According to the U.S. Centers for Disease Control, heart disease, stroke, cancer, viral and bacterial respiratory diseases, diabetes, and chronic respirat

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Course Learning Outcomes for Unit VII Upon completion of this unit, students should be able to:

6. Describe human anatomical systems to include their disease states. 6.1 Describe aspects of the endocrine, skeletal, muscular, and nervous systems. 6.2 Describe various forms of birth control and sexually transmitted diseases (STDs).

Required Unit Resources Chapter 22: Human Sex Differences Chapter 23: Zika in Pregnancy Chapter 24: Study Drugs: Brain Boost or Brain Drain? Unit Lesson In this unit, we continue our study of the human body. In Chapter 22, “Human Sex Differences,” we explore the structures and functions of the skeletal system, muscular system, and endocrine system. In addition, we learn about basic differences between males and females in these two systems, as well as in other systems. Thyroid Hormone and Issues Have you ever wondered how the thyroid hormone was discovered? You may already know that thyroid hormone requires iodine, and if the body is deficient in iodine, the thyroid gland swells. This is called a goiter. More than 3,500 years ago, the Chinese were treating goiters with seaweed, which contains iodine. This is why iodine is included in our common table salt (Lynn, n.d.). British physician Thomas Wharton named the gland thyroid, which means shield, because its shape resembles that of an ancient Greek shield. It was not until 1888 that Swiss physician Theodor Kocher recognized that hypothyroidism could be successfully treated with desiccated thyroid. In 1909, Kocher won a Nobel Prize for his discovery. In 1914, American chemist Edward Kendall isolated thyroxine, but a way to manufacture the chemical cheaply was not developed until 1952 by Rosalind Pitt-Rivers, a British biochemist (Lynn, n.d.).

UNIT VII STUDY GUIDE Human Physiology

A swollen thyroid gland, known as a goiter (Bhandari, 2009)

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Andreas Vesalius, 16th Century Medical Titan

Andreas Vesalius was born in Brussels on the last day of 1514. At the age of 19, he began medical school at the Paris School of Medicine (Stewart, n.d.). At that time, the study of anatomy had been dominated for 1,300 years by the writings of a Roman physician named Galen, whose teachings were considered indisputable and irrefutable. Vesalius questioned Galen’s infallibility, which resulted in confrontations with his teachers. Because of war between Paris and the Roman Empire, he

transferred to the Louvain University to complete his medical studies, graduating with a bachelor’s degree in medicine in 1537 at 22 years of age (Stewart, n.d.). At 23 years of age, Vesalius was awarded his doctorate by the University of Padua, which then elected him to be the university’s professor of anatomy and surgery (Stewart, n.d.). In 1540, Vesalius was 25 years old when he began work on his crowning achievement, a fully illustrated medical textbook entitled De Humani Corporis Fabrica—The Structure of the Human Body. The work, which consists of around 700 pages bound in seven volumes, took approximately three years to complete. It was published in 1543 (Stewart, n.d.). Book printers at the time were just beginning to include illustrations in their books, and Vesalius’ book contained over 270. Many of these illustrations are acknowledged works of art, still memorable and beautiful in the field of medicine. In 1564, Vesalius became ill and passed away at the age of 49 (Stewart, n.d.). He was and remains a Titan in the field of medicine. Reproduction and Conception We hear a lot about fertility issues when people are trying to conceive children. Infertility can be caused by numerous difficulties. The impediment could be structural; after all, the structure of any object determines its function. It could also be related to chemicals. Wait—we are living beings, what would chemicals have to do with anything? The answer is that hormones are chemicals that are released by various glands. Have you had a friend try to conceive a child and was not successful? Remember, in order to form a child, an egg and a sperm must unite—this is only one of the many steps. The egg and sperm had to first be formed in the parents and then released. Once they united, forming a zygote, the zygote must implant into the wall of the uterus. Everything must be precise, and this preciseness is regulated by hormones. If everything goes well, conception occurs, the embryo develops, the fetus matures, and the baby is born. In Chapter 23, “Zika in Pregnancy,” we learn about the reproductive structures and functions of the male and female systems. Why are males physically stronger than females? Is male muscle stronger or better? Do males have more muscle mass? If you ever found a skeleton in the woods, you could actually identify its gender strictly from the skeleton, based on several structures. Whose pelvic area would be wider and have a larger angle? If you think about it, of course, you would realize that it would be the female, since a wider pelvic area aids in childbirth—it provides a larger passageway for delivery of a baby.

Left: Title page from De humani corporis fabrica, published in 1543 by Andreas Vesalius Above: Detail from the title page illustration showing Vesalius (center left) using a cadaver for a demonstration for students as well as members of the Church and the nobility (University of Glasgow Library, 2002)

(Imperial Magician, 1543)

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We learn the difference between sexual and asexual reproduction. We also learn about human development, birth-control methods, and sexually transmitted diseases (STDs). Considering the ever-growing population of the Earth and the personal nature of the subject, this is a very important chapter. Birth control pills are commonly used to prevent pregnancy, and other hormonal approaches work pretty much the same way. In our last unit, we read about negative feedback loops (Belk & Maier, 2019). One section of the brain is called the hypothalamus, and it stimulates the pituitary gland by producing gonadotropin releasing hormone (GnRH). Ovulation occurs because the pituitary gland releases luteinizing hormone (LH) and follicle stimulating hormone (FSH). These two hormones stimulate the ovary to produce estrogen, progesterone, and to ovulate (Seladi-Schulman, 2018). If the woman becomes pregnant, the placenta produces steady, increased amounts of estrogen and progesterone. These hormones negatively effect the hypothalamus and cause it not to produce GnRh. Without GnRH, the pituitary does not release LH or FSH, and the ovaries do not ovulate. Consequently, what hormonal contraception does is fool the body into “thinking” it is pregnant (Myers, n.d.). The ovaries do not ovulate during pregnancy. The thyroid system functions in a similar way, with the hypothalamus secreting thyrotropin-releasing hormone, the pituitary releasing thyroid- stimulating hormone, and the thyroid releasing thyroid hormone (Sargis, 2018 Sexually Transmitted Diseases (STDs) You may someday pass on what you learn now about human anatomy and reproduction to someone else. You may have children already, or you may be planning to have children. One day, you just might have to have “the talk” about sexual reproduction with one of your children. There are so many misconceptions and false information, it is important for children to learn the facts. We must help them understand that the choices they make about sex can have lasting effects on the lives of numerous people. With sex, pregnancy is not the only concern—another potential issue is sexually transmitted diseases (STDs). The incidence of STDs is on the rise (Saplakoglu, 2018). What we do today does affect what happens to our bodies in the future, as some STDs can cause problems later in life, such as cancer, infertility, problems with pregnancy, or chronic pain (Boskey, 2017). What are the most common STDs? Which ones can be cured? Which ones cause infertility? How can you tell if someone has an STD? If you cannot answer these questions, pay special attention to the information about STDs in this chapter; it could save your life. Nervous System In the last chapter of these two units, Chapter 24, “Study Drugs: Brain Boost or Brain Drain?” we learn about the system that controls most bodily functions, the nervous system. We learn about the various structures that make up the nervous system and what they do. We also learn about a variety of nervous system disorders.

Birth control pills (ParentingPatch, 2013)

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As you are reading this, there are a multitude of processes going on in your body. For example, your heart is beating, and your lungs are moving air into and out of your body. Did you eat recently? If so, you are digesting food. The list goes on and on. You decided whether you wanted to read the information on this page. Did you decide that your heart needed to beat or that digestion needed to occur? Thankfully, no, those processes are governed by our autonomic nervous system, and they occur automatically, without conscious thought or direction. Why do we have to consciously decide to do some things while others just happen automatically? How do we consciously decide to raise our arm, move our feet to walk, or use our eyes to read these words? Our brain and spinal cord constantly send electrical messages to control both autonomic and conscious activities. Do we take this for granted? Probably so. As long as everything works correctly, we rarely give it another thought; however, as with all organs and systems, problems can arise. Problems with the nervous system are not as easily fixed as, say, a broken arm or clogged coronary artery might be fixed. The brain is very delicate. We cannot explore a functioning brain or spinal cord because the electrical messages would be disrupted. You may remember that Ronald Regan had Alzheimer’s disease. You have probably seen commercials with Michael J. Fox promoting research for Parkinson’s disease. What are the differences between the two diseases? Can we treat them? Can we cure them? What promise does stem cell research hold for their treatment and cure? You may not have known anyone with either disease, but it is likely that you will at some point in your life. Why Learn About Health? You will be faced with voting for people who take stands on research that could possibly cure one or both diseases discussed above. For whom did you vote in the last presidential election? What was your candidate’s stance on this topic? If you do not know, you may have voted for someone who holds different values concerning various aspects and topics of health care than you do. Are political reasons the only reason we need to know about our body and health aspects? Of course not; we each have only one life and one body. This unit and the previous unit provided a foundation to help you understand how to care for your own body. Hopefully, you know enough now to ask useful questions about your health. Remember, preventing is generally easier, more effective, and less expensive than curing.

References Andreas Vesalius. (n.d.). Famous scientists. https://www.famousscientists.org/andreas-vesalius/ Belk, C., & Maier, V. B. (2019). Biology: Science for life with physiology (6th ed.). Pearson. Bhandari, J. S. (2009). Goiter [Photograph]. Wikimedia https://commons.wikimedia.org/wiki/File:Goiter.JPG Boskey, E. (2017). What could happen if I don’t get tested for STDs? The downfall of not taking control of

your sexual health. https://www.verywellhealth.com/what-could-happen-if-i-dont-get-tested-for-stds- 3132741

Grm wnr. (2005). Central nervous system [Image]. Wikimedia

https://commons.wikimedia.org/wiki/File:Central_nervous_system.svg

Diagram of a human nervous system; 1—brain, 2—central nervous system, 3—spinal cord (Grm wnr, 2005)

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Imperial magician [Print on the title page of De humani corporis fabrica by A. Vesalius]. (1543). https://www.biodiversitylibrary.org/item/191384#page/10/mode/2up

Lynn, J. (n.d.). The history of the thyroid gland. http://endocrinesurgeon.co.uk/index.php/the-history-of-the-

thyroid-gland Myers, A. (n.d.). What you need to know before taking birth control pills.

https://www.amymyersmd.com/2015/12/birth-control-pills/ ParentingPatch. (2013). Package of Lutera birth control pills [Photograph]. Wikimedia

https://commons.wikimedia.org/wiki/File:Package_of_Lutera_Birth_Control_Pills.jpg Saplakoglu, Y. (2018). STD rates keep rising as US ‘slides backward,’ CDC says.

https://www.livescience.com/63454-std-cases-rising-fourth-year.html Sargis, R. M. (2018). How your thyroid works. https://www.endocrineweb.com/conditions/thyroid/how-your-

thyroid-works Seladi-Schulman, J. (2018). Hypothalamus overview. https://www.healthline.com/human-body-

maps/hypothalamus#anatomy-and-function University of Glasgow Library: Special Collections Department. (2002). De humani corporis fabrica librorum

epitome. http://special.lib.gla.ac.uk/exhibns/month/sep2002.htm