ReproductionReproduction andand DevelopmentDevelopment ““ChapterChapter 1616”” GeneralGeneral OutcomesOutcomes In this Unit, You will … Explain how survival of the human species is ensured through reproduction. Explain how human reproduction is regulated by chemical control. Explain how cell differentiation and development in the human organism are regulated by a combination of genetic, endocrine, and environmental factors. CurriculumCurriculum OutcomesOutcomes KeyKey TermsTerms CartoonCartoon FemaleFemale SexSex OrgansOrgans MaleMale SexSex OrgansOrgans QuestionsQuestions QuestionsQuestions 11-- 44 pagepage 510510 TheThe ImportanceImportance ofof ReproductionReproduction Ensure the survival of a species Sexual reproduction involving the fusion of male and female sex cells creates new gene combinations. Diversity produced by new gene combinations provides a basis for natural selection: best adapted survive. The human reproductive system involves separate male and female reproductive systems. Male gonads “testes” produce male sex hormone called sperm. Female gonads “ovaries” produce eggs. The fusion of male and female sex cells is called fertilization, produces a zygote. Zygotes divide many times to produce an embryo, which develops into a fetus. EggEgg andand SpermSperm ActivityActivity TheThe MaleMale ReproductiveReproductive SystemSystem MaleMale ReproductiveReproductive SystemSystem Human male and female sex organs originate in the same area of the body: adnominal cavity. During last two months of fetal development, the testes descend through a canal into the scrotum – a pouch of skin located below the pelvic region. A thin membrane forms over the canal to prevent the testes from reentering the abdominal cavity. Temperature in the scrotum few degrees color than abdominal cavity. Sperm will not develop at body temp. If testes do not descend the male will be sterile. Vas deferens – tube that conducts sperm towards the urethra. Ejaculatory duct – a tubule formed at the union of vasa deferentia and seminal vesicle ducts and opening into the urethra. (propels movement of sperm and fluids called semen into the urethra) Urethra, also serves as a channel for urine. A sphincter regulates the voiding of urine from the bladder. Never open at the same time. Any blockage of the vas deferens prevents movement of sperm from testes to environment. A surgical procedure, in which vas deferens are cut and tied, is called a vasectomy VasectomyVasectomy During sexual excitement, erectile tissue fills with blood. Stimulation of parasympathetic nerve causes arteries in penis to dilate (increase blood flow) As blood moves into the penis, the sinuses swell, compresses the veins which carry blood away from the penis. Any damage to the parasympathetic nerve can cause impotency (penis fails to become erect) QuestionsQuestions QuestionsQuestions 11--22 pagepage 514514 SpermatogenesisSpermatogenesis Inside of each testis is 5 cm long Filled with twisted tubes called seminiferous tubules (250m) Seminiferous tubules are the site of spermatogenesis – formation of sperm cells. Tubules are lined with sperm producing cells call spermatogonia. During spermatogenesis, spermatogonia divide to form spermacytes. Spermacytes then differentiate into spermatids, which are immature sperm cells. (23 chromosomes) Take 9-10 weeks for spermacytes to differentiate into sperm cells. Specialized cells in the seminiferous tubules, called sertoli cells, nourish the developing sperm cells until they mature. Sperm are produced in the testes, but mature in the epididymis, a compact coiled tube attached to the outer edge of the testis. Sperm is built for motion, streamlined with only a small amount of cytoplasm surrounding the nucleus. An acrosome, caps the head of the sperm cell. Filled with a specialized enzymes that dissolves the gelatinous layer surrounding the egg. (allows sperm to penetrate the cell layer surrounding the egg) DevelopmentDevelopment ofof SpermSperm insideinside thethe SeminiferousSeminiferous TubulesTubules HumanHuman SpermSperm CellCell QuestionsQuestions QuestionsQuestions 33--55 pagepage 515515 -- 516516 ActivityActivity SeminalSeminal FluidFluid Sperm leave the body in a fluid called semen. (provides a swimming medium) Ejaculation in which sperm leave the male body via penis. The vasa deferentia, seminal vesicles, ejaculatory duct and prostate gland contract, forcing semen to the end of the penis. Every ejaculation 3 and 4 mL of fluid containing 500 million sperm are released. Seminal fluids ( fluid part of semen) are secreted by three glands along the vasa deferentia and ejaculatory duct. Fluids from the seminal vesicules contain fructose and prostaglandis. Fructose – source of energy for sperm. Prostaglandins – act as a chemical signal in the female system, triggering rhythmic contraction of smooth muscle along the reproductive tract. (assists sperm movement) Prostate gland – secretes an alkaline buffer that protects the sperm against the acidic environment of the vagina. Cowper’s (bulbourethral) glands – secrete a mucus rich fluids prior to ejaculation. (protect sperm from acids from the urethra associated with passage of urine. At body temp. sperms cells live 24-72 hours. Stored at -100 degrees Celsius the remain viable for years. ReviewReview ofof MaleMale ReproductiveReproductive SystemSystem HormoneHormone controlcontrol ofof thethe MaleMale ReproductiveReproductive SystemSystem PrimaryPrimary sexualsexual characteristicscharacteristics –– physicalphysical characteristicscharacteristics thatthat areare directlydirectly involvedinvolved inin reproductionreproduction (refer(refer toto tabletable onon lastlast slide)slide) SecondarySecondary sexualsexual characteristicscharacteristics –– externalexternal featuresfeatures ofof anan organismorganism thatthat areare indicativeindicative ofof itsits gender,gender, butbut areare notnot thethe reproductivereproductive organs.organs. SecondarySecondary SexualSexual CharacteristicsCharacteristics Testosterone – male sex hormone produced by the interstitial cells of the testes. (found between the seminiferous tubules) Stimulates the maturation of the testes and the penis and spermatogenesis. Promotes development of facial + body hair; growth of the larynx; increases secretion of body oils (causes acne). Associated with sex drive and aggressive behaviour. SecondarySecondary SexualSexual CharacteristicsCharacteristics HypothalamusHypothalamus ++ pituitarypituitary controlcontrol thethe productionproduction ofof spermsperm andand malemale sexsex hormonehormone inin thethe testes.testes. PituitaryPituitary producesproduces gonadotrophicgonadotrophic hormoneshormones thatthat regulateregulate functionsfunctions ofof thethe testes.testes. FollicleFollicle –– stimulatingstimulating hormonehormone stimulatesstimulates thethe productionproduction ofof sperm.sperm. LuteinizingLuteinizing hormonehormone promotespromotes thethe productionproduction ofof testosterone.testosterone. HypothalamusHypothalamus secretessecretes gonadotrophingonadotrophin –– releasingreleasing hormonehormone atat pubertypuberty whenwhen testosteronetestosterone levelslevels areare low.low. ItIt activatesactivates thethe pituitarypituitary toto secretesecrete FSHFSH andand LH.LH. FSHFSH actsacts directlydirectly onon thethe spermsperm producingproducing cells.cells. LHLH stimulatesstimulates testosteronetestosterone production.production. MaleMale ReproductiveReproductive HormonesHormones SummarySummary ActivityActivity QuestionsQuestions QuestionsQuestions 11--77 pagepage 519519 DrawDraw aa diagramdiagram ofof thethe MaleMale ReproductiveReproductive System.System. LabelLabel allall partsparts andand explainexplain whatwhat eacheach does.does. BeBe suresure toto explainexplain thethe rolerole eacheach hormonehormone plays.plays. TheThe FemaleFemale ReproductiveReproductive SystemSystem More complicated then males. Males continually produce sperm. Women ovum matures every month. As with males, female secondary sexual characteristics develop at puberty as a result of hormonal stimulation. Develop breasts, widening of hips, hair growth in arm pits, pubis. Some women these changes can take a decade, other it can be very quick, within a year or two. Much of the development is determined by heredity. FemaleFemale ReproductiveReproductive AnatomyAnatomy FemaleFemale ReproductiveReproductive AnatomyAnatomy SecondarySecondary SexualSexual CharacteristicsCharacteristics inin FemalesFemales During fetal development in females, paired ovaries form in the same abdominal region as the testes in the male. Like the testes, the ovaries descend, however they remain in the pelvic region. At birth, oocytes (immature ova) are already present in the ovary. Uterus (womb) – largest organ in females reproductive system. Muscular, hollow organ shaped like and invert pear. Embryo and fetus develop in the uterus. Uterus is composed of two tissues: muscular outer lining, glandular inner lining known as the endometrium. Ovaries connected to uterus by two fallopian tubes (oviduct). At the ends of the fallopian tubes are fingerlike projections called fimbria. The uterus is connected to the outer environment by the vagina. Sexual intercourse occurs within the vagina, it is also the birth canal. Vagina is very acidic Cervix – a muscular ring that separates the vagina from the uterus. Cancer of the cervix is a major form of cancer in females. Early detection with a Pap test improves chances. Note:Note: thethe urethraurethra (tube(tube whichwhich urineurine exits)exits) isis