Physiology discussion

Physiology discussion ORDER NOW FOR CUSTOMIZED AND ORIGINAL ESSAY PAPERS ON Physiology discussion eating disorders discussion In this discussion, you will choose one eating disorder and analyze the treatment options available for that disorder as well as the rationale for their use based on the current understanding of the biological aspects of these conditions. Chapters 9 and 10 in your text analyze topics on neurotransmitters, receptors, and neurotransmitter systems, their role in feeding behaviors and satiety, and the impact of the pathology of selected eating disorders. The “ Psychological Treatment of Eating Disorders ”, article and the Nutrition and Eating Disorders video expand upon these topics to assist your integration of these concepts as applied to neuropsychological function and dysfunction. Include information on brain structures, nervous system pathways, neurotransmitters/receptors, and psychological, genetic, familial, lifestyle, and environmental factors when analyzing the etiologic theories. Additional emphasis should be placed on relating the proposed etiologic mechanism(s) of the disorder and the recommended treatment(s), as well as providing rationale(s) for treatment success or failure. Include treatments that are based on psychological, medical, pharmacologic (drug), and other available interventions. Physiology discussion You must use a minimum of one peer-reviewed source that was published within the last five years, documented in APA style. Minumum 250 words. Physiology discussion attachment_1 Physiology discussion. 10 Polka Dot/Thinkstock Regulation of Sexual Behavior Learning Objectives After completing this chapter, you should be able to: • • • • • • • Describe the process by which we become biological males and biological females. Explain the role of chromosomes and hormones in sexual differentiation. Name five different developmental disorders associated with missing or extra chromosomes or hormones. Identify differences between the male and female brain. Draw a graph that shows the changes in hormone levels in women throughout their menstrual cycles. List at least five sexual disorders in women. Explain the role of hormones in the maturation of the male reproductive system. wiL81028_10_c10_301-326.indd 301 7/10/13 12:31 PM Section 10.1 Sexual Differentiation CHAPTER 10 Molly is a girl who was born a boy. That is, she possesses the sex chromosomes of a male (one X and one Y chromosome), and she was born with testes and a scrotum. However, she was born without a penis, a rare defect known as cloacal exstrophy. Her surprised and dismayed parents elected for Molly to have reconstructive surgery that involved removing the testes and giving Molly the appearance of having female external genitalia. And Molly was raised a girl. She was dressed in girls’ clothing, given girls’ toys to play with, and socialized to be a girl. However, she was always a bit different, compared to other girls. She preferred the rough-and-tumble games of boys. In fact, she preferred playing with boys. By the time Molly reached puberty, she felt more like a boy than a girl, despite her family’s attempts to raise her as a girl. Molly’s story is similar to the stories of many children whose parents elected to raise them in a gender role that is not consistent with their biological sex. In a recent study, 14 out of 25 children who were reassigned sex at birth feel that they are the wrong sex (Reiner, Gearhart, & Jeffs, 1999). That is, in most cases biological boys who have been raised as girls feel like boys. This suggests that sex hormones affect the development of the brain before birth, making an indelible impression on the fetus that cannot be taken away by a surgeon’s knife. In this chapter we will look at how sex hormones affect behavior. We will examine their influence on physical development, perceptual ability, and sexual behavior. 10.1 Sexual Differentiation S exual differentiation, the process by which we become biological males or females, begins at conception. A female embryo develops when a sperm cell bearing an X chromosome and an egg or ovum, which always carries an X chromosome, are united. On the other hand, a male embryo develops when a sperm bearing a Y chromosome fertilizes an ovum. Recall from Chapter 2 that the Y chromosome is much smaller than the X chromosome and contains relatively little genetic material. In fact, the Y chromosome appears to have one function: to direct the development of the testes. The embryo has the ability to develop into a male or a female. Physiology discussion Physiology discussion. We all start out with the same equipment that is capable of taking a male or female form. The developing embryo has two primordial gonads (Figure 10.1). In an embryo with a Y chromosome, the Y chromosome directs the primordial gonads to develop into male gonads, or testes (Arnold, Chen, & Itoh, 2012). (Testis is the singular of testes.) wiL81028_10_c10_301-326.indd 302 7/10/13 12:31 PM CHAPTER 10 Section 10.1 Sexual Differentiation Figure 10.1: Sexual differentiation Sexual differentiation depends on whether the sperm was carrying an X or Y chromosome when it reached the ovum. Sexual appearance of baby at second to third month of pregnancy Genital tubercule Urethrolabial fold Genital groove Labioscrotal swelling Anus Female and male identical Sexual appearance of baby at third to fourth month of pregnancy Sexual appearance of baby at time of birth Genital tubercule Inner labial fold Vulval groove Anus Clitoris Labia majora Labia minora Anus Outer labial swelling Opening of urethra Opening of vagina Genital tubercule Urethral groove Anus Penis Scrotum Urethral fold Scrotal swelling Joining line of urethral fold Joining line of scrotal swellings Anus In the absence of the Y chromosome, the female reproductive system develops. The primordial gonad develops into the female gonad or ovary, when the Y chromosome is missing. The ovary can be characterized as the default gonad because it emerges if the Y chromosome is absent. wiL81028_10_c10_301-326.indd 303 7/10/13 12:32 PM Section 10.1 Sexual Differentiation CHAPTER 10 Organizational Effects of Hormones The gonads produce hormones, called gonadal hormones, which direct the development of the internal genitalia and external genitalia. During embryonic development, gonadal hormones have organizational effects, which are permanent and cannot be reversed. That is, gonadal hormones influence the development of the reproductive system and the nervous system (MacLusky & Naftolin, 1981). As soon as the testes develop, they begin to produce a hormone called testosterone. Testosterone is released into the bloodstream, where it travels to other parts of the body, including the brain. The developing brain is especially vulnerable to the effects of testosterone, which alters the formation of the hypothalamus, the cerebrum, and other areas, as you will learn later in this chapter. Testosterone also affects the development of the internal genitalia and external genitalia. Internal Genitalia Male internal genitalia are located inside the male’s abdomen and include the vas deferens, epididymis, and associated glands, such as the prostate gland. In the female body, internal genitalia include the vagina, uterus, and fallopian tubes. However, in the earliest embryonic stages, male and female alike have the ability to develop male or female internal genitalia. This is because embryos possess two sets of internal organs, called the Wolffian and the Mullerian ducts. The Wolffian ducts are the precursors of the male internal genitalia. Under the influence of testosterone, the Wolffian ducts flourish and develop into the internal plumbing of the normal male reproductive system. The testes also secrete another hormone known as Mullerian inhibiting substance. This hormone does exactly what its name implies: It inhibits the development of the Mullerian ducts, which means that the vagina, uterus, and fallopian tubes do not develop in the male body. Thus, the testicular hormones, testosterone and Mullerian inhibiting substance, orchestrate the development of the male internal reproductive system by stimulating the growth of the Wolffian system and preventing the growth of the Mullerian ducts. Physiology discussion Physiology discussion. Female internal genitalia, which arise from the Mullerian system, are the default structures that develop when testes and testicular hormones are absent. Because the ovaries develop in the female body, no Mullerian inhibiting substance is produced. In addition, the ovaries produce ovarian gonadal hormones, including estrogen and progesterone, which are believed to inhibit the action of testosterone in the female body (Novy & Resko, 1981). This means that the Wolffian ducts do not develop, because they require testosterone for their development, and thus they wither away. The Mullerian ducts, however, flourish and grow because there is no Mullerian inhibiting substance to prevent their development. Therefore, the vagina, uterus, and fallopian tubes grow and mature in the female body due to the absence of testosterone and Mullerian inhibiting substance. External Genitalia The final form of the external genitalia is also determined by the presence of testosterone. In its earliest stages, the embryo possesses a unisex external appearance. Both male and female embryos have protruding tufts of flesh called the genital tubercle, urethrogenital folds, and labioscrotal swellings (Figure 10.1). In the male’s body, testosterone is converted to dihydrotestosterone, which in turn changes the external appearance of the embryonic genitalia. The presence of wiL81028_10_c10_301-326.indd 304 7/10/13 12:32 PM Section 10.1 Sexual Differentiation CHAPTER 10 dihydrotestosterone causes the genital tubercle to transform into the glans (or head) of the penis, the urethrogenital folds to close up to form the body of the penis, and the labioscrotal swelling to become the scrotum that holds the testes. The testes actually descend into the scrotum later in development. In contrast, the external genitalia become female when dihydrotestosterone is not present. The genital tubercle transforms into the clitoris, the urethrogenital folds become the labia minora, and the labioscrotal swellings develop into the labia majora, in the absence of testosterone (Figure 10.1). The female reproductive system can be characterized as the default system: The body takes a female form if the Y chromosome or testicular hormones are missing, as you will learn in the next section. Variations in Sexual Differentiation For most individuals, sexual differentiation goes smoothly, and the body’s sexual appearance at birth is normal and appropriate for their chromosomal designation. However, some people develop abnormally due to genetic variations or exposure to hormone-like chemicals in the mother’s uterus (Hiort, 2000; Hiort & Holterhus, 2000). In this section we will consider a number of syndromes that alter sexual differentiation. Genetic Variations Human beings typically have 46 chromosomes, 22 pairs of autosomal chromosomes and 1 pair of sex chromosomes, as you learned in Chapter 2. Human males normally have the chromosomal designation 46, XY, whereas human females normally have the chromosomal designation 46, XX. It is important to keep in mind that not all people have 46 chromosomes. For example, some individuals have fewer than 46 chromosomes, as in the case of people with Turner’s syndrome; they are missing a sex chromosome and have a chromosomal designation of 45, XO. Because these individuals lack a Y chromosome, they do not develop testes and therefore do not produce testosterone or Mullerian inhibiting substance. This means that individuals with Turner’s syndrome have the “default body,” with female internal and external genitalia. However, because they are missing a sex chromosome, individuals with Turner’s syndrome have a sterile female gonad or ovary and cannot become pregnant. These individuals are raised as girls and develop with a female gender identity. They are typically short in stature and often have a short neck or a neck with a webbed appearance. In contrast, individuals with Klinefelter’s syndrome have the chromosomal designation 47, XXY. That is, they have an extra sex chromosome. Physiology discussion Physiology discussion. People with Klinefelter’s syndrome have functional testes, because they possess a Y chromosome, and therefore have typical male internal and external genitalia, although sometimes they have a penis that is smaller than normal. Keep in mind that the presence or absence of a Y chromosome determines whether or not testes will develop and whether or not testosterone will be produced. Whether a person has a chromosomal designation of XY, XXXY, or XXXXXY, the presence of a Y chromosome dictates that testes will develop and, as a consequence, that male internal and external genitalia will form. Individuals with a 45, YO chromosomal designation (an unpaired Y chromosome) have not been identified. Having an unpaired Y chromosome most likely results in miscarriage or embryonic death (Weekes, 1994). wiL81028_10_c10_301-326.indd 305 7/10/13 12:32 PM Section 10.1 Sexual Differentiation CHAPTER 10 Some individuals, referred to as true hermaphrodites, are born with both ovarian and testicular tissue. Typically, true hermaphrodites have a chromosomal designation of 46, XX. However, a fragment of the Y chromosome that directs the growth of testes is found on another chromosome in true hermaphrodites (Kojima et al., 1998; Margarit et al., 2000). This means that, although hermaphroditic individuals do not actually have a Y chromosome, they inherit a fragment of the Y chromosome from one parent, which causes one or more testes to be produced. Testosterone is produced by the testis and released into the bloodstream, where it promotes the growth of male internal and external genitalia. Mullerian inhibiting substance may or may not be produced, and thus the individual may or may not develop female internal genitalia. At puberty, estrogen produced by the ovary will stimulate the growth of breasts and curvature of the hips. If female internal genitalia are present, menstruation will begin. Because true hermaphrodites are usually born with a penis or a structure resembling a phallus, they are typically raised as boys, even if a vagina is also present. In this case surgical removal of the ovaries and other female organs is performed to enable the adoption of a male gender identity. On the other hand, when no phallus is present, a female gender assignment is usually given. Typically, the parents make gender assignments shortly after the individual’s birth. A number of investigators have questioned the appropriateness of gender assignment by the parents before the individual is able to choose the gender that is most comfortable for them (Fausto-Sterling, 1999; Kuhnle & Krahl, 2002; Nussbaum, 2000). Some genetic variations leading to faulty sexual differentiation are not due to the absence of a sex chromosome or to the presence of an extra sex chromosome. Instead, they are due to a mutation on an autosome. For example, some biological males with a chromosomal designation of 46, XY are born with female external genitalia. These males have a genetic mutation that causes a deficiency of the enzyme that prevents the conversion of testosterone to dihydrotestosterone (Cai et al., 1996). Recall that testosterone is capable of stimulating growth of the Wolffian system, but it cannot stimulate development of the penis and scrotum. Thus, these boys are born with male internal genitalia and female external genitalia. At puberty, however, the surge in hormonal release from the testes produces enough testosterone to stimulate the growth of the penis. To the amazement of the affected individual and family, the girl transforms into a boy as the penis grows, the testes descend into the scrotum, and secondary sex characteristics associated with the male body develop.Physiology discussion This condition is nicknamed guevedoces, or “eggs (testes) at twelve” (gueve- means “eggs” and -doces means “twelve” in Spanish). Although these individuals are raised as girls, they readily adopt a male gender identity, dressing and acting like men, after they develop male external genitalia (Imperato-McGinley, Guerrero, Gautier, & Peterson, 1974). Testosterone was present during brain development in these individuals, which may contribute to the adoption of a male sex role. Some individuals with this disorder do not adjust well to their life as a man, however (Aartsen, Gallee, Snethlage, & Van Geel, 1994). Another genetic mutation leads to a disorder known as androgen insensitivity syndrome. The word androgen refers to all male hormones, including testosterone. Individuals with this disorder have the chromosomal designation 46, XY. However, they are insensitive to the testosterone produced by their own testes. That is, because they have a Y chromosome, testes develop. The testes secrete testosterone and Mullerian inhibiting substance. The Mullerian inhibiting substance prevents the growth of the Mullerian system, which means that they do not develop a uterus or vagina. In addition, the individual’s insensitivity or inability to respond to testosterone prevents the development of the Wolffian system. Thus, the individual with androgen insensitivity syndrome has neither male nor female internal genitalia. The external genitalia, however, take the default female form because the individual’s body cannot respond to testosterone and acts as if no testosterone is present. When the child is born, it appears to be a girl and is raised female. wiL81028_10_c10_301-326.indd 306 7/10/13 12:32 PM Section 10.1 Sexual Differentiation CHAPTER 10 For many individuals with androgen insensitivity syndrome, no problem is noticed until puberty. At the time of puberty, these individuals may develop breasts due to the increased release of estrogen from the adrenal gland, but menstruation does not occur. A gynecological exam quickly reveals the problem: Undescended testes are found in the abdominal cavity, but no uterus or ovaries are found. Because such individuals are insensitive to testosterone and other androgens, hormone therapy cannot transform a woman with androgen insensitive syndrome into a man, even though she has a Y chromosome. Indeed, because the individual has been raised female and because testosterone has not affected the development of her nervous system, she is typically comfortable in that gender role and is happy to remain a woman. Estrogen hormone treatments stimulate the growth of breasts and other female secondary sex characteristics, although the affected woman will never be able to get pregnant because she lacks ovaries and a uterus. The “Case Study” describes the case of a young woman with androgen insensitivity syndrome (Hughes et al., 2012). Case Study: Androgen Insensitivity Syndrome Carolyn was a college freshman with an embarrassing problem. She had no vagina. Physiology discussion Physiology discussion. When she was 14, her mother took her to her gynecologist because she was worried that her daughter had not begun menstruating and showed few signs of sexual maturation. Because of Carolyn’s youth, the female gynecologist performed a pelvic exam by inserting a finger into Carolyn’s rectum. The gynecologist could not locate a uterus in Carolyn’s pelvis, but she did find two firm, egg-shaped structures that she knew were not ovaries. An ultrasound test and blood tests were ordered for Carolyn. The ultrasound confirmed the absence of a uterus and the presence of two testes in Carolyn’s pelvic cavity. The blood tests showed high levels of testosterone and very low levels of estrogen in her blood. What’s more, a chromosome test indicated that Carolyn had both X and Y chromosomes in each cell of her body. Very gently, the gynecologist told Carolyn and her mother that Carolyn had a rare disorder called androgen insensitivity syndrome. The doctor explained that Carolyn would never be able to have a baby because she had no uterus or ovaries. Carolyn didn’t understand much of what the doctor told her. At 14 years of age, Carolyn was not thinking about having babies. But she began to worry that nobody would marry her because she couldn’t have babies. The physician also told Carolyn that she had no vagina, but that she could have a vagina surgically constructed when she was older. Carolyn asked if doctors couldn’t also construct a uterus for her so that she could have babies. The doctor laughed softly, shook her head, and, using diagrams in a book, explained to Carolyn why only a vagina could be replaced. Carolyn blushed when the doctor showed her the pictures of women’s bodies, and she didn’t like talking about embarrassingly intimate parts of her body. The gynecologist asked for a family history because androgen insensitivity syndrome is so rare. Carolyn’s father had married the daughter of his first cousin, which meant that Carolyn and her mother shared one set of great-grandparents. Although the physician couldn’t say for certain whether that was why Carolyn had her unusual disorder, she assured Carolyn and her mother that most people with Carolyn’s disorder did not have close intermarriages in their families. Carolyn was placed on estrogen therapy, which caused her pubic hair and breasts to grow. Tall and lanky, she developed into a very attractive and feminine young … Get a 10 % discount on an order above $ 100 Use the following coupon code : NURSING10

Read more
Enjoy affordable prices and lifetime discounts
Use a coupon FIRST15 and enjoy expert help with any task at the most affordable price.
Order Now Order in Chat

Start off on the right foot this semester. Get expert-written solutions at a 20% discount