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StuDocu is not sponsored or endorsed by any college or universityChapter 5 - Summary Understanding Human SexualityHuman Sexuality (The University of Western Ontario)StuDocu is not sponsored or endorsed by any college or universityChapter 5 - Summary Understanding Human SexualityHuman Sexuality (The University of Western Ontario)Downloaded by breanna baric ([email protected])lOMoARcPSD|3232224
Human Sexuality – Chapter 5: Sex Hormones, Sexual Differentiation, and Menstruation-Many of the structural differences between males and females arise before birth, during the prenatal period, in a process called prenatal sexual differentiation Sex Hormones -Hormones are powerful chemical substances manufactured by the endocrine glands and secreted directly into the blood stream-The most important sex hormones are testosterone (one of a group of hormones called androgens) and estrogen and progesterone -These are secreted in the gonads, or sex glands: the testes in the male and the ovaries in the female The hypothalamus regulates the pituitary gland, which regulates other glands, such as the testes and ovaries Sex Hormone Systems in Males -The important hormone produced by the testes is testosterone Testosterone has important functions in stimulating and maintaining the secondary sex characteristics, maintaining the genitals and their sperm-producing capability, and stimulating the growth of bone and muscle -The pituitary produces several hormones, two of which are important in this discussion: follicle stimulating hormone (FSH) and luteinizing hormone (LH) These hormones affect the functioning of the testes, FSH controls sperm production, and LH controls testosterone production The levels of LH are regulated by a substance called gonadotrophin-releasing hormone (GnRH), which is secreted by the hypothalamus FSH levels are similarly regulated by GnRH The system comes full circle because the hypothalamus monitors the levels of testosterone present, and in this way testosterone influences the output of GnRH This feedback loop is sometimes called the HPG axis-The hypothalamus, pituitary, and testes work together in a similar negative feedback loop, ensuring that testosterone is maintained at a fairly constant level -Inhibin is another hormone produced in the testes – it acts to regulate FSH levels in a negative feedback look just as testosterone does with LH Cycles in Men -Studies have found that men’s testosterone levels displayed weekly fluctuations, peaking on weekends -Men who had a female partner and wanted to have a child with her displayed a 28-day cycle of testosterone levels, leading the researchers to hypothesize that men’s hormone cycles might have synchronized with their partner’s Sex Hormone Systems in Females -The ovaries produce two important hormones: estrogen and progesterone Estrogen brings about many of the changes of puberty (stimulating the growth of the uterus and vagina, enlarging the pelvis, and stimulating breast growth) Estrogen is also responsible for maintaining the mucous membranes of the vagina and stopping the growth of bone and muscle, which accounts for why women generally are smaller than men -

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