BIOL310 assignment01

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Assignment 1 ( 30 marks ) 1. From an anatomical and physiological perspective, describe the menstrual cycle. Pay special attention to the hormonal changes during the cycle. (ovaries)When is a woman most fertile? What are the physical and emotional changes that tend to occur during this cycle, and why do these occur? ( 15 marks ) The monthly Menstrual Cycle (also known as a period) is a set of hormonal and physiological changes occurring in the female reproductive system that prepares the body for a possible pregnancy (Ekomaru, 2019). The length of the cycle is on average 28 days between two periods, however it varies from woman to woman. Internal female organs that play a role in the menstrual cycle are the uterus and ovaries, which are connected to the uterus by a fallopian tube (Rathus et al, 2020). The ovaries are located on both sides of the uterus and attached to the uterus by ovarian ligaments. The outer cortex and the inner medulla are the two components of the ovary. The cortex is where the eggs develop, whereas the medulla houses nerves and blood arteries (Gibson & Mahdy, 2020). Ovaries have two main functions: egg cell production and production of hormones estrogen and progesterone (Rathus et al, 2020). Estrogen has a variety of roles, including promoting puberty, regulating the menstrual cycle, helping in the maintenance of cognitive function and psychological well-being in older women. Progesterone also has multiple roles like regulating the menstrual cycle and preparing the uterus for pregnancy by encouraging the formation of the uterine lining (Rathus et al, 2020). The fallopian tubes connect the ovaries to the uterus in the female pelvis on both sides. They act as a conduit for egg transportation and fertilization (Han & Sadiq, 2020). Biology 310: Biology of Human Sexuality (Revision 4) : Assignment 1

The uterus allows a fertilized egg to implant and develop, it has the ability to grow during pregnancy to accommodate the growing fetus, and shrinks after delivery. The uterus has three layers, the outer layer called perimetrium, the middle layer called myometrioum and the inner layer called endometrium. When a reproductive cycle does not result in the fertilisation of an egg, menstruation occurs. Menstruation is the bleeding caused by the shedding of the endometrial tissue (Rathus et al, 2020). The monthly menstrual cycle is regulated by hormones that are secreted by parts of the brain called the hypothalamus and the pituitary gland, as well as the ovaries (Knudtson & McLaughlin, 2019). The pituitary gland produces luteinizing hormone (LH) and follicle- stimulating hormone (FSH), which promote ovulation and stimulate the ovaries to create estrogen and progesterone. Estrogen and progesterone stimulate the uterus and breasts to prepare for prospective conception (Knudtson & McLaughlin, 2019). Menstrual cycle has four phases: the follicular, or proliferative phase, the ovulatory phase, the luteal, or secretory phase, and menstrual phase (Rathus et al, 2020). The cycle begins at the proliferative phase, which commences at the end of menstruation and has a duration of approximately 9 – 10 days out of the total 28 days of the cycle. The changes that occur during this phase include development of the endometrium in the uterus, maturity of the eggs and preparation of the ovaries for ovulation (Rathus et al, 2020). The next phase is the ovulatory phase, during which the ovulation occurs. The follicle that developed in the ovary ruptures and releases the mature egg near the fallopian tube. In addition, during the ovulation the estrogen production reaches the highest point, and woman’s body temperature drops slightly at ovulation, which indicates that at this moment the woman is most fertile, and then rises by around 0.5°C the next day (Rathus et al, 2020). During the third, secretory phase, the ruptured follicle triggers Biology 310: Biology of Human Sexuality (Revision 4) : Assignment 1

secretion of large amounts of progesterone and estrogen, which causes the endometrium to release nutrients that will help a fertilized egg once it has been implanted in the uterine wall (Rathus et al, 2020). If the egg was not fertilized and did not get implanted in the uterus, the ruptured follicle decomposes, and the levels of progesterone and estrogen decrease. Once the levels are significantly decreased, they can not sustain the endometrium, which triggers the last phase of the menstrual cycle, the menstrual phase, during which the endometrium shedds and comes out of the body through the cervix and vagina in a form of menstrual bleeding (Rathus et al, 2020). Hormonal changes during the menstrual cycle have been related to significant emotional and physical changes. The emotional changes can include mood swings, depression and irritability. The physical changes include body aches such as abdominal pain and and breast tenderness that can happen usually during the luteal, secretory and menstrual phases. Another change could be increase in appetite, usually during the secretory phase. Increased sex drive could occur in proliferative phase (Laessle et al, 1990). Additional physical changes could include headaches, fatigue, bloating, and usually occur in the secretory or menstrual phases. Biology 310: Biology of Human Sexuality (Revision 4) : Assignment 1

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References Ekomaru, C. (2019). What happens during your period. 3D4medical from Elsevier . https://3d4medical.com/blog/what-happens-during-your-period Gibson, E., Mahdy, H. (2020). Anatomy, Abdomen and Pelvis, Ovary . [Updated 2020 Aug 15]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK545187/ Han, J., Sadiq, N.M. (2020). Anatomy, Abdomen and Pelvis, Fallopian Tube . [Updated 2020 Jul Biology 310: Biology of Human Sexuality (Revision 4) : Assignment 1

31]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK547660/ Knudtson, J., McLaughlin, J. E. (2019). Menstrual cycle - women's health issues. Merck Manuals Consumer Version. https://www.merckmanuals.com/en-ca/home/women-s-health- issues/biology-of-the-female-reproductive-system/menstrual-cycle Laessle, R.G., Tuschl, R.J., Schweiger, U., Pirke, K.M. (1990). Mood changes and physical complaints during the normal menstrual cycle in healthy young women. Psychoneuroendocrinology. 1990;15(2):131-8. https://pubmed.ncbi.nlm.nih.gov/2359810/ Rathus, S., Nevid, J., Fichner-Rathus, L., McKay, A., & Milhausen, R. (2020). Human sexuality in a world of diversity (6th Canadian ed.). Toronto: Pearson. Thiyagarajan, DK., Basit, H., Jeanmonod, R. (2020). Physiology, Menstrual Cycle . [Updated 2020 Sep 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK500020/ Biology 310: Biology of Human Sexuality (Revision 4) : Assignment 1

2. Describe the biological and physiological aspects of the sexual response cycle as described by Masters and Johnson. Note: Many researchers and sexual health educators feel the response cycle is incomplete. As part of your response, include your thoughts regarding whether the response cycle accurately represents what happens to the human system during sexual activity. Also, comment on the reasons why many researchers and educators feel it is incomplete. ( 15 marks ) The human sexual response cycle is a series of physical, psychological, and emotional changes that occur when the body is aroused and engages in sexual activity (Rowland & Gutierrez, 2017). Biology 310: Biology of Human Sexuality (Revision 4) : Assignment 1

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In 1966, William Masters and Virginia Johnson conducted a research on !0,000 participants and measured their anatomical and sexual responses. They are well-known for their contributions to sexual, psychological, and psychiatric research, especially for their four-phase model of the human sexual response cycle and their studies on sexual response in the elderly (Rowland & Gutierrez, 2017). Excitement, plateau, orgasm, and resolution are the four stages of the sexual response cycle. (Rathus et al, 2020). During the excitement phase, both men and women experience the initial physiological sexual arousal response, by feeling elevated heart rate, elevated breathing and elevated blood pressure. Additional responses include muscle tension, blood vessel enargement and flushing of the skin. In women, a surge of blood causes nipple stiffening, engorgement of the clitoris, labia majora, minora, and uterus, as well as a modest elevation of the uterine position. The vagina also changes by expanding and thickening of the walls, as well as changing the color from pink to a darker shade. This is also when vaginal lubrication begins. In men, the rush of blood induces penile erection and enlargement of the testes, and the scrotum elevates closer to the body (Rathus et al, 2020). During the second stage, the plateau phase, all the responses from the excitement phase like the breathing, the heart rate, the blood flow and the muscle tension are intensified. In women, the vaginal walls darken and the clitoris becomes more sensitive. The vagina fully expands and the uterus becomes fully elevated. The Bartholin glands provide extra lubricant in and around the vagina. In men, the testicles are dragged deeper into the scrotal sac, and preseminal fluid secreted by Cowper's glands may show at the penile entrance (Rowland & Gutierrez, 2017; Rathus et al, 2020). Biology 310: Biology of Human Sexuality (Revision 4) : Assignment 1

The orgasm phase signifies the pinnacle or sexual climax of excitement, although not all men and women achieve this stage. Orgasm is characterised by involuntary, rhythmic muscle spasms all over the body, as well as a feeling of exhilaration and tension reduction. In women, the pelvic muscles surrounding the vagina and uterus contract, followed by the release of built- up muscle tension. The autonomic response to ejaculation/orgasm in men is divided into two stages. In the first stage, known as emission, the vas deferens, seminal vesicles, and prostate cause the urethral bulb to swell with seminal fluid, with internal sphincter contraction shutting the bladder neck to prevent urine flow. In the second stage, the expulsion, the muscles surrounding the base of the penis contract, propelling semen outside (Rowland & Gutierrez, 2017; Rathus et al, 2020). Resolution is the final phase, which is indicated by a return to baseline. Muscles relax, blood pressure decreases, and breathing returns to a condition of prearousal. Erectile tissues return to normal as blood supply to the vaginal region reduces. Men have a longer refractory time than women, so they can't have another orgasm right away, according to Masters and Johnson. Women have a shorter refractory period than men, allowing them to have multiple orgasms in a short amount of time (Rowland & Gutierrez, 2017). Despite the fact that Masters and Johnson's model was designed to focus on physiological changes, it was critiqued for being too limited in its conceptualization. The model did not take into consideration the psychological factors of sexual response, such as sexual desire. In order for the body to get physiologically aroused, it needs to be interested in sex. The concept of desire encompasses a wide variety of psychological, emotional, and cognitive aspects of human sexual response. The desire stage necessitates subjective pleasure or a desire to be aroused, and it Biology 310: Biology of Human Sexuality (Revision 4) : Assignment 1

represents a cognitive and emotional incentive to seek and respond to sexual stimulation (Rowland & Gutierrez, 2017). In addition, Masters and Johnson’s model was critiqued as being male biased, in the sense that it is good at explaining male sexual experience but not so good at explaining female sexual experience. The model assumes that sexual desire is impulsive, involuntary, and unprompted. However many women's sexual responses do not suit this description. Because definitions of desire dysfunctions presume a level of spontaneous sexual desire, many women were diagnosed as dysfunctional when their sexual functioning was perfectly normal (Rowland & Gutierrez, 2017). Also, the model assumes that sexual response is a linear progression from stage to stage, without an ability for backward transition or missing stages. However, some women describe arousal coming before desire, with desire being the recognition of one's own aroused condition. Masters and Johnson were likely blind to such nuances since their highly selected and generally orgasmic samples did not represent the complete range of reactions found in most study samples (Rowland & Gutierrez, 2017). References Rathus, S., Nevid, J., Fichner-Rathus, L., McKay, A., & Milhausen, R. (2020). Human sexuality in a world of diversity (6th Canadian ed.). Toronto: Pearson. Rowland, D., Gutierrez, B. R. (2017). Phases of the Sexual Response Cycle. Psychology Faculty Biology 310: Biology of Human Sexuality (Revision 4) : Assignment 1

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Publications. Valparaiso University. 62. https://scholar.valpo.edu/psych_fac_pub/62 Biology 310: Biology of Human Sexuality (Revision 4) : Assignment 1

BIOL310 assignment01

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