2The Reproductive System Gonads – primary sex organsMale: testesFemale: ovariesGonads produce gametes and secrete hormonesMale gametes: spermFemale gametes: eggs (ova)Functions:Male: produce sperm and testosteroneFemale: produce eggs, estrogen and progesterone; nurture the developing embryo; and deliver the newborn baby.
5Testes Testes make sperm via meiosis Produce testosterone – male characteristicsEpididymis – collects mature sperm (mature for 20 days) and eventually propel them through the vas deferensVas deferens – tube where sperm travel to the outside of body (peristalsis)Urethra – urine and sperm leave through
6VasectomyVasectomy - the vas deferens is cut to prevent sperm leaving (and fertilizing an egg)
7Accessory Organs Seminal vesicles – produce 60% of semen Nourish sperm with fructose, Vitamin CProstate – secrete milky fluid to activate spermBulbourethral gland – secretes thick, clear mucusActs as lubricantProtects sperm vs. acidic environment found in urethra and vagina
8External male genitalia Scrotum – maintains testes at 3°C lower than bodyPenis – deliver spermShaftErectile tissue fills with bloodGlans penis – enlarged tipPrepuce – foreskin
9SpermProduction of sperm begins at puberty and continues throughout life in the testesDuring ejaculation, 2 to 5 ml of semen are released in which there are between million sperm per ml.Infertility results when there are less than 20 million per ml.
10Female Reproductive System MammariesOvariesDuct SystemFallopian tubesUterusVaginaExternal genitalia
14Female Internal Genitalia OvariesB:Fallopian tubes – receive oocyte and provide place for fertilizationC:Uterus – receives, retain, and nourishes eggD:Cervix – Bottom of uterusE:Vagina – thin walled tubeBirth canal – passageway for delivery of baby and menstrual flowReceives penis during copulationFemale Internal Genitalia
16Ovaries Where eggs are produced through meiosis Each ovary takes turns releasing one egg per month (twins = two eggs released)Secrete progesterone and estrogenEstrogen – secondary sex characteristics in femalesProgesterone – regulates menstruation
17Ovaries Consist of developing follicles Each follicle has: Oocyte (developing egg)Follicular cells (surround egg)Ovulation – when egg is mature the follicle ruptures releasing egg and follicle becomes corpus luteum
19Oogenesis Total supply of eggs are present at birth Ability to release eggs from puberty menopauseFSH causes some primary follicles to mature into oocytes every monthLH causes development of secondary follicleIf sperm penetrates oocyte then ovum is produced
20FertilizationSperm must travel to the egg and penetrate to combine the DNA from both parents -- this creates the first cell after fertilization: the Zygote23 chromosomes from each parent; zygote has a total of 46 chromosomes
21Fertilization normally occurs in the Fallopian Tubes Secondary oocyteOvulationUterusEndometriumUterine tubeBlastocyst cavityInner cell massTrophoblastZygote (fertilized egg)Early cleavage 4-cell stageEarly blastocystLate blastocyst (implanting)MorulaOvary(a)(b)(d)(e)(c)The fertilized egg (zygote) implants in the uterus
22OvaAn egg is usually a few days old before it implants in the uterus. At this point, it has already divided several times and is called a bastula.
23Female Cycles*Interesting fact – humans are one of the few animals that do not have some kind of visible obvious display of fertility.Evolutionary biologists suggest this trait evolved as a way to keep males interested for more than just the fertile period, increasing the likelihood of male parental care of offspring.
24Fluctuation of Gonadotropin Levels Figure 16.12a
25Fluctuation of Ovarian Hormone Levels Figure 16.12b
29How does a woman know she is pregnant? Missed periodChanges in body, tenderness in breasts, nausea…etcPregnancy test – tests urine for hormone levels (hCG – human chorionic gonadotropin) which is produced by the blastocyst 6-12 days after fertilization
36Development of the Human Fetus Table 16.1 (1 of 2)
37Development of the Human Fetus Table 16.1 (2 of 2)
38Initiation of Labor Figure 16.19, step 1 Baby moves deeper into mother’s birth canalFigure 16.19, step 1
39Initiation of Labor Figure 16.19, step 2 Pressoreceptors in cervix of uterus excitedBaby moves deeper into mother’s birth canalFigure 16.19, step 2
40Initiation of Labor Figure 16.19, step 3 Afferent impulses to hypothalamusPressoreceptors in cervix of uterus excitedBaby moves deeper into mother’s birth canalFigure 16.19, step 3
41Initiation of Labor Figure 16.19, step 4 Hypothalamus sends efferent impulses to posterior pituitary, where oxytocin is storedAfferent impulses to hypothalamusPressoreceptors in cervix of uterus excitedBaby moves deeper into mother’s birth canalFigure 16.19, step 4
42Initiation of Labor Figure 16.19, step 5 Hypothalamus sends efferent impulses to posterior pituitary, where oxytocin is storedPosterior pituitary releases oxytocin to blood; oxytocin targets mother’s uterine muscleAfferent impulses to hypothalamusPressoreceptors in cervix of uterus excitedBaby moves deeper into mother’s birth canalFigure 16.19, step 5
43Initiation of Labor Figure 16.19, step 6 Hypothalamus sends efferent impulses to posterior pituitary, where oxytocin is storedPosterior pituitary releases oxytocin to blood; oxytocin targets mother’s uterine muscleUterus responds by contracting more vigorouslyAfferent impulses to hypothalamusPressoreceptors in cervix of uterus excitedBaby moves deeper into mother’s birth canalPositive feedback mechanism continues to cycle until interrupted by birth of babyFigure 16.19, step 6
49Temporary methods of birth control What if you don’t want to have a baby?There are lots of options……Temporary methods of birth controlCondomBirth control pillsNuva-ringDepo-Provera (shot)IUD (semi-permanent)Diaphragm
51What about the morning after pill - also known as Plan B? Plan B must be taken within 72 hours of unprotected sex, it prevents the egg from releasing or the sperm from fertilizing the egg. It may also prevent implantation of a fertilized egg.Plan B does NOT work on women who are already pregnant.It can be bought from pharmacies, though some states have age restrictions.
52What about abortion?Regardless of your political views on the subject, abortion is legal in the U.S.Most procedures must be done early and involve removing the fetus from the uterus.