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SC BIOL 101 - Chapter 27

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Reproductive systemPrimary sex organs (gonads):Testes and ovariesProduce sex cells (gametes)Secrete steroid sex hormonesAndrogens (males)Estrogens and progesterone (females)Accessory reproductive organs: ducts, glands and external genitaliaMale reproductive anatomyScrotum: sac that contains the male gonads (testes); regulates gamete production in the testesSuperficial fasciaDartos muscles: smooth muscle that cause the skin of the scrotum to wrinkleCremaster muscle: the muscle that raises and lowers the testes within the scrotum; skeletal muscle not under voluntary control; regulate the temperature of the testes (testes at lower temperature for sperm production)EpididymisTestes: have multiple lobesSeminiferous tubule: where sperm is producedMyoid: muscle cells, job is to squeeze the seminifierous tubule to move spermLeydig: where testosterone is produced, immediately outside the seminiferous tubule; necessary for sperm productionSpermatogenic cells: produce spermInterstitial endocrine cells (leydig cells)Ductus (vas) deferensAmpalla of ductus deferens: sperm can be stored hereInguinal canal: testes drop through this canalUrethraProstate gland: contains the urethra and part of the vas deferensThe male duct system:Vasectomy: cutting and ligating the ductus deferens, which is a nearly 100% effective form of birth controlDuctus deferens: passes through the inguinal canal; propels sperm from the epididymis to the urethraUrethra: conveys both urine and semen; has three regions: prostatic urethra, membranous urethra, spongy (penile) urethraEjaculatory duct: where the ampulla of ductus deferens and seminal vesicle convergeAccessory glands: seminal vesiclesProduces viscous alkaline seminal fluidFructoseAscorbic acidCoagulating enzyme (vesiculase)Prostaglandins70% of the volume of semenduct of seminal vesicle joins the ductus deferens to form the ejaculatory ductProstateEncircle part of the urethraSecretes milky, slightly acid fluid:Contains citrate, enzymes, prostate-specific antigen (PSA)Plays a role in sperm activationMale reproductive anatomyBulbourethral glands (cowper’s glands)Prior to ejaculation, produce thick, clear mucusLubricates the glans penisNeutralizes traces of acidic urine in the urethraThe penisThe male copulatory organ4 structures:spongy urethracorpus spongiosum: surrounds the urethra, makes sure the urethra stays open so ejaculation can occurcorpora cavernosa x 2erection: erectile tissue fills with blood, causing the penis to enlarge and become rigidSemenMixture: sperm and accessory gland secretionsContents and functions:Nutrients: fructoseProtects and activates spermProstaglandins in semenDecrease the viscosity of mucus in the cervixStimulate reverse peristalsis in the uterusAlkaline: neutralizes the acid in the male urethra and female vaginaOnly 2-5 ml of semen are ejaculated, containing 20-150 million sperm/mlMale sexual responseErection:Parasympathetic reflex promotes release of nitric oxide (NO); potent vasodilator, erectile tissue becomes engorged (impotent men don’t produce enough NO)No causes vasodilationCorpora cavernosaCompresses drainage veinsCorpus spongiosum keeps urethra openImpotence: the inability to attain erectionEjaculation:Propulsion of semen from the male duct systemSympathetic spinal reflex causes:Ducts and accessory glands contractBladder sphincter muscle constrictsBulbospongiosus muscles to undergo a rapid series of contractionsSpermatogenesisSequence of events that produces sperm in the seminiferous tubules of the testesMost body cells are diploid and contain:2 sets of chromosomes; one maternal and one paternal23 pairs of homologous chromosomesgametes are haploid and contain:23 chromosomesMeiosisMeiosis and mitosis both require nuclear replication (DNA synthesis)Two rounds of division in meiosis and the result is haploid cellsMeiosis I: go through S phase and duplicate DNA; in metaphase (during mitosis all the chromosomes line up vertically at the center line and the chromosomes are pulled apart in meiosis: the chromosomes pair up and the chromosomes are pulled to each end)Daughter cells are diploid: 2 copies of every gene); first division does not produce identical daughter cellsDaughter cells undergo meiosis II with same phases; this time in metaphase all the chromosomes will align, spindles will separate chromosomes towards poles and 4 cells are ultimately produced with 23 chromosomes in each cellSpermatogenesisSpermatic cells give rise to spermSpermatagonium: stem cells, goes through mitosisSpermatic cells gives rise to sperm:MitosisMeiosisSpermatagenosisSubstentacular cellsLarge supporting cells (sertoli cells)Surround developing cellsNutrientsSignalsDispose of excess cytoplasm sloughedSecrete testicular fluid into lumen for transport of spermHypothalamic pituitary gonadal axisTestosterone production is under control by the hypothalamusGNRH, travels to anterior pituitary where it stimulates the secretion of two hormones: FSH and LHFSH: stimulates the follicles (spermatogenic cells of the semineforous tubes), antigen binding proteinTestosterone goes up GNRH goes downTestosterone is necessary for spermatogenesisInhibin produced when sperm count is high (when testosterone levels are high); negative feedback to inhibit GNRH and FHInternal and External female genitaliaOvaries and fallopian tubes of a femaleHeld in place by suspensory ligamentOvaryProduces eggs, releases one every other monthOvulation occurs, egg is released in area near the fibraeIf egg doesn’t reach fimbrae it is released into the body cavityIf fertilized and doesn’t reach the fallopian tube it is an eptopic pregnancyFertilization normally occurs in the ampulla and isthmusWomen are born with a fixed number of eggsHas a blood supply called the mesovarium; rich vascular supply to maintain the ovaOuter covering called germinal epitheliumFallopian tubeFimbriaeInfundibulumAmpullaIsthmus: narrow connection between the fallopian tube and the uterusUterusIsthmius is the connection between the ovaries and the uterusPerimetrium is the outerlayerMyometrium is the smooth muscle layer, thickest partEndometrium is the liningFundus is the upper portion where uterine tubes attachIsthmus is where the uterus meets the cervixCervix is the extension of the uterusProduces mucus; mucus plug here that prevents things from entering the uterusSex drive, intercourse reduces mucusMucus aids in lubricationVaginaMuscular tube made of smooth muscleWalls are collapsedLining of the vagina secretes


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