SLG-BIOLOGY 2-5.0-5.2 PDF

Subject Code: Biology 2 Learning Guide Code: 5.0 Reproduction at the Organism Level Lesson Code: 5.2 The Ovarian and Uterine Cycles Time Frame: 60 minutes...

Subject Code: Biology 2 Learning Guide Code: 5.0 Reproduction at the Organism Level Lesson Code: 5.2 The Ovarian and Uterine Cycles Time Frame: 60 minutes Actual Time Component Task Time allocation Allocation Target Know the objectives. Hook Engage in the topic. 30 mins (Session 1) Ignite Comprehend the lesson. Navigate Perform the activity 30 mins (Session 2) Knot Take the assessment. MATERIALS NEEDED To complete this learning guide, you need the following: 1. pen; 2. paper; 3. phone/tablet/laptop; 4. stable internet connection; 5. Campbell Book 10th Edition TARGET After completing this learning guide, you are expected to: 1. determine the changes in the ovaries and endometrium during a monthly cycle; 2. describe the changes in the secretion of gonadotropins and ovarian hormones during a cycle; 3. explain positive and negative feedback mechanisms in the hormonal control of ovulation and menstruation; and 4. create a period calendar to predict when will ovulation and menstruation occur using the rhythm method. HOOK The pink ribbon represents support for Breast Cancer Awareness, while the use of the purple ribbon is usually observed during International Women's Day Celebration. Can you recognize what the teal ribbon represents? Figure 1. The use of ribbons to support advocacies. From “September is PCOS Awareness Month,” by Missouri Center for Reproductive Medicine (MCRM) Fertility, 2017 (https://www.mcrmfertility.com/2017/09/01/september-pcos- awareness-month/). PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 1 of 16  Various groups and organizations use ribbons as symbols of advocacies they support. The teal ribbon is used to raise awareness for anti-bullying, anxiety disorder, cervical and ovarian cancer, obsessive compulsive disorder (OCD), among others (Disabled World, 2020). But for the month of September, wearing the teal ribbon is a statement of support for raising awareness on Polycystic Ovary Syndrome (PCOS). September is celebrated as PCOS awareness month (PCOS Challenge: The National Polycystic Ovary Syndrome Association, 2020). PCOS is one of the most common endocrine and metabolic disorders affecting women of reproductive age (Escobar-Morreale, 2018). Even after the recent advances, the direct causes of this syndrome remain largely unknown thus the treatments available only relieves the symptoms. Watch the video below to obtain basic understanding about the disorder. https://www.youtube.com/watch?v=42Q4_XsWSjk Furthermore, PCOS is also one of the most misunderstood conditions. Access to vast array of information in a single click enabled the rampant spread of misinformation in various social networking sites. Misinformation feeds misconceptions. Educate yourselves about the common PCOS myths by reading the infographic in the link. https://www.hormone.org/- /media/hormone/files/infographics/myth_vs_fact_pcos_infographic.pdf THINK IT OVER Is PCOS a serious problem for women? Can it still be treated? In this learning guide, you will learn how the hypothalamic-pituitary-gonadal (HPG) axis regulates the female reproductive cycle and the changes it causes to the ovary and the endometrium. You will also try to predict the period of fertility and menstruation of a female using the rhythm method. IGNITE From the previous lesson, you have learned about the female reproductive system: Key Terms: paired ovaries, fallopian tubes, the uterus, the vagina, the external genitalia. This system produces the female gametes, provides the environment for fertilization, and holds the embryo during its complete development through the fetal stage until birth (Mescher, 2013). Female reproductive functions can be divided into two major phases (Guyton & Hall, 2006): (1) preparation for conception and pregnancy of the female body, and (2) the period of pregnancy itself. We will be focusing on the preparation of the female body for pregnancy. Females of reproductive age normally exhibit monthly cyclical changes in the ovaries and uterus due to the alterations in the rates of secretion of the female hormones. These changes constitute the female monthly reproductive cycle. One notable difference in the reproductive cycles between female animals is that coitus may be permitted at any time of the cycle in primates while other mammals are sexually receptive only at a particular time in their cycles, shortly before or after ovulation (Fox, 2011). PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 2 of 16  There are two closely linked reproductive cycles (see Figure 2) in human females resulting to two significant events (Guyton & Hall, 2006). First, in the ovarian cycle, the ovaries release a single ovum every month so that normally only a single fetus starts to grow and develop at a time. Second, in the uterine cycle also called menstrual cycle, the endometrium of the uterus is prepared in advance at the required time of the month for implantation of the fertilized ovum. Thus, the female reproductive cycle is actually one integrated cycle involving two organs, the uterus and the ovaries. Figure 2. The ovarian and the uterine cycles of the female reproductive cycle. From Campbell Biology (10th edition, p. 1026) by J. B. Reece, L. A. Urry, M. L. Cain, S. A. Wasserman, P. V. Minorsky, R. B. Jackson, 2014, USA: Pearson Education, Inc. © 2014 by the Pearson Education, Inc. The average duration of the cycle in human females is 28 days. Other women experience a cycle length that ranges from 20-45 days. The appearance of the initial uterine cycle characterized by the shedding of the blood-rich endometrium in a maturing individual is called menarche. When the cycles become irregular and eventually disappear, this phase is menopause (Eroschenko, 2008). The reproductive cycle is primarily controlled by the hormones secreted at differing rates by the hypothalamus, anterior pituitary, and ovaries throughout the various phases of the female monthly sexual cycle. Thus, to reiterate, the female reproductive cycle encompasses the ovarian and uterine cycles and its regulation caused by the changes in the hormonal levels. Hormonal Regulation of the Female Reproductive Cycle The term hypothalamic-pituitary-gonadal (HPG) axis refers to the hormonal interactions between the hypothalamus, anterior pituitary and the ovaries. The regulation of the female reproductive cycle is controlled by the three hierarchies of hormones secreted by these organs (Guyton & Hall, 2006). 1. Gonadotropin-releasing hormone (GnRH) - a releasing hormone secreted by the hypothalamus. PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 3 of 16  2. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) – sex hormones secreted by the anterior pituitary in response to the release of GnRH from the hypothalamus. 3. Estrogen and progesterone - hormones secreted by the ovaries in response to the sex hormones from the anterior pituitary gland. Gonadotropin-releasing hormone (GnRH) secreted by the hypothalamus controls the ovarian and uterine cycles. GnRH stimulates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. The ovarian changes that occur during the reproductive cycle particularly the secretion of estrogen and progesterone which cause changes in the endometrium of the uterus, depend completely on these gonadotropic hormones. The interplay of the hormones involved in the regulation of the female reproductive cycle, their functions and effects are summarized in Figure 3. *Red dashed lines signify negative feedback. Figure 3. Secretion and physiological effects of estrogens, progesterone, relaxin, and inhibin in the female reproductive cycle. From Principles of Anatomy and Physiology (14th edition, p. 1070) by G. J. Tortora, & B. Derrickson, 2014, New Jersey, USA: John Wiley & Sons, Inc. © 2014 by the John Wiley & Sons, Inc. FSH and LH are still absent throughout childhood, hence, the ovaries also remain inactive. When puberty starts, the pituitary begins to secrete progressively more FSH and LH, which leads to the onset of normal monthly sexual cycles. Phases of the Ovarian and Uterine Cycles The events in the ovarian and uterine cycles occur concurrently and are closely coordinated constituting the female reproductive cycle. Both cycles have distinct phases. Ovarian Cycle The ovarian cycle is a series of events in the ovaries that occur during and after the maturation of an oocyte (immature egg cell) also called ovulation. The duration of the follicular phase of the ovaries is from the first day of menstruation until the day of ovulation. While the luteal phase of the PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 4 of 16 ovaries takes place immediately after ovulation until the first day of menstruation (Mescher, 2013). As previously mentioned, the ovarian cycle is regulated by hormones. Shown in Figure 4 are the phases of the ovarian cycle and how hormones act and regulate the ovarian function. Figure 4. Phases of ovarian cycle and its hormonal regulation. From Junqueira’s Basic Histology Text and Atlas (13th edition, p. 458) by L. Mescher, 2013, USA: McGraw-Hill Education. © 2013 by the McGraw-Hill Education. Follicular Phase Follicular phase is the period of growth and development of ovarian follicles. This lasts usually from day 1 to about day 13 of the cycle although this duration is highly variable in women. Follicular growth is initiated by the FSH, while further development of the ovarian follicles is stimulated by the LH. Specifically, during this phase, some of the primary follicles grow, develop vesicles, and become secondary follicles (Mescher, 2013). Toward the end of the follicular phase, one follicle in one ovary reaches maturity as shown in Figure 5. The early growth of the primary follicle is stimulated mainly by FSH alone and as follicles grow, the granulosa cells secrete an increasing amount of estradiol (the principal estrogen). Two days before ovulation, estradiol reaches its highest concentration in the blood. The increased production of estradiol stimulates the hypothalamus to increase the frequency of GnRH pulses to which the pituitary responds to by secreting more gonadotropic hormones. This generates a positive feedback effect. As a result, there is formation of an increased numbers of FSH receptors in granulosa cells making it even more sensitive to FSH thus releasing more estradiol that will stimulate the pituitary to increase its LH secretion in the late follicular phase that culminates in an LH surge 24 hours before ovulation. This surge of LH acts to trigger ovulation. PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 5 of 16 Figure 5. Stages of Follicular Growth and Corpus Luteum Development in the Ovary. From Textbook of Medical Physiology (11th edition, p. 1013) by A. C. Guyton, & J. E. Hall, 2006, Philadelphia, USA: Elsevier Inc. © 2006 by the Elsevier Inc. Ovulation Ovulation (see Figure 5) in a woman who has a normal 28-day female reproductive cycle occurs at day14. This is characterized by the rupture of the graafian follicle releasing the secondary oocyte caused by the surge of LH. Ovulation occurs as a result of the sequential effects of FSH and LH causing swelling on the ovarian follicles. As the LH also converts the granulosa and theca cells into progesterone-secreting cells, the rate of secretion of estradiol begins to fall about 1 day before ovulation (Guyton & Hall, 2006). Luteal Phase After expulsion of the ovum from the follicle, the remaining granulosa and theca interna cells transformed into corpus luteum cells under the influence of LH in a process called luteinization. These enlarged structures become filled with lipid inclusions that give them a yellowish appearance (Fox, 2011) as seen in Figure 6. Figure 6. A corpus luteum in a human ovary. From Human Physiology (12th edition, p. 725) by S. L. Fox, 2011, New York, USA: McGraw-Hill Companies, Inc. © 2011 by the McGraw-Hill Companies, Inc. PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 6 of 16  The corpus luteum is a highly secretory organ. It secretes large amounts of both progesterone and estradiol (Tortora & Derrickson, 2014). Progesterone rises rapidly to a peak level during the luteal phase after ovulation, unlike before ovulation where its levels in the blood are negligible (see Figure 7). The high levels of progesterone combined with estradiol during the luteal phase exert an inhibitory, or negative feedback effect on FSH and LH secretion (Tortora & Derrickson, 2014). The corpus luteum also secretes the hormone inhibin to maintain low levels of FSH and LH. This suppression of the gonadotropic hormones from the anterior pituitary prevents the development of ovarian follicles to avoid multiple ovulations as part of the body’s preparation for an incoming pregnancy. During the late luteal phase, there is decreased production of inhibin. In the event that fertilization did not take place, the corpus luteum starts to degenerate resulting to the drop of estradiol and progesterone levels. Figure 7. Changes in the concentration of hormones involved in the reproductive cycle. From Principles of Anatomy and Physiology (14th edition, p. 1072 by G. J. Tortora, & B. Derrickson, 2014, New Jersey, USA: John Wiley & Sons, Inc. © 2014 by the John Wiley & Sons, Inc. Uterine Cycle The uterine or menstrual cycle is a concurrent series of changes in the endometrium of the uterus to prepare it for the arrival of a fertilized ovum that will develop there until birth. These changes in its structure and function is in response to the ovarian hormones estradiol and progesterone and are associated with impending implantation and nourishment of the developing organism. If fertilization does not occur, ovarian hormones decline, which causes the blood vessels in the endometrium to deteriorate and rupture and the functional layer (see Figure 8) to slough off as part of the menstrual flow or discharge. The cycle is subdivided into three phases: the proliferative, the secretory, and the menstrual phase shown in Figure 9. Figure 8. Layers of the endometrium. From Junqueira’s Basic Histology Text and Atlas (13th edition, p. 465) by L. Mescher, 2013, USA: McGraw-Hill Education. © 2013 by the McGraw-Hill Education. PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 7 of 16 Figure 9. Phases of endometrial growth during the female reproductive cycle. From Textbook of Medical Physiology (11th edition, p. 1019) by A. C. Guyton, & J. E. Hall, 2006, Philadelphia, USA: Elsevier Inc. © 2006 by the Elsevier Inc. Proliferative Phase The proliferative phase starts at the end of the menstrual phase after estradiol release. It occurs while the ovary is in its follicular phase. The increasing amounts of estradiol secreted by the developing follicles stimulate growth (proliferation) of the new functional layer lost during menstruation and the development of blood vessels in the endometrium. Estradiol also stimulates the production of receptor proteins for progesterone in preparation for the next phase (Eroschenko, 2008). Secretory Phase After ovulation, the secretory phase starts as a result of the progesterone secreted by the corpus luteum (Tortora & Derrickson, 2014). This secretion stimulates the development of uterine glands. As a result of the combined actions of estradiol and progesterone, the endometrium becomes thick, vascular (Eroschenko, 2008). The lipid and glycogen deposits increase in the uterine glands and the blood supply to the endometrium further increases. The purpose of these changes is to produce a highly secretory endometrium that contains large amounts of stored nutrients to provide appropriate conditions for implantation of a fertilized ovum. Menstrual Phase Menstrual phase starts when ovulated oocyte is not fertilized and no implantation occurs as a result of the fall in ovarian hormone secretion during the late luteal phase caused by degeneration of the corpus luteum (Guyton & Hall, 2006). Spiral arteries in the endometrium and are only present in primates become highly sensitive to declining hormone levels and constrict intermittently. Because of the inadequate blood supply in the cells of the functional layer, the cells die. Following constriction of the spiral arteries is its dilation leading to the rupture and detachment of the wall causing menstrual bleeding. Blood, uterine fluid, stromal cells, secretory material, and epithelial cells from the functional layer mix to form the menstrual flow. The summary of how hormones interact to regulate the ovarian and uterine cycles and the associated changes in the ovary and the uterus are shown in Figure 10 and 11. PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 8 of 16 Figure 10. Summary of hormonal interactions in the ovarian and uterine cycles. From Principles of Anatomy and Physiology (14th edition, p. 1072 by G. J. Tortora, & B. Derrickson, 2014, New Jersey, USA: John Wiley & Sons, Inc. © 2014 by the John Wiley & Sons, Inc. PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 9 of 16 Figure 11. The coordinated cycle of ovulation and menstruation affected by the changes in the levels of hormones. From Human Physiology (12th edition, p. 724) by S. L. Fox, 2011, New York, USA: McGraw-Hill Companies, Inc. © 2011 by the McGraw-Hill Companies, Inc. THINK IT OVER When declining levels of estrogens and progesterone stimulate secretion of GnRH, is this positive or a negative feedback effect? Why? Meanwhile, to better visualize the process and control of the female reproductive cycle, click on the link below. https://www.youtube.com/watch?v=WGJsrGm WeKE PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 10 of 16   progesterone Key Terms Checklist  Coitus  Oocyte  Menarche  Ovulation  Menopause  Ovarian follicle  Hypothalamic-pituitary-gonadal  Follicular phase (HPG) axis  Luteal phase  Uterus  Corpus luteum  Ovary  Luteinization  Gonadotropin-releasing hormone  Granulosa cells (GnRH)  Theca cells  Follicle-stimulating hormone  Inhibin (FSH)  Uterine cycle  Luteinizing hormone (LH)  Functional layer  Estrogen  Menstruation  Estradiol  Proliferative phase  Progesterone  Secretory phase  Ovarian cycle  Menstruation PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 11 of 16  NAVIGATE Materials: pen paper phone/tablet/laptop stable internet connection Campbell Book 10th Edition Procedure: Part I. (Non-graded) 1. Apply what you have learned by creating a period calendar. This activity simulates the natural family planning that uses the calendar/rhythm method. The rhythm method tracks the menstrual history to predict when the woman will ovulate. 2. Plot the events in the reproductive cycle for 2 months assuming that it follows a 28-day cycle. You may select any month/s in the current year 2020. 3. Illustrate the expected changes in the ovaries and uterus in the calendar and add appropriate notations on the various days of the month. You may also complete the activity using your computer. 4. Submit the soft copy (e.g. scanned copy) or the printed copy to your teacher. Month of ______ SUN MON TUE WED THU FRI SAT PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 1 of 16  Month of ______ SUN MON TUE WED THU FRI SAT PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 2 of 16  Part II. (Graded – 20 pts) 1. Fill in the blank boxes on the chart to determine how hormones control the female reproductive cycle. You may fill-out the chart using your computer 2. Submit the soft copy (e.g. scanned copy) or the printed copy to your teacher. From “ Activity 5-1: How Does the Menstrual Cycle Work?,” by CK-12 Foundation, n.d. (https://www.ck12.org/section/activities-and-answer-keys-%3a%3aof%3a%3a-the-menstrual-cycle--- teacher%27s-guide-%28human-biology%29/l). CC BY-NC PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 3 of 16  KNOT In summary, at the onset of puberty, the hypothalamus secretes the gonadotropin-releasing hormone (GnRH) which stimulates the anterior pituitary to release the sex hormones: follicle- stimulating hormone (FSH) and luteinizing hormone (LH). The production of FSH stimulates the growth, maturation, and secretion of estradiol of the ovarian follicle; this period is known as the follicular phase of the reproductive cycle. The rapid increase in the secretion of estradiol by the ovarian follicle causes a surge in the production of LH from the anterior pituitary; a positive feedback mechanism. The LH surge triggers ovulation. The LH also stimulates the conversion of the corpus luteum from the empty follicle which is an organ primarily responsible in the secretion of progesterone that is important in the maintenance of pregnancy; this marks the luteal phase of the cycle. The secretion of progesterone and estradiol rises during the first part of the luteal phase and exerts negative feedback on FSH and LH secretion. Without continued stimulation by LH, the corpus luteum degenerates at the end of the luteal phase leading to the decline in the secretion of estradiol and progesterone. This decline results in menstruation and the beginning of a new cycle. The rising estradiol concentration during the follicular phase causes the proliferative phase of the endometrium, while the secretion of progesterone during the luteal phase causes the secretory phase of the endometrium. REFERENCES CK-12 Foundation. (n.d.). Activity 5-1: How Does the Menstrual Cycle Work? Retrieved from https://www.ck12.org/section/activities-and-answer-keys-%3a%3aof%3a%3a-the-menstrual- cycle---teacher%27s- guide-%28human-biology%29/ Disabled World. (May 6, 2020). Awareness Ribbons Chart: Color and Meaning of Awareness Ribbon Causes. Retrieved from https://www.disabled- world.com/disability/awareness/ribbons.php#teal Eroschenko, V. P. (2008). Female Reproductive System. In diFiore’s Atlas of Histology with Functional Correlations Eleventh Edition (pp. 439- 467). Philadelphia, USA: Lippincott Williams & Wilkins. Escobar-Morreale, H. Polycystic ovary syndrome: definition, aetiology, diagnosis and treatment. Nat Rev Endocrinol 14, 270–284 (2018). https://doi.org/10.1038/nrendo.2018.24 Fox, S. I. (2011). Reproduction. In M. Lange (Ed.), Human Physiology Twelfth Edition (pp. 721-728). New York, USA: McGraw-Hill Companies, Inc. Guyton, A. C., Hall, J. E. (2006). Female Physiology Before Pregnancy and Female Hormones. In Textbook of Medical Physiology 11th edition (pp. 1011- 1026). Philadelphia, USA: Elsevier Inc. Mescher, A. L. (2013). The Female Reproductive System. In Junqueira’s Basic Histology Text and Atlas Thirteenth Edition (pp. 449-478). USA, McGraw-Hill Education. Missouri Center for Reproductive Medicine (MCRM) Fertility. (2017). September is PCOS Awareness Month. Retrieved from https://www.mcrmfertility.com/2017/09/01/september-pcos- awareness-month/ PCOS Challenge: The National Polycystic Ovary Syndrome Association. (2020). September is Polycystic Ovary Syndrome (PCOS) Awareness Month. Retrieved from https://pcoschallenge.org/pcos-awareness- PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 4 of 16  month/#:~:text=September%20is%20Polycystic%20Ovary%20Syndrome,that%20affects%20 women%20and%20girls. Reece, J. B., Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P.V., Jackson, R. B. (2014). Animal Reproduction. In B. Wilbur (Ed.), Campbell Biology Tenth Edition (pp. 1013-1036). USA: Pearson Education Inc. Tortora, G. J., Derrickson, B. (2014). The Reproductive Systems. In B. Roesch (Ed.), Principles of Anatomy and Physiology 14th Edition (pp. 1069-1088). New Jersey, USA: John Wiley & Sons, Inc. Prepared by: Leody Mayme A. Monteveros Special Science Teacher I PSHS-SOUTHERN MINDANAO CAMPUS Reviewed by: Virna Jane M. Navarro Special Science Teacher IV PSHS-WESTERN VISAYAS CAMPUS Approved by: Michelle B. Ducusin Special Science Teacher V/Team Lead (Biology) PSHS-ILOCOS REGION CAMPUS PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Biology 2: SY 2020-21 Biology 2-G10 Page 5 of 16