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Chapter 5- Human Sexuality.docx

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Psychology 2075

Chapter 5: Sex Hormones, Sexual Differentiation, and Menstruation o Prenatal Period= where structural differences between male and females arise process called Prenatal Sexual Differentiation Sex Hormones o Hormones= chemical substances secreted by the endocrine glands into the bloodstream o Fx felt rapidly and spread all over the body o Androgens= group of male sex hormones (Testosterone) o Testosterone: hormones released by testes in the male (lower levels in females) o Estrogen= group of female sex hormones o Progesterone= female sex hormone released by ovaries o Endocrine sex glandsTestes (male), Ovaries (female) o Hypothalamus regulates the pituitary glands (regulates levels of sex hormones) o Hypothalamus= regulates vital functions like eating,drinking and sexual behaviour o Master Gland= pituitary 3 lobes: anterior, intermediary and posterior  Anterior: interacts with gonads Sex Hormone Systems in Males o HPG Axis= hypothalamus-pituitary-gonad axis negative feedback loop that controls production of sex hormones o Hypothalamus= Gonadotropin-releasing Hormone (GnRH) which controls levels of.. o Pituitary= Follicle-stiumlating Hormone (FSH) + Luteinizing hormone (LH) o FSH sperm production o LH control testosterone production o Testes= Testosterone male hormone, stimulates secondary sex characteristics, maintaing genitals and sperm producing abilities, growth of muscle/bone o Negative feedback loop: LH tells Testes to make testosterone but when those levels get high the hypothalamus reduces its production of GnRH (LH levels reduce/Testosterone levels reduce) o One study showed that men’s testosterone levels displayd weekly fluctuations and that cycles might synchronize with partners o Inhibin= hormone made by testes (sertoli cells) regulates FSH levels in negative feedback loop just as testosterone does with LH o Contraceptive because suppresses FSH therefore sperm production Sex Hormone System in Females o HPG axis= similar to males but in ovaries o Hypothalamus GnRH o Pituitary FSH + LH : regulate estrogen and progesterone o Prolactin: makes milk, stimulates mammary glands o Oxytocin: ejection of milk, stimulates contractions during labor, snuggling hormone o Ovaries Estrogen + Progesterone o Estrogen: changes of puberty (secondary sex characteristics), maintains mucous membranes of vagina, stops growth of bone/muscle o Makes Inhibin controls FSH production in negative feedback loop of menstrual cycle The Menstrual Cycle o Unique to humans, apes, monkeys o Dogs/horses have estrous cycles o No bleeding only some spotting o Ovulation occurs when in ―heat‖/estrus slight spotting o Female animals only engage in sexual activity when in heat o Menstrual ovulation occurs midway between the periods of menstruation The Phases of Menstrual Cycle o 4 phases: each have hormonal, ovarian and uterine changes 1) Follicular Phase (Proliferative)  FSH high levels stimulate follicles in ovaries to mature egg and releases estrogen 2) Ovulation Phase release of mature egg, stimulated by LH surge due to high levels of estrogen stimulating GnRH/inhibits FSH 3) Luteal Phase (Secretory) LH turns follicle in to Corpus Luteum (makes progesterone)  High levels of progesterone inhibit LH, corpus luteum degenerates (sharp decline in estrogen/progesterone at end of phase)  Falling levels of estrogen stimulate FSH and starts again 4) Menstruation  shedding of the uterine lining (endometrium)  Triggered by: Estrogen/progesterone are low/FSH on the rise o Follicular Phase= high levels of estrogen growin the endometrium/thicken (proliferates) o Luteal Phase= progesterone released stimulates endometrium to release nourishing substances o Corpus Luteum makes estrogen/progesterone for 10-12 days and if not pregnant sharp decrease in these hormones at end of period (uterine lining shed) o Menstraul Fluid= Blood from endometrium + degenerated cells/mucus from vagina/cervix (2 ounces/4 tablespoons) o Menstrual Cup= reusable, enviro-friendly Length and Timing of Cycle o Average= 28 days but varies o Studies say women with higher variability in cycle have higher levels of androgens o Day 1-4/5= Menstruation o Day 5-13= Follicular Phase o Day 14= Ovulation o Day 15-28= Luteal Phase o In women with variation Luteal Phase stays constant (14 day range till mentruation) o Ex: 44 day cycle= ovulation on day 30 o Mittelschmerz (middle pain)= some woman say can feel abdominal pain on ovulation day o Ovulation does not always occur even if menstruation does= Anovulatory Cycle o Once/twice a year women in their 20s/30s o Common in puberty and menopause Other Cyclic Changes o 2 other processes: Cervical Mucus Cycle + Basal Body Temperature Cycle o Cervical Mucus Cycle glands in cervix that release mucus in menstrual cycle o Protects entrance of cervix: keeping bacteria out o Responds to changes in estrogen= increase in estrogen, mucus alkaline, thick o LH begins before ovulation= mucus becomes thin and watery make sperm passage easier  Dried it looks like fern-shaped pattern, detects for ovulation = Fern test o Basal Body Temperature low in follicular phase, dip during ovulation, rises after by .03 degrees, higher for rest of cycle o Progesterone= raises body temperature during Luteal phase (important for couples using fertility awareness method of birth control) Menstrual Problems o Dysmenorrhea painful/heavy menstruation, headaches, nausea, pressure and bloating of pelvis o Cause by high levels of Prostaglandins chemicals released by uterus causes muscles to contract o Uterine Contractions + lack of oxygen blood + heightened nerve sensitivity= menstrual cramps o Treatment NSAIDS= Ibruprofen (Advil), Naproxen (Aleve)  They are anti-prostaglandins  Orgasm helps relieve pelvic edema that causes discomfort o Endometriosis endometrial tissue grows outside of uterus (ovaries/fallopian tubes/vagina/rectum o Symptoms vary on location of growth: very painful periods, pain during sexual activity, infertility o Very serious could lead to sterility o Treatment Hormones or if very severe laser surgery o Amenorrhea absence of menstruation o Primary amenorrhea= no menstruation by age 18 o Secondary amenorrhea= if has had atleast 1 o Causes= pregnancy, genetic defects of reproductive system, hormonal imbalance, cysts/tumours, disease, stress, emotional factors related to puberty, strenuous exercise and anorexia Prenatal Sexual Differentiation Sex Chromosomes o Conception= single-cell, fertilized egg o 2 X chromosomes= girl o X and Y chromosome= boy o Gives instructions to organs on how to differentiate in course of development o Y has less info= 80 genes vs 1,090 genes in X o Different combinations other than XX/XY= abnormal syndromes o Klinefelters Syndrome XXY (extra X), testes abnormal, no sperm, testosterone low o 7 week after conception= starts to differentiate o gonads, 2 sets of ducts, external genitals Gonads o gonads become Testis at 7 weeks o Y chromosome= Sex Determining Region (SRY) o If TDF (testis-determining factor) is present= male If not female o X chromosome= genes that control ovaries and testes (sperm making) Prenatal Hormones and Genitals o After differentiation begin to produce diff sex hormones which directs rest of differentiation of genital system o Female= Wolffian Ducts degenerate o Mullerian ducts turn into fallopian tubes, uters, upper vagina o Tubercle= clit, Folds= inner lips, Swelling= outer lips o Male= Mullerian ducts degenerate, Wolffian Ducts support testosterone, turn into the epididymis, vas deferens, and ejaculatory duct o Tubercle= glans penis, folds= shaft, swelling= scrotum o 6 different hormones involved o mutation in anyone can cause error o 12 weeks= baby’s sex is clear based on external genitals Descent of Testes/Ovaries o Ovaries/Testes chaning in shape and position st o At 1 = ovaries/testes lie near top of abdominal cavity] th o 10 week= moved down to upper edge of pelvis o ovaries stay there till after birth then shift to adult pelvic position o testes is longer journey o Testes Passageway to scrotum= Inguinal Canal (several months after conception), canal closes after testes descend o 2 problems: testes fail to descend to scrotum at birth + Inguina canal doesn’t close off completely o Cryptorchidism (undescended testes) 2% of males, usually one is descended one isn’t  must be corrected by surgery or hormonal therapy  optimal before age 5 otherwise man will be sterile (high temp of testes inside body stop sperm making) o Inguinal Hernia  may reopen later in life, passageway through intestine and enter scrotum  Remedy= surgery Brain Differentiation o Prenatal hormones also act on brain o Hypothalamus (Preoptic area in animals)= sex-differentiated o Estrogen sensitivity binds to estroen receptors, if testosterone present during fetal development cells of hypo insensitive to estrogen o If estrogen present, highly sensitive to levels of etrogen o Crucial to HPG axis loop o Male hypothalamic cells= have more adrogen receptors, insensitive to estrogen o MRI studies show Males= larger volume of hypothalamus/amygdala (high density of estrogen/androgen receptors) o Plasticity of brain changing depending on experiences (not hard-wired like believed) o Ex: father who tosses football to son will have stronger neural circuit involed in catching and throwing vs girl next door who doesn’t Homologous Organs o Homologous=developed from same embryonic tissue o Analogous= similar function (see table 5.1 page 111) o Ex: ovaries and testes homologous= develop from und
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