system is further developed and matured in puberty, as well as about the changes that occur throughout the aging process.

Watch and Listen

It is very important to understand when the main periods of hormone production occur, what the hormones produced are, what the function of each hormone is, and how the hormones are regulated in the male body. To help you further develop a clear understanding of the hormone control of the male reproductive system from utero, through puberty, and aging, watch the following video clip.

Watch the video clip, which will first look at normal function and control of the male sex hormones.

You should make summary notes on the material that you will be reviewing and store this information in your course folder. Remember that an excellent way to summarize hormone information is in the form of a feedback loop or a flow chart.

Male Reproductiive Hormones

Discuss

In the discussion board you have access to, discuss one, a few, or all of the following questions:

1. What can happen if the production of a hormone is not regulated properly?
2. Have you ever encountered any pressure to ‘beef-up’, meaning try anabolic steroids?
3. Do you think teens, such as yourself fully understand the implications of using steroids?
4. Is having the ‘right’ image of being male affecting young men today? If so how?

Self-Check

Test your understanding of the negative feedback control of the male sex hormones by correctly labeling the following Hormonal Control of Male Reproductive System diagram. Check your answers with your teacher or classmates and store your work in your course folder.

Label the numbered structures on the following diagram:

Inquiry into Biology (Whitby, ON: McGraw-Hill Ryerson, 2007), BLM14.3.1 Reproduced by permission.

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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.

Lesson 2.3.2S2

Lesson 2—Female Hormones

Get Focused

Although there is a lack of scientific understanding of the hormonal process that triggers an embryo to undergo female sexual development, there is a very good understanding of what happens during puberty, the menstrual cycle, and as a woman ages. Being female is designated by the chromosomal arrangement of two X chromosomes, which causes a female to develop female genitalia, begin having a menstrual cycle and undergo menopause. The beginning of the menstrual cycle allows the female to fulfill her role in the continuation of the species.

The beginning of puberty is similar in men and women. For women, as well as men, the beginning of puberty is defined when the hypothalamus begins producing more gonadotropin releasing hormone (GnRH). GnRH then stimulates the anterior pituitary to start producing both follicle stimulating hormone (FSH) and luteinizing hormone (LH). FSH and LH then act on the female gonads, the ovaries, to produce the female sex hormones estrogen and progesterone. Once estrogen and progesterone are secreted, they cause the maturation and development of the female primary and secondary sex characteristics, and the start of the menstrual cycle.

When Jane, from the Fertility Case Study – Couple 1 – was in high school, she was a competitive gymnast. Her skill level was very good and she was competing at the provincial and national level. In her Grade 11 year Jane was 17, she was 5-foot-3 and weighed 95 pounds. What most people did not know was that Jane had had an eating disorder since she was 10, and at 17, she had not yet started menstruating. When she started training in Grade 12, she was even more fragile looking than ever.  Her coach, being concerned about her well being, stopped her from competing in several early competitions and decreased her training by 2/3 of what she would normally do. The coach also contacted her parents, who were also concerned by the frail look of their daughter. 

Jane discovered that when a woman of reproductive age is placed under physically demanding training regimes, the stress of competition, and an eating disorder, her body may suffer from the absence of a menstrual period, called amenorrhea. 

Jane knew she wanted children in her life one day, so she decided to learn more about how normal female reproductive hormone control should be working, and how her training and eating disorder were affecting her reproductive system. To understand what was happening to her body she needed more information to make better decisions in her life now and in the future. 

Focusing questions in this lesson are:

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

Module 3: Section 2—Lesson 2 Assignment

No formal assessment will be given in this lesson. An assessment will be given after you have completed the lesson on the menstrual cycle.

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

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Explore

To understand how the female reproductive system is controlled by hormones, do the following readings and view the video. Remember to prepare complete summary notes, including labeled diagrams, flow charts, and feedback loops of the material you are learning. Store this information in your course folder.

Read

The hormonal control of the female reproductive system is much more complex than the male reproductive system. Read pages 495 to 499 to understand how puberty begins, to understand the control of the menstrual cycle, and to understand what happens at the end of the reproductive years in a female. Remember to make notes and illustrations to help you understand the secretion and control of the female sex hormones.

Watch and Listen

Watch the following video on:

Hormonal controls and the menstrual cycle.

Discuss

In the discussion board to which you have access, discuss one, a few, or all of the following questions:

1. When is a woman considered to be suffering from amenorrhea?
2. If a woman has very low levels of FSH and LH, how does this affect her reproductive system?
3. Should there be a minimum mass that female models and athletes need to meet in order to work professionally or complete?
4. Do you like the look of female body builders? Why or Why not?
5. How important is it to you to have a proper functioning reproductive system?

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Reflect on the Big Picture

Jane did do more research on the hormonal control of the female reproductive system where she found that “bone density relates closely to (1) menstrual regularity and (2) the total number of menstrual cycles. Delayed onset of menstruation and/or premature cessation of menstruation removes estrogen’s protective effect on bone. Young women who experience delayed onset of menstruation and women who are no longer menstruating are more vulnerable to calcium loss, which results in a decrease in bone mass.  Can you relate this fact to Jane’s appearance and develop a hypothesis to explain her frailty? Can this fact be related to the high frequency of osteoporosis in women in their menopausal years?

Once Jane understood the effects of the stress she was putting on her body, she sought help for her eating disorder and left competitive gymnastic competition. Later on, in her early twenties she started having a normal menstrual cycle.

Lesson Summary

To be able to perpetuate the species, females need to for their sexual hormones to be properly controlled. The proper control of the sexual hormones leads to a healthy reproductive system and a greater chance of having offspring. 

For women, puberty starts with the increase in GnRH, which then causes the pituitary to release FSH and LH hormones. These hormones help with sexual development, successful formation of functioning gametes, and continual movement through the menstrual cycle.

Stress, eating disorders and excessive exercise can play a major role in hormone function that can result in not having a proper menstrual cycle. 

Lesson 2.3.3S2

Lesson 3—Phases of Menstruation

Get Focused

The beginning of menstruation represents the beginning of a female’s reproductive years.  A female’s first period is called, menarche and is the start of a female’s individual reproductive cycle.  The start of the menstrual cycle is generally considered the pivotal event of puberty for females, and indicates the possibility of the event of fertility. The ability to be fertile means the ability to have offspring, and therefore the ability to help in the continuation of the species.

The menstrual cycle varies considerably among females, but on average is regarded to be 28 days in length. The menstrual cycle is controlled by reproductive hormones, whose effects divide the event into two interrelated segments. 

Just because a female begins menstruation does not mean that she is limited to doing only certain activities, or that there is a clear and easy path to fertilization. As you have been learning, there are many, many obstacles to fertilization and the birth of a healthy child. 

As the fertility doctor from the Fertility Case Study, you have identified that Sarah suffers from dysmenorrhea, and Jane from amenorrhea. To understand their disorder, both women needed to learn more about the structure and function of a healthy, properly functioning reproductive system, which includes a regular menstrual cycle. Understanding ‘normal’ function of the reproductive system then helped them to understand the disorders from which they were suffering, as well as the choice of treatment options that were available to them. 

In addition to menstrual problems, a clear understanding of the menstrual cycle is important to know when fertility can and cannot happen. This understanding is important for both men and women in family planning and prevention of unplanned or unexpected pregnancies.

Module 3: Section 2—Lesson 3 Assignment

In addition to the lesson work you complete for your course folder you will examine how the pituitary and ovarian hormones control and are controlled by the events of the menstrual cycles for assessment.

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

Bio30 2.3.3S2 online assignment

** The 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.

2.3.3S2 page 2

Explore

To understand the hormonal control of the female reproductive system, it is recommend to first do the reading and then watch the video segments. It is highly recommend that you make your own notes, particularly in the form of a flow chart or concept map, as well as a feedback loop illustrating the menstrual cycle. Store your work in your course folder for review later.

Read

To understand the regulation of the menstrual cycle, read pages 495 to 499, starting with the section titled ‘Sex Hormones and ending with the Female Reproductive System’ on page 499.

Watch and Listen

It is hard to separate female sex hormones from the menstrual cycle, so for the best understanding of the menstrual cycle, it is recommended that you review.

Module 3: Section 2—Lesson 3 Assignment

From the reading and videos you should now understand how the menstrual cycle is controlled by hormones.

Discuss

In the discussion board to which you have access, discuss one, a few, or all of the following questions:

1. What are medication-free ways of helping to have a pain free and/or regular menstrual cycle?
2. Why do females who live together often have menstrual cycles the happen at the same time?

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Going Beyond

There are as many differences in menstrual cycles as there are females in the world. Take some time now to do some research on common menstrual disorders such as: menorrhagia, hypomenorrhea, polymenorrhea and oligomenorrhea.

See if you can find what the difference is, specifically related to hormone control, between an estrus, or “heat period”, and a menstrual cycle.

Lesson Summary

Sexual maturation in females occurs with the onset of puberty. Puberty begins when GnRH is released from the hypothalamus and acts on the anterior pituitary to produce the reproductive pituitary hormones of FSH and LH. FSH and LH, then activate the female gonads, the ovaries, to produce the ovarian hormones, progesterone and estrogen, throughout the course of the ovarian and uterine events of the menstrual cycle.

The menstrual cycle is said to begin on the first day of bleeding and is usually a 28 day cycle. Both the ovarian and uterine cycles begin on this day. The ovarian cycle, which takes place in the ovaries, is divided into the follicular stage and the luteal stage. During the follicular stage, levels of FSH are high while stimulating normally one follicle to mature. The maturing follicle releases the ovarian hormones estrogen and progesterone. Estrogen then negatively feeds back to the pituitary to cause a reduction in the release of FSH.  Estrogen also causes the hypothalamus to secret GnRH, which then leads to an increase in the pituitary hormone of LH. LH activates ovulation of the primary oocyte from the follicle.

The end of ovulation is considered the end of the follicular stage and the start of the luteal stage.  With the release of the egg, the follicle develops into the corpus luteum under the influence of LH.  Both ovarian hormones are secreted from the corpus luteum and their increased levels feedback negatively to the anterior pituitary to inhibit production of FSH and LH. As the corpus luteum disintegrates, the ovarian hormone levels decrease in the blood. The low blood levels of progesterone and estrogen are detected by the anterior pituitary and cause an increase in FSH and LH; the cycle starts again. 

On the first day of menstrual flow, the corpus luteum degeneration causes estrogen and progesterone to be at low levels in the blood. Estrogen blood levels begin to rise as a new follicle begins to mature, releasing the ovarian hormone. When estrogen levels are high, it causes the endometrium thicken. A more rapid thickening of the endometrium lining occurs once the corpus luteum begins to produce progesterone, after ovulation has occurred. If fertilization takes place, the zygote travels through the oviduct and implants in the freshly, blood-engorged endometrial lining of the uterus. If fertilization does not occur, then there is a disintegration of the endometrium lining, and it is expelled from the body during menstruation.

Without this intricate dance of pituitary and ovarian hormones, the menstrual cycle would not take place, and there would be no possibility of fertilization.

Lesson 2.3.4S2

Lesson 4—Effects of Reproductive Hormones

Get Focused

Without proper hormonal control of the reproductive system, events like ovulation and sperm production cannot take place; this results in the lack of fertilization, and the failure to ensure continuation of the species. Normal hormone control may be altered knowingly, by taking hormones to enhance or prevent pregnancy and to treat disorders. Hormone control may also be altered unknowingly through the effects of endocrine disruptors. 

Male and female sex hormones are not only used to promote or avoid conceiving a child, but can also be used to treat other disorders. When the normal release of reproductive hormones is changed, the release of FSH and LH can be affected, which in turn reduces the development of egg and sperm. Progestin, synthetic progesterone, was the first chemical used as a female oral contraceptive, known as ‘the pill’. Varying quantities of estrogen and progesterone are used in today’s contraception pills.

Other conditions can also be treated with sex hormones. In the initial treatments using chemotherapy (the chemical treatment of disease), prostate cancer was treated with female sex hormones. Many types of cancer are now treated with female and male sex hormones. Menopause, andropause, impotence, low sperm count, arthritis and osteoporosis can be treated through the use of sex hormones.

Endocrine disruptors are synthetic or naturally occurring substances that interfere with the functioning of the body’s normal production of hormones. The endocrine disruptors can be absorbed into the body through contaminated water, food or air. Their effects can halt or stimulate normal hormone levels, or they may change how hormones travel in the body, affecting what the hormone controls. Some known human endocrine disruptors are dioxin, PCB’s, DDT and diethylstilbesterol (a drug known as DES). You may wonder if endocrine disruptors really affect humans.  “In the 1950s and 1960s, pregnant women were prescribed diethylstilbestrol (DES), a synthetic estrogen, to prevent miscarriages. Not only did DES fail to prevent miscarriages, but it also caused health problems for many of these women's children. In 1971, doctors began reporting high rates of unusual vaginal cancers in teenage girls. Investigations of the girls' environmental exposures traced the problem to their mothers' use of DES. The girls also suffered birth defects of the uterus and ovaries, and immune system suppression.” 

Exposure to endocrine disruptors during development can have permanent effects on an organism.  There is further evidence that endocrine disruptors may have consequences for many generations, not just for the immediate person or organism.

Remembering back to the Fertility Case Study, both Sam & Sarah, had hormone issues with their infertility problem. Sara used oral contraceptives for a long time prior to wanting to start a family, and Sam had misused anabolic steroids for many years.

Understanding how normal reproductive hormones control and affect the body can help you understand how these reproductive hormones are used to promote or reduce conception potential, to treat diseases, and how they are influenced by endocrine disruptors.

Keep the following focusing question in mind as you work through this lesson:

• What are the various effects of reproductive hormones? 

This lesson should take approximately 40 minutes.

Module 3: Section 2—Lesson 4 Assignment

In addition to the lesson work you complete for your course folder you will complete questions on endocrine disruptors in the environment for assessment. You are not required to hand an assignment in but please read the material presented.

Here is a tutorial video for this lesson that you can watch if it suits your learning style.  Bio30 2.3.4S2 Contraception

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Explore

Continue through this lesson by first making sure you understand the normal reproductive hormone control in both the male and female reproductive systems. After you have completed any review material you might need to consult, move on to the readings and media clips discussing endocrine disruptors.

Read

Most of the information on sexual reproductive hormone control has been covered in previous lessons. However, due to the complexity of these feedback systems, it is recommended that you review the readings and videos again. As a review you may want to go back over pages 492 to 499.  Specifically read page 501 of the textbook.

It is also recommended at this time to do a web search of the words endocrine disruptors, to gain further understanding of what they are, where they are found, and what effect they have on animals and humans alike.

Watch and Listen

Review the segments on male and female sex hormone control from lessons 1 and 2 of this section.

Module 3: Section 2—Lesson 4 Assignment

You may  complete all questions in “Endocrine Disruptors in the Environment” from page 501 of the textbook for extra practice. 

Discuss

Through your discussion board, share your thoughts on one, a few, or all of the following questions:

1. Do you feel that oral contraceptives are safe to take?
2. How well do you think governments control-test for endocrine disruptors in products that we use?
3. Do you think that your age group is sufficiently informed about endocrine disruptors?
4. How can we, as a society, break away from our over abundant use of soft plastics?
5. Did Canada make a wise decision to ban Bisphenol A?
6. Should we look at animal studies to determine how chemicals can affect humans?

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Lesson Summary

As a species we have managed to be able to control most aspects of our reproduction. Much of this control has come through major tinkering with our reproductive hormones. Hormones are used to prevent and/or assist pregnancies. Reproductive hormones are used in the treatment of conditions such as cancer and arthritis. Many chemicals that are used in products that promote improvement in our daily lives are now being identified as affecting our endocrine system. Evidence now supports that the use of reproductive hormones, although beneficial to us at times, is not only having adverse effects on human health, but is having an affect on many other organisms as well.

Module Summary and assessent

Module 3: Section 2—Summary

From the study of this module, you will have gained an understanding of the chemical control that governs human reproductive systems. You will have come to comprehend the importance of how hormones control the various events and cycles of human reproduction. Whether you are male or female, it is tempting and sometimes necessary to use technology to help maintain a balance of reproductive hormones to help with various effects on the body. By knowing the effects that reproductive hormones have on your reproductive system, it will help you make the best choices possible for maintaining your reproductive health. The understanding of how chemistry controls the various stages and phases of reproductive hormone control is important during puberty, but also in later in life and the aging process progresses.

Section Assessment

You should have completed the following assessment from this section.

Bio30 2.3.1S2 online assignment

Bio30 2.3.3S2 online assignment