Human Sexual Behavior Chapter 3
Human Sexual Behavior Chapter 3 82679 - PSYC 3060 - 001
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This 6 page Class Notes was uploaded by Brenna Biggs on Saturday February 6, 2016. The Class Notes belongs to 82679 - PSYC 3060 - 001 at Clemson University taught by Bruce Michael King in Fall 2015. Since its upload, it has received 24 views. For similar materials see Human Sexual Behavior in Psychlogy at Clemson University.
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Date Created: 02/06/16
Human Sexual Behavior Chapter 3 Hormones and Sexuality THE ENDOCRINE SYSTEM Important for growth, metabolism, water retention, reaction to stress, the development and maintenance of the reproductive system Influence our sexual behavior Hormones: chemical substances that are released into our bloodstream by ductless glands Hormones released by one gland often cause another gland to release its own hormones Endocrine system: network of ductless glands Not all glands in the body are endocrine glands Testicles and ovaries are part of the endocrine gland system Testicles manufacture and release testosterone Ovaries produce the “female hormones” estrogen and progesterone Pituitary gland releases eight different hormones into the bloodstream Two of these have their effect on the ovaries and testicles, and are thus called gonadotrophins Women Folliclestimulating hormone (FSH): stimulates the maturation of a follicle in one of the ovaries Luteinizing hormone (LH) triggers ovulation Prolactin and oxytocin are important for milk production and release during breastfeeding Men FSH: stimulates the production of sperm in the testicles and to produce male hormones Brain controls the release of pituitary hormones Gonadotropinreleasing hormone (GnRH) is manufactured in the hypothalamus; controls the release of gonadotropins THE MENSTRUAL CYCLE At birth, each ovary has about 300,000 to 400,000 immature follicles Ovaries do not produce any new follicles during a woman’s lifetime Entire growth phase of a follicle takes at least 220 days When a girl reaches puberty, FSH from her pituitary gland allows one or more antral follicles to enter the final stage of growth, which takes a little less than a month During the menstrual cycle, the endometrium of the uterus thickens (supplied with lots of blood vessels) in preparation for implantation of a fertilized egg If the egg is not fertilized, endometrial tissues are discharged from the body, accompanied by bleeding (menstruation) Process will end at menopause, when the ovaries shrivel up Average woman will have about 400 menstrual cycles in her lifetime Average length of an adult human menstrual cycle is about 28 days Preovulatory Phase (Days 5 to 13) Pituitary secretes relatively high levels of FSH Growing follicle becomes a temporary endocrine gland, secreting increasingly higher levels of estrogen Estrogen is carried in the bloodstream back to the brain and pituitary, where it inhibits further release of FSH Also stimulates release of luteinizing hormone (LH) from the pituitary and promotes growth of the endometrium of the uterus Triggers a release of LH from the pituitary (called the LH surge) Ovulation (Day 14) LH surge signals the onset of ovulation within 12 to 24 hours Mature follicle (Graafian follicle) has moved to the surface of the ovary At ovulation, the follicle ruptures and the ripe ovum is expelled into the abdominal cavity, where it will soon be picked up by a Fallopian tube Cells that had surrounded it in the follicle remain in the ovary (the corpus luteum) Some women experience lower abdominal cramps for about a day during ovulation Egg remains ripe for about 24 hours, but sperm can live in a tube for up to 5 days Postovulatory Phase (Days 15 to 28) Cells of the corpus luteum begin to secrete large levels of progesterone along with estrogen after ovulation Progesterone inhibits further release of LH from the pituitary Further prepares the thickened endometrium in case the egg is fertilized If egg is fertilized, it continues through the Fallopian tube and implants in the endometrium Developing placenta produces human chorionic gonadotropin (HCG) Ensures that the corpus luteum will continue to secrete estrogen and progesterone to maintain the endometrium Menstruation (Days 1 to 4) Decline in levels of estrogen and progesterone causes a loss of the hormones that were responsible for the development and maintenance of the endometrium Endometrium is sloughed off and shed over a 36 day period Loss of estrogen Inhibits the release of FSH Results in the pituitary gland secreting FSH, and a new cycle begins LENGTH OF THE MENSTRUAL CYCLE During adolescence, most girls’ cycles average longer than 28 days Most adult women’s cycles do not last exactly 28 days Length of the menstrual cycle can be affected by stress, nutrition, illness, drugs and other women’s cycles MENSTRUAL SYNCHRONY AND PHEROMONES Pheromones: a substance secreted by an animal to the outside of that individual which is then received by another individual…of the same species, which then elicits some behavior of developmental response in the latter Human sexuality might be influenced by natural odorless body secretions Some undetermined natural body odor might cause women’s cycles to synchronize Studies also suggest that male pheromones may affect women’s menstrual cycles THE MENSTRUAL CYCLE AND SEXUAL DESIRE Only women and females of a few other primate species have menstrual cycles Females of other mammalian species have estrous cycles Women report feeling more attractive and desirable near ovulation Olfactory and visual perceptions also change around midcycle that might indicate increased sexual motivation Men tend to find women more attractive and are more attentive toward them during ovulation Human females can become sexually aroused at any time of the cycle ATTITUDES ABOUT MENSTRUATION: HISTORICAL PERSPECTIVES Biblical Hebrews regarded a menstruating woman as “unclean” or “impure” Sexual intercourse was forbidden for 7 days after a woman noticed menstrual blood ATTITUDES ABOUT MENSTRUATION TODAY Men and women tend to have negative feelings toward women during menstruating Majority of American men and women seldom initiate sex during menstruation More common among bettereducated young women, people in committed relationship, and women comfortable with their sexuality Menstruation is the safest phase of the cycle to have unprotected intercourse Menstrual Taboos Versus Menstrual Celebrations In many cultures, menstruating women are portrayed as sick, impure, or filthy Require that she remain in a small menstrual hut for an entire week Common practice to introduce menstrual taboos to young girls during initiation ceremonies held about the time of their first menstruation Some cultures do not have negative attitudes about menstruation (Japan) MENSTRUAL PROBLEMS Amenorrhea Absence of menstruation for 3 months or longer in women who previously had regular menstrual cycles; common among female athletes Oligomenorrhea: absence of menstruation for shorter or unevenly spaced intervals Common for menstrual cycles to be irregular during the first few years after menarche (a girl’s first menstrual period) Premenstrual Syndrome (PMS) Refers to a group of physical and/or emotional changes in the last 3 to 14 days before the start of a woman’s menstrual period Physical symptoms: bloating, breast tenderness, abdominal swelling, swollen hands and feet, weight gain, constipation, headaches Emotional changes: depression, anxiety, tension, irritability, inability to concentrate For the large majority of women the symptoms of PMS are mild Symptoms must regularly occur in a cyclic fashion before menstruation and must end within a few days after the start of menstruation to be true PMS For some women, premenstrual mood changes are severe More severe symptoms of PMS is premenstrual dysphoric disorder (PMDD) Current opinion is that the ovarian hormones act in combination with serotonin to produce the symptoms PMS is greatest in women who have a very negative attitude about menstruation Dysmenorrhea Painful abdominal cramps during menstruation Most common in young adult women 17 to 24 years old Primary dysmenorrhea: symptoms are not associated with any pelvic abnormalities Secondary dysmenorrhea: associated with pelvic abnormalities Result of overproduction of prostaglandins Heavy Bleeding (Menorrhagia) Heavy menstrual bleeding with every cycle Most common in women approaching menopause Medically can cause anemia Endometriosis Condition in which the endometrial tissue also grows outside the uterus Tissue grows and then breaks apart and bleeds during the menstrual cycle Blood cannot drain normally like the inner uterine lining Abnormal bleeding becomes surrounded by inflammation Scar tissue forms, in many cases causing adhesions Relief can often be achieved with hormone therapy that reduces estrogen levels Toxic Shock Syndrome Caused by toxins produced by a bacterium, sometimes results in death Most cases were in women who had used extraabsorbent tampons Staphylococcus bacterium needs oxygen to multiply Air pockets in tampons contain oxygen Tampons do not cause toxic shock Women who use tampons should change them three or four times a day REGULATION OF MALE HORMONES Hypothalamus, pituitary gland, and testicles operate in a feedback loop Release of GnRH from the hypothalamus causes release of FSH from the pituitary Increases in FSH stimulate production of sperm in the seminiferous tubules Testosterone production increases when GnRH from the hypothalamus stimulates release of LH from the pituitary gland Higher blood levels of testosterone then inhibit the production of GnRH Levels of FSH, LH, and testosterone in men are relatively stable Difference is in the hypothalamus of the brain, not in the pituitaries Why women show cycles in FSH and LH and men do not TESTOSTERONE AND SEXUAL DESIRE Considerable evidence for testosterone playing a role in sexual desire Men who are sexually active often have high testosterone levels Hypogonadal men (abnormally low levels of testosterone) show little interest in sex Loss of estrogen and progesterone at menopause does not reduce sexual desire Administration of testosterone enhances sexual desire Testosterone levels in women are related to amount of sexual behavior and desire Anabolic Steroids Most commonly used enhancement substances today Derivatives of testosterone Promote growth by enhancing protein uptake by the muscle cell When administered in proper dosages by a physician, often have therapeutic value for people recovering from illness or surgery Marked masculinizing effect in women, not reversed by discontinuing use of drugs KEY TERMS Adrenal glands Amenorrhea Anabolic steroids Corpus luteum Dysmenorrhea Endocrine system Endometriosis Estrogen Estrous cycle Follicle Folliclestimulating hormone (FSH) Follicular (proliferative) phase Gonadotropinreleasing hormone (GnRH) Gonadotropins Hormones Human chorionic gonadotropin (HCG) Inhibin Luteal (secretory) phase Luteinizing hormone (LH) Menarche Menopause Menorrhagia Menstrual cycle Menstrual taboos Menstruation Mittelschmerz Orchiectomy Ovaries Ovulation Oxytocin Pheromones Pituitary gland Premenstrual dysphoric disorder (PMDD) Premenstrual syndrome (PMS) Progesterone Prolactin Prostaglandins Testicles Testosterone Toxic shock syndrome (TSS)
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