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Department
Psychology
Course
PSYB64H3
Professor
Janelle Leboutillier
Semester
Winter

Description
Chapter 10: Sexual behavior Sexual chromosome abnormalities moms provide X chromosome to all offspring, fathers provides X for female or Y for males Turner when child receives only a single X chromosome (XO) instead of the usual pair (XX syndrome (XO) or XY) nd lack of 2 sex chromosome has impact on fertility, growth, hormone production associated with higher risk of diabetes, osteoporosis, cardiovascular disease normal female external genitals but ovaries develop abnormally dont produce ova or nomal levels of female hormones = infertility when X chromosome is missing in some but not all cells, or only portions of second X are missing, women may be fertile relatively short, increased skin folds at the neck spcific deficits in spatial relationships & memory can occur Klinefelter one of most common genetic abnormalities related to sex chromosomes syndrome (XXY) male, but usually experience reduced fertility and requires hormone treatment @ puberty to promote development of facial hair, deeper voice, development of external genitals, & to inhibit female characteristics such as breast development extra X chromosome can be due to interference with process of x-inactivation, where one X chromosome in each female cell is randomly silenced normal intelligence marked by mild cognitive difficulties and social awkwardness usually delayed & reduced verbal skills left-handedness more common, suggests it might affect brain lateralization or localization of specific fxns such as language in one hem or the other XYY boys appear to be taller and leaner, suffer from acne, higher risk for minor physical abnormalities of eye, elbow, chest IQ is slightly below average, fertile but more likely to produce sperm with chromosome abnormalities Higher rate of antisocial and criminal behavior, property crimes more than violence Abnormalities due to a 3 sex chromosome appear to have mild effects Sexual development 3 stages of prenatal development: Development Before 6 weeks after conception: both male and female fetuses have identical of Gonads primordial gonads that have capacity to develop into ovaries or testes After 6 weeks, a gene on short arm of Y chromosme (aka sex-determining region of Y chromosome SRY) is expressed in male embryos Testis-determining factor (protein encoded by SRY) switches on additional genes that cause primordial gonads to develop into testes Female embryos lack SRY gene Differentiatio Up until 3 month of deveopment, both male & female fetuses posses a male Wolffian n of internal system and a female Mullerian system organs Wolffian system = seminal vesicles, vas deferences, prostate Mullerian system = uterus upper portion of vagina, fallopian tubes Males: testosterone (or androgen) & anti-Mullerian hormone promotes development of Wolffian system Anti-Mullerian hormone inities degeneration of Mullerian system In female fetus: no additional hormones are needed for development www.notesolution.com Unlike testes, ovaries are not active during fetal development Nonfunctional remnants of Wolffian system remain throughout a womans life Androgen insensitivity syndrome (AIS) disrupts normal development of Wolffian system in males Lacks androgen receptors, so leads to development of female external genitalia, typical female gender identity & sexual behavior Anti-Mullerian hormone is still there, so female Mullerian system also fails to develop Results in shallow vagina and no ovaries, fallopian tubes uterus Development Male = penis & scrotum of external Female = labia, clitoris, outer part of vagina genitalia No hormonal activity is required in order to develop female external genitalia But males need a particular androgen: 5-alpha-dihydrotestosterone, must be recognized by receptor sites for male external genitalia to develop normally If genetic females are exposed prenatally to excess androgens, their external genitalia become masculinized females with congenital adrenal hyperplasia (CAH) show ambiguous external genitals Development average age of puberty has dropped dramatically over past century and a half at puberty phthalates are compounds frequently found in plastics and cosmetics, found to advance puberty in rats children are esp sensitive to small amounts of hormone, so increased exposure from external sources is cause for concern at onset of puberty, gonadotropin-releasing hormone (GnRH) is released by hypothalamus initiates release of 2 GnRH hormones by anterior pituitary gland: the follicle- stimulating hormone (FSH) and luteinizing hormone (LH) both sexes release them, but with diff effects in response to these hormones: testes begin to produce more testosterone, ovaries produce estradiol (and small amounts of opposite sex hormone) males: muscular development, maturity of external genitals, facial hair, enlargement of larynx (deeper voice) females: breast growth, , uterus, changes in fat dist, menstrual cycle 5-alpha-reductase deficiency: affects last step, maturation of external genitalia child is born with ambiguous genitalia but develops male secondary sex characteristics at puberty Sex hormones cholesterol is used to form sex hormones Aromatization is the only step necessary to turn testosterone into estradiol Both males and females have both testosterone and estrogen Males have more testosterone, females have more estrogen Sexual interest in females: Report slightly more interest around ovulation o Testosterone has greatest impact on womens sexuality o Estrogen & cognition: Best scores on spatial abilities tests when testosterone levels high and worst when estrogen levels are high o Best scores on verbal abilities and manual dexterity tests when estrogen levels are high Sexual interest in males: Testosterone levels increase in anticipation of competition o If androgen is in normal range, young mens testosterone levels dont predict sexual frequency o Married men have lower testosterone than single or recently divorced men www.notesolution.com
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