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 notnot connectedconnected toto reproductivereproductive organsorgans inin females.females.
UrethraUrethra inin malesmales isis muchmuch longerlonger thanthan females,females, thisthis accountsaccounts forfor thethe factfact thatthat femalesfemales areare moremore proneprone toto bladderbladder infections.infections. OogenesisOogenesis andand OvulationOvulation
OvumOvum muchmuch largerlarger thanthan sperm.sperm.
OvumOvum isis packedpacked withwith nutrients.nutrients.
UsuallyUsually onon oneone ovumovum producedproduced atat aa time.time.
OvumOvum hashas 2323 chromosomeschromosomes Oogenesis – the formation of an ovum. Occurs in the ovaries called follicles.
A follicle contains two types of cells: a primary oocyte and cells of granulosa.
The granulosa is the layer of cells that form the follicle wall. (provides nutrients)
Oogenesis begins when nutrient follicle cells surrounding the primary oocyte begin to divide.
Cytoplasm and nutrients move OogenesisOogenesis Oogenesis begins when nutrient follicle cells surrounding the primary oocyte begin to divide.
Cytoplasm and nutrients move to one pole to form secondary oocyte.
Secondary oocyte contains 23 chromosomes.
A fluid filled cavity forms.
Ovulation – release of the secondary oocyte from the follicle held within the ovary.
The surrounding follicle cells remain within the ovary and are transformed into the corpus luteum, which secretes hormones essential for pregnancy.
If a pregnancy does not occur, the corpus luteum degenerates after about 10 days. Upon it release from the ovary, the secondary oocyte is swept into a funnel shaped end of the fallopian tube by the fimbria.
The secondary oocyte is moved along the fallopian tube by cilia, where if healthy sperm are present it will become fertilized.
Will undergo unequal division of cytoplasm and nutrients and develop into a fertilized ovum
If it is not fertilized it will deteriorate within 24 hours and die.
A women will then undergo menstrual cycle. ProcessProcess ofof OvulationOvulation QuestionsQuestions
QuestionsQuestions 11--22 pagepage 522522 ActivityActivity CaseCase StudyStudy MenstrualMenstrual CycleCycle PubertyPuberty alsoalso initiatesinitiates thethe menstrualmenstrual cycle.cycle.
LastsLasts andand averageaverage ofof 2828 days.days.
RegulatedRegulated byby hormones.hormones.
CanCan bebe divideddivided intointo fourfour phases:phases: 1)1) flowflow phasephase 2)2) follicularfollicular phasephase 3)3) ovulatoryovulatory phasephase 4)4) lutealluteal phasephase FourFour PhasesPhases
Menstration (flow phase) – shedding of the endometrium (5 days)
Follicular phase – the development of follicles in the ovary. (estrogen secreted) (6-13 days)
Ovulatory Phase – secondary oocyte brusts from the ovary and follicular cells differentiate into corpus luteum.
Luteal Phase – estrogen levels decline, progesterone is secreted (prepares uterus) (15-28 days) FourFour PhasesPhases ofof thethe MenstrualMenstrual CycleCycle FourFour PhasesPhases The female ovaries undergo decline after the onset of puberty.
Each of the two ovaries contain 400 000 follicles at puberty.
Many of the follicles die.
Between the ages of about 12 – 50, approx 400 eggs will mature. menopause (when ovulation ceases, few follicles remain)
Higher incidence of genetic defects in children are produced by older women (linked to age of follicles) FeedbackFeedback ControlControl ofof thethe MenstrualMenstrual CycleCycle Hypothalamus – pituitary regulates the production of estrogen and progesterone.
The gonadotrophins follicle- stimulating horomone (FSH) and lutenizing hormone (LH) regulate the control of hormones produced by the ovaries
Puberty is signalled by the release of GnRH from the hypothalamus.
GnRH activates the pituitary gland which is in production and storage of FSH and LH.
Follicular phase, the blood carries FSH to the ovary (follicular devep. Occurs)
The follicles secrete estrogen which initiates development of endometrium
As estrogen levels rise a neg. feedback is sent to pituitary to turn off secretions of FSH
FemaleFemale ReproductiveReproductive HormonesHormones SummarySummary
HomeoworkHomeowork
ReviewReview QuestionsQuestions (old(old text)text) PagePage 418418 QuestionsQuestions 99-- 2020
QuestionsQuestions 33--44 pagepage 526526
DrawDraw aa diagramdiagram ofof thethe femalefemale reproductivereproductive system.system. LabelLabel allall partsparts andand bebe ableable toto explainexplain whatwhat eacheach doesdoes andand whatwhat rolerole eacheach hormonehormone plays.plays. LABLAB Fertilization,Fertilization, Pregnancy,Pregnancy, andand BirthBirth Fertilization occurs in the fallopian tube.
23 chromosomes from sperm, 23 chromosomes from oocyte.
Of the 150 million – 300 million sperm, only a few hundred actually make it to the fallopian tubes.
Only a single sperm can fuse with the ovulated oocyte.
Take 3 – 5 days for the fertilized egg to travel 10 -12 cm down the fallopian tube to the uterus.
In this time it under goes many divisions in a process called cleavage. (no change in size) BlastocystBlastocyst –– anan earlyearly stagestage ofof embryoembryo development.development. (attaches(attaches toto uterusuterus wall).wall).
ImplantationImplantation –– thethe attachmentattachment ofof thethe embryoembryo toto thethe endometriumendometrium..
CleavageCleavage ChangesChanges InIn thethe FemaleFemale ReproductiveReproductive SystemSystem Fours days after fertilization, the zygote becomes and embryo.
After eight weeks it becomes a fetus.
Pregnancy takes place of nine months
For pregnancy to occur, menstruation will not occur.
LH levels remain high to maintain corpus luteum. The outer layer of the blastocyte gives rise to two structures: chorine and amnion
Chorine produces the hormone human chorionic gonadotrophic hormone, which maintains the corpus luteum for the first three months of pregnancy.
The functioning corpus luteum continues producing estrogen and progesterone.
Pregnancy tests identify hCG levels in the urine of women. Amniotic cavity – the fluid filled cavity surrounding the developing embryo. (insulates, protects from infection, dehydration, impact, temp)
Extra embryonic coelom – body cavity between the amnion and the chorine.
Yolk sac – a membranous sac that forms during embryo development (early red blood cell formation, digestive tract)
Placenta – the site for the exchange of nutrients and wastes between mother and fetus. (produces estrogen and progestrone – prevents another pregnancy)
Chorionic villi – vascular projections of the chorion.
Allantois – extraembryonic structure that contributes to the blood vessels of the placenta
Umbilical cord – structure that connects the fetus to the placenta. StructuresStructures thethe SupportSupport DevelopingDeveloping EmbryoEmbryo DevelopingDeveloping FetusFetus QuestionsQuestions
QuestionsQuestions 11 pagepage 532532 EmbryonicEmbryonic andand FetalFetal DevelopmentDevelopment Nine months of pregnancy is divided into three trimesters: 1) First trimester – extends from fertilization to end of the third month.
Gastrulation – process by which a gastrula is formed (two layered structure develops into a three layer structure)
Gastrulation begins when the disc elongates and forms a line of cells at the midline. Forms three layers: ectoderm, mesoderm, endoderm. (See table) GastrolationGastrolation By the end of the first month the 1cm long embryo is 500 times larger.
Many organs are beginning to develop
Four chambered heart has developed, brain is visible, limb buds with fingers and toes.
Ninth week embryo is a fetus
Arms and legs begin to move and a suckle reflex is evident. 2)2) SecondSecond trimestertrimester –– fourthfourth monthmonth toto endend ofof sixthsixth month.month.
FetusFetus isis aboutabout 88 cmcm long,long, allall organsorgans havehave formedformed (not(not fullyfully developed)developed)
FetusFetus willwill increaseincrease inin sizesize andand move.move. 3)3) ThirdThird trimestertrimester –– seventhseventh monthmonth untiluntil birth.birth.
BabyBaby growsgrows rapidly,rapidly, bodybody massmass increases,increases, organsorgans enlargeenlarge andand becomebecome developed.developed.
AtAt birthbirth thethe averageaverage infantinfant isis 5151 cmcm longlong andand aboutabout 3400kg3400kg StagesStages ofof DevelopmentDevelopment StagesStages ofof DevelopmentDevelopment EnvironmentalEnvironmental EffectsEffects onon DevelopmentDevelopment Health and lifestyle decisions of the mother remain with her child for a life time.
Proper nutrition
Spina bifida – spinal cord does not develop properly (result of low levels of folic acid)
Women who smoke have smaller babies.
Teatogens – medications, drugs, chemicals QuestionsQuestions
QuestionsQuestions 22--33 pagepage 536536 EffectsEffects ofof TeratogensTeratogens FetalFetal DevelopmentDevelopment
BirthBirth
266 days after implantation, uterine contractions signal the beginning of parturition (labour).
Cervix thins and dilates.
As amnion is forced in to the birth canal, it often bursts (water breaking)
Hormones play a vital role in the birthing process. Relaxin causes the ligaments within the pelvis to loosen and cervix to soften.
Decreased production of progesterone is crucial.
Oxytocin causes strong uterine contractions.
Labour can be induced using these hormones. BirthBirth LactationLactation
ElevatedElevated estrogenestrogen andand progesteroneprogesterone prepareprepare thethe breastsbreasts forfor milkmilk production.production.
EachEach breastbreast containscontains 2020 lobeslobes ofof glandularglandular tissue,tissue, eacheach suppliedsupplied withwith tinytiny ductsducts thatthat carrycarry fluidsfluids towardtoward thethe nipple.nipple.
ProlactinProlactin isis responsibleresponsible forfor stimulatingstimulating glandsglands withinwithin thethe breastbreast toto beginbegin producingproducing fluids.fluids.
AA womenwomen cancan produceproduce 1.51.5 LL ofof milkmilk aa day.day. LactationLactation SummarySummary QuestionsQuestions
QuestionsQuestions 11--66 pagepage 544544
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