Y khoa, dược - The reproductive system

27The Reproductive System27-2Learning Outcomes27.1 List the organs of the male reproductive system and give the locations, structures, and functions of each.27.2 Describe how sperm cells are formed.27.3 Describe the substances found in semen.27.4 Describe the process of erection and ejaculation.27-3Learning Outcomes (cont.)27.5 List the actions of testosterone. 27.6 Describe the causes, signs and symptoms, and treatment of various disorders of the male reproductive system.27.7 List the organs of the female reproductive system and give the locations, structures, and functions of each.27.8 Explain how ova develop.27-4Learning Outcomes (cont.)27.9 List the actions of estrogen and progesterone.27.10 Explain how and when ovulation occurs. 27.11 Describe what happens to an ovum after ovulation occurs.27.12 List the purpose and events of the menstrual cycle.27.13 Define menopause and explain what causes it.27-5Learning Outcomes (cont.)27.14 Describe the causes, signs and symptoms, and treatments of various disorders of the female reproductive system.27.15 Explain how and where fertilization occurs.27.16 Describe the process of implantation.27.17 Explain the difference between an embryo and a fetus.27-6Learning Outcomes (cont.)27.18 Describe the changes that occur in a woman during pregnancy.27.19 List several birth control methods and explain why they are effective.27.20 List the causes of and treatments for infertility.27.21 Describe the causes, signs and symptoms, and treatments of the most common sexually transmitted diseases.27-7Introduction Male and female reproductive systems Function together to produce offspring Female reproductive system nurtures developing offspring Produce important hormones 27-8Male Reproductive System TestesPrimary organsDevelop in the abdominal pelvic cavity of fetusDescend into scrotal sac shortly before or after birthProduce the male sex cells (sperm) Produce the male hormone testosteroneScrotum – sac that holds the testesSeminiferous tubulesOn top of testesFilled with spermatogenic cells that produce sperm cellsInterstitial cells produce testosteroneMale System27-9Male Reproductive SystemBackName the structures that are unique to the male reproductive system.27-10Spermatogenesis Spermatogonia (46 chromosomes)Mitosis – makes primary spermatocytesUndergo meiosis  two secondary spermatocytes Divides – two spermatids = 4 spermatidsDevelop flagella to become mature sperm cells with 23 chromosomesSpermatogenesis27-11Sperm CellsHeadNucleus with 23 chromosomesAcrosome – enzyme-filled sac Helps sperm penetrate ovumMidpieceMitochrondria that generate cell’s energyTailFlagellum that propels sperm forward27-12Back27-13Male Internal Accessory OrgansEpididymis Sits on top of each testisReceives spermatids from seminiferous tubulesSpermatids become sperm cellsVas deferensTube connected to epididymisCarries sperm cells to urethraSeminal vesicleSecreteFluid rich in sugar used to make energyProstaglandins – stimulate muscular contractions in female to propel sperm forwardSeminal fluid Released into vas deferens just before ejaculation60% of semen volumeMale System27-14Male Internal Accessory Organs (cont.) Prostate gland Surrounds urethraProduces and secretes a milky, alkaline fluid into urethra just before ejaculationFluid protects sperm in the acidic environment of the vagina40% of semenBulbourethral (Cowper’s) glandsProduce a mucus-like fluidSecreted just before ejaculationLubricates end of penisSemenAlkaline mixtureNutrientsProstoglandins1.5 to 5.0 ml per ejaculateSperm count of 40 to 250 million/mLMale System27-15Male External Accessory OrgansScrotumHolds testes away from bodyTemperature 1° below body temperatureLined with serous membrane that secrets fluidTestes move freelyPenisShaft Erectile tissues surround urethraGlans penisCone-shaped structure on end of penisPrepuce Skin covering glans penis in uncircumcised malesFunctionsDeliver spermUrinationMale System27-16Erection, Orgasm, and Ejaculation ErectionParasympathetic nervous system stimulates erectile tissue Becomes engorged with bloodOrgasmSperm cells propelled out of testes into urethraSecretions from accessory organs also released into urethraEjaculationSemen is forced out of urethraSympathetic nerves then stimulate erectile tissue to release blood Penis returns to flaccid state27-17Male Reproductive HormonesHypothalamusGonadotropin-releasing hormone (GnRH) Stimulates anterior pituitary to releaseFollicle-stimulating hormone (FSH) – initiates spermatogenesisLuteinizing hormone (LH) – stimulates interstitial cells in the testes to produce testosteroneTestosteroneSecondary sex characteristicsMaturation of male reproductive organsRegulated by negative feedback27-18Apply Your KnowledgeMatching: ___ Vasectomy A. Spermatogenesis___ Mixture of sperm and fluids B. Testes___ Sperm cell formation C. Penis___ Secrete alkaline fluid/prostaglandins D. Vas deferens___ Produce testosterone E. Hypothalamus___ GnRH F. Semen___ Erectile tissue G. Seminal vesicleGEFACBDANSWER:Correct!27-19Diseases and Disorders of the Male Reproductive SystemDisease/DisorderDescriptionBenign prostatic hypertrophy (BPH)Nonmalignant enlargement of the prostate gland; common in older menEpididymitisInflammation of an epididymis; usually starts as an urinary tract infectionImpotence or erectile dysfunction (ED)Disorder in which erection cannot be achieved or maintained; about 50% of males between 40 and 70 have some degree of ED27-20Diseases and Disorders of the Male Reproductive SystemDisease/DisorderDescriptionProstate cancerMost common form of cancer in men over 40; risks of developing it increase with ageProstatitisInflammation of the prostate gland; may be acute or chronicTesticular cancerMalignant growth in one or both testicles; more common in males 15–30 years; more aggressive malignancy27-21Apply Your KnowledgeYour patient has an elevated PSA. What is a PSA and what does it indicate?ANSWER: The PSA is a prostate-specific antigen in the blood. Elevations of the PSA may indicate prostate cancer.Bravo!27-22Female Reproductive SystemOvaries (2)Primary sex organs produceSex cells called ovaHormones estrogen and progesterone Located in the pelvic cavity Medulla Inner area; contains nerves, lymphatic vessels, and blood vesselsCortexOuter area; contains ovarian follicles Covered by epithelial and dense connective tissuesFemale System27-23Female Reproductive SystemBackName the structures that are unique to the female reproductive system.27-24Ovum Formation (cont.)Primordial follicles develop before birth and containA primary oocyte or immature ovum (born with maximum number)Follicular cellsOogenesis is the process of ovum formationAt puberty, primary oocytes are stimulated to continue meiosisBecomes 1 polar body (a nonfunctional cell) and A secondary oocyteSecondary oocyte released during ovulationIf fertilized, the oocyte divides to form a mature, fertilized ovum27-25Female Internal Accessory OrgansFallopian tube – oviductInfundibulum and fimbriaeFringed, expanded end of fallopian tube near ovaryFunction to “catch” an ovum Muscular tube Lined with mucous membrane and ciliaPropels ovum toward uterusInternal Accessory Organs27-26Female Internal Accessory Organs (cont.)UterusHollow, muscular organReceives embryo and sustains its developmentDivisionsFundus – domed upper portionBody – main portionCervix – narrow, lower section extending into vagina (cervical orifice)Wall of uterusEndometriumInnermost liningVascularTubular glands – mucusMyometrium Middle, thick, muscular layerPerimetriumThin layer covering the myometriumSecretes serous fluid to coat and protect uterusInternal Accessory Organs27-27Female Internal Accessory Organs (cont.)VaginaTubular, muscular organExtends from uterus to outside body (vaginal introitus)Muscular folds – rugae – enable expansionReceive erect penisPassage for delivery of offspring and uterine secretionsWallInnermost mucosal layerMiddle muscular layerOuter fibrous layerInternal Accessory Organs27-28Internal Female OrgansBack27-29External Accessory Organs Mammary glandsSecretion of milkStructuresNippleOxytocin induces lactiferous ducts to deliver milk through openingsAreola – pigmented area around nippleAlveolar glands – within mammary glands Make milk when stimulated by prolactin27-30External GenitaliaCollectively known as the vulvaLabia majoraRounded folds of adipose tissue and skinProtect other external reproductive organsLabia minoraFolds of skin between labia majoraVery vascularMerge to form hood over clitorisVestibule – space enclosed by labia minoraBartholin’s glands secrete mucus during sexual arousalExternal Genitalia27-31External Genitalia (cont.)ClitorisAnterior to urethral meatusContains female erectile tissueRich in sensory nervesPerineumBetween vagina and anusArea for episiotomy, if needed, during birth processExternal Genitalia27-32Erection, Lubrication, and Orgasm Nervous stimulation Clitoris becomes erect Bartholin’s glands activate – lubricationVagina elongatesOrgasmSufficient stimulation of clitorisWalls of uterus and fallopian tubes contract to propel sperm up tubes27-33Female Reproductive HormonesHypothalamus secretes GnRHGnRHAnterior pituitary releases FSH & LHStimulatesOvaries to produceestrogen and progesteroneEstrogen and progesterone Responsible for development of secondary sex characteristics27-34Reproductive CycleMenstrual cycleRegular changes in uterine lining, resulting in monthly bleedingMenarche – first menstrual period Menopause – termination of cycle due to normal aging of ovaries27-35Follicular cellsbecomecorpus luteum,which secretesprogesteroneAnterior pituitaryreleases FSHUterine lining thickensOvarian folliclematures and secretesestrogenThen releases LHTriggers ovulationLining more vascular and glandularWithout fertilization Corpus luteum degenerates Estrogen and progesterone  levels fall Uterine lining breaks down – menses starts Cycle begins again with release of FSHReproductive Cycle (cont.)27-36Apply Your KnowledgeTrue or False: ___ The ovaries only produce estrogen.___ Ovulation is the process of ovum formation.___ The fallopian tube is also called the oviduct.___ The endometrium is the outer layer of the uterine wall.___ Alveolar glands produce milk.___Oxytocin induces the alveolar glands to deliver milk through the nipples.___ Menarche is the termination of the menstrual cycle.___ Menopause occurs due to normal aging of the ovaries.FTFTFFTFANSWER:firstlactiferous ductsinner layerOogenesis produce estrogen and progesteroneYIPPEE!27-37Diseases and Disorders of the Female Reproductive SystemDisease/DisorderDescriptionBreast cancerSecond leading cause of cancer deaths in women; classified as stage 0 to 4Cervical cancerSlow to develop; Pap smear detects abnormal cervical cellsCervicitisInflammation of the cervix usually due to an infectionDysmenorrheaCondition with severe menstrual cramps that limit normal activities27-38Diseases and Disorders of the Female Reproductive System (cont.)Disease/DisorderDescriptionEndometriosisTissues of uterine lining growing outside of the uterusFibrocystic breast diseaseAbnormal cystic tissue in the breast; size varies related to menstrual cycle; common in 60% of women between 30 and 50FibroidsBenign tumors in the uterine wall; affect 25% of women in their 30s and 40sOvarian cancerConsidered more deadly than other types; detection difficult and often spreads before detection27-39Diseases and Disorders of the Female Reproductive System (cont.)Disease/DisorderDescriptionPremenstrual syndrome (PMS)Collection of symptoms occurring just before a menstrual periodVaginitis/ vulvovaginitisInflammation of the vagina/inflammation of vagina and vulva; both associated with abnormal vaginal dischargeUterine (endometrial) cancerMost common in post-menopausal women; causes about 6% of cancer deaths in women27-40Apply Your KnowledgeMatching: ___ Inflammation of the cervix A. Dysmenorrhea___ Cancer common in post-menopausal women B. Cervical cancer___ Develops slowly; detected by Pap smear C. Fibroids___ Uterine tissue grows outside uterus D. Breast cancer___ Second leading cause of cancer death in women E. Cervicitis___ Severe menstrual cramps F. Endometriosis___ Benign tumors in the uterine wall G. Uterine cancerGFDCBAEANSWER:GoodJob!27-41PregnancyPregnancy – condition of having a developing offspring in the uterusFertilization – process in which a sperm cell unites with an ovum; results in pregnancyOnly one sperm cell penetrates the follicular cells and the zona pellucida that surround the ovum’s cell membraneAfter fertilization, ovum releases enzymes that cause the zona pellucida to become impenetrable to other spermZygote forms from union of ovum and sperm Contains 46 chromosomes27-42The Prenatal PeriodTime before birthZygote – undergoes rapid mitosisFirst week after fertilizationCleavage – rapid cell divisionMorula – ball of cells resulting from cleavageTravels down fallopian tube to uterusBecomes blastocyst, which implants in endometrial wall BlastocystSome cells (inner cell mass) become embryoOthers, along with cells from uterus, form placenta27-43The Prenatal Period (cont.)Embryonic period Week 2 through 8Inner cell mass organizes into three primary germ layersEctodermMesodermEndodermFormation of Placenta Amnion Umbilical cord Yolk sack Most internal organs and external structures of embryo27-44The Prenatal Period (cont.)Last 3 months – fetal brain cells rapidly divideGI and respiratory systems last to develop Fetal periodWeek 8 through birthRapid growth5th month – skeletal muscles active6th month – gains weight27-45Fetal CirculationPlacenta and umbilical blood vessels carry out the exchange of nutrients, oxygen, and waste productsUnique differences from normal circulationForamen ovale – hole between right and left atria enables most of fetal blood to bypass lungsDuctus arteriosus – connection between pulmonary trunk and aortaDuctus venosus – vessel that bypasses liver27-46Hormonal Changes During PregnancyEmbryonic cells secrete human chorionic gonadotropin (HCG)Maintains the corpus luteumEstrogen and progesteroneSecreted by corpus luteum and placentaFunctions Stimulate uterine lining to thicken, development of mammary glands, enlargement of female reproductive organsInhibit release of FSH and LH from anterior pituitary gland (preventing ovulation) and uterine contractions27-47Hormonal Changes (cont.)Relaxin From corpus luteumInhibits uterine contractions and relaxes ligaments of pelvisLactogen From placentaStimulates enlargements of mammary glandsAldosterone From adrenal glandIncreases sodium and water retentionParathyroid hormone (PTH)Helps maintain high calcium levels in the blood27-48Apply Your KnowledgeWhat are the primary germ layers and what tissue develops from them?ANSWER: The primary germ layers are the: Ectoderm – nervous tissue and some epithelial tissue Mesoderm – connective tissue and some epithelial tissue Endoderm – epithelial tissue onlyRight!27-49The Birth ProcessBegins when progesterone levels fallProstaglandins secreted by uterus stimulate uterine contractionsUterine contractions stimulate posterior pituitary gland to release oxytocinOxytocin stimulates strong uterine contractions 27-50The Birth Process (cont.)Three stagesDilation Cervix thins and softens (effacement)Lasts 8 – 24 hoursExpulsion or parturition Actual birthMay take 30 minutes or lessPlacental stage – 10 to 15 minutes after the birth, the placenta separates from uterine wall and is expelled27-51The Birth Process (cont.)The postnatal periodSix-week period following birthNeonatal period – first four weeksNeonate is adjusting to life outside uterusMilk production and secretionProlactin – production of milkOxytocin – ejection of milk from mammary gland ductsProduction continues as long as breast-feeding continues27-52Apply Your KnowledgeWhat are the three stages of the birth process and what occurs during each?ANSWER: The three stages are: Dilation – the cervix thins, softens (effacement), and dilates to approximately 10 cmExpulsion – also called parturition; the actual birth stagePlacental stage – placenta separates from uterine wall and is expelledImpressive!27-53Contraception MethodDescriptionCoitus interruptusPenis is withdrawn from vagina before ejaculation; not a reliable methodRhythm methodRequires abstinence around time of ovulation; not a reliable methodMechanical barriersPrevent sperm from entering female reproductive tractChemical barriersDestroy sperm in the female reproductive tract; primarily spermicides; often used with mechanical barriers27-54Contraception (cont.)MethodDescriptionOral contraceptivesBirth control pills; prevent ovulation by preventing LH surgeInjectable contraceptivesPrevent ovulation and alter lining of uterus to prevent implantation of blastocystInsertable contraceptivesRing inserted vaginally and removed at the beginning of the 4th week to allow menstruationContraceptive implantsSmall rods of progesterone implanted beneath skin; prevent ovulation27-55Contraception (cont.)MethodDescriptionTransdermal contraceptivesContraceptives in the form of a patch; applied weekly for 3 weeks; not used the 4th week to allow menstruationIntrauterine device (IUD)Small, solid devices placed into uterus by MD; prevents implantation of blastocystSurgical methodsTubal ligation – fallopian tube fulgurated to prevent sperm from reaching oocyteVasectomy – vas deferens is fulgurated to prevent ejaculation of sperm27-56Apply Your KnowledgeANSWER: The rhythm method is not as effective as other birth control, because it is sometimes difficult to tell when ovulation occurs.Your patient has just been told that she is pregnant, but she does not understand why she could get pregnant. She states, “ I have been using the rhythm method of birth control very carefully.” What patient teaching would you do to assist her to understand?Good Answer!27-57InfertilityInability to conceive a childPrimary – no prior pregnancy, unable to achieve pregnancy in 12 monthsSecondary – at least one prior pregnancy, unable to achieve pregnancy after one yearCauses 15% unknown35% male-related problems50% female-related problems27-58Infertility (cont.)Male-relatedImpotenceRetrograde ejaculationLow or absent sperm countMedications/drugsDecreased testosteroneScarring from STDsPrior mumps infection Inflammation of epididymis or testesFemale-relatedScarring from STDsPelvic inflammatory diseaseInadequate dietNo ovulation or menstrual cycleEndometriosisAbnormal shape of uterus or cervixHormonal imbalancesCysts in ovariesOlder than 40 years 27-59Infertility (cont.)Tests Semen analysisMonitoring of morning body temperatureBlood hormone measurementsEndometrial biopsyUrine analysis for LHHysterosalpingogram LaparoscopyTreatmentsSurgical repair of abnormalitiesFertility drugsHormone therapiesArtificial inseminationIn vitro fertilization Use of surrogate27-60Apply Your Knowledge___ Retrograde ejaculation___ Mumps infection___ Inadequate diet___ Scarring from STDs___ Pelvic inflammatory  disease___ Hormone imbalances___ Use of some medications ___ Being over 40 years oldIndicate whether each cause of infertility is male-related (M), female-related (F), or both (B).BFFFFMMMANSWER:Very good!27-61Sexually Transmitted DiseasesSTDCause AIDSHIV virus causes AIDS; described in Chapter 21ChlamydiaCaused by bacterium; most commonly reported; often no symptoms in female Genital wartsCaused by HPV; not everyone infected has symptomsGonorrhea Bacterial cause27-62Sexually Transmitted Diseases (cont.)STDCause Herpes simplexCaused by viruses; type I causes cold sores; type II commonly known as genital herpes; may be passed from mother to child during childbirthPubic liceParasitic infestation; commonly called crabsSyphilisCaused by bacteria; decreasing in women but increasing in males who have sex with other malesTrichomoniasisCaused by protozoan parasite; also called trichomonas infection or “trich”27-63Apply Your KnowledgeMatch:___ Most commonly reported STD in the U.S. A. Gonorrhea___ Two types; both caused by a virus B. Genital warts___ Crabs C. Syphilis___ Increasing incidence in males D. Chlamydia___ Common bacterial STD; can also grow in mouth E. Pubic lice___ Caused by HPV virus F. Herpes simplex FECABDANSWER:SUPER!27-64In Summary27.1 The organs of the male reproductive system include the testes, responsible for sperm and hormone production, and the accessory organs of vas deferens, seminal vesicles, prostate and bulbourethral glands, scrotum, and penis.27.2 Spermatogenesis begins in the seminiferous tubules of the testes. They mature in the epididymis first as spermatogonia, then as spermatocytes, and finally as spermatids.27-65In Summary (cont.)27.3 Semen is a mixture of seminal fluid, prostatic fluid, sperm cells, and lubricating bulbourethral fluid.27.4 Erection occurs during sexual arousal, causing penile engorgement with blood. Ejaculation occurs when semen and its sperm cells are forced out of the body through the urethra.27.5 Testosterone is responsible for the male secondary sex characteristics and maturation of the male reproductive organs.27-66In Summary (cont.)27.6 The diseases of the male reproductive system vary widely between simple inflammation and cancers. The more common diseases and disorders, with their varied symptoms and treatments, are outlined in the Pathophysiology section of this chapter, immediately following the A&P of the male reproductive system.27.7 The organs of the female reproductive system include the ovaries, fallopian tubes, uterus, and vagina. The external accessory organs include the mons pubis, labia majora and minora, clitoris, urethral meatus, vaginal orifice, Bartholin’s glands, perineum, and mammary glands.27-67In Summary (cont.)27.8 Ova originate from the primordial follicles within the ovaries present during fetal development, which produce the oocyte and follicular cells responsible for oogenesis.27.9 Estrogen is responsible for female secondary sex characteristics. Both estrogen and progesterone stimulate the uterine lining to thicken in preparation for pregnancy and inhibit uterine contractions during pregnancy.27.10 Ovulation occurs when the anterior pituitary releases a surge of LH, causing the release of a mature ovum.27-68In Summary (cont.)27.11 The follicular cells become the corpus luteum, which releases more progesterone, which causes the uterine lining to become more vascular and glandular to prepare for the pregnancy.27.12 The female menstrual cycle causes periodic changes in the uterine lining. After a menstrual period, the body prepares for the next ovulatory cycle with increasing levels of estrogen and progesterone. If pregnancy does not occur, these levels drop, causing the uterine lining to break down and resulting in the next menstrual period.27-69In Summary (cont.)27.13 Menopause is the cessation of the menstrual cycle related to normal aging of the ovaries.27.14 The diseases of the female reproductive system vary widely between simple inflammation and cancers. The more common diseases and disorders, with their varied symptoms and treatments, are outlined in the Pathophysiology section of this chapter, immediately following the A&P of the female reproductive system.27-70In Summary (cont.)27.15 Fertilization occurs with the union of a sperm cell and ovum; usually occurs within the fallopian tubes, but may occur anywhere in the female reproductive tract. 27.16 The fertilized ovum, now a blastocyst, implants in the endometrial wall of the uterus.27.17 The embryonic period occurs from week 28 of the pregnancy, and the fetal period is from week 9 through delivery.27-71In Summary (cont.)27.18 Hormonal changes stimulate the uterine lining and inhibit FSH and LH production to prevent ovulation. Mammary glands are stimulated and enlarged, uterine contractions are inhibited, and the pelvic ligaments loosen in preparation for delivery.27.19 Some of the contraceptive methods include coitus interruptus; barrier methods; chemical barriers; oral contraceptives; injectable, implantable and insertable contraceptives; and intrauterine devices. Their mechanisms are discussed in detail within the chapter.27-72In Summary (cont.)27.20 The causes of infertility are varied, with about 15% of infertility for unknown causes. A number of infertility tests and treatments are discussed within the chapter.27.21 There are many sexually transmitted diseases, all passed between sexual partners (heterosexual and same-sex partners alike). Their symptoms, treatments, and sequelae for both sexes are discussed in detail in the Pathophysiology section devoted to STDs at the end of this chapter.27-73The reproduction of mankind is a great marvel and mystery. ~Martin LutherEnd of Chapter 27