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The Reproductive System

The Reproductive System. A Practical Guide. The Reproductive System. Gonads – primary sex organs Male: testes Female: ovaries Gonads produce gametes and secrete hormones Male gametes: sperm Female gametes: eggs (ova) Functions: Male: produce sperm and testosterone

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The Reproductive System

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  1. The Reproductive System A Practical Guide

  2. The Reproductive System • Gonads – primary sex organs • Male: testes • Female: ovaries • Gonads produce gametes and secrete hormones • Male gametes: sperm • Female gametes: eggs (ova) • Functions: • Male: produce sperm and testosterone • Female: produce eggs, estrogen and progesterone; nurture the developing embryo; and deliver the newborn baby.

  3. Male Reproductive System • External genitalia: • Penis • Scrotum (house testes) • Accessory organs: • Seminal vesicles • Prostate • Bulbourethral gland • Duct system: • Epididymis • Vas deferens • Urethra

  4. Male Reproductive System

  5. Testes • Testes make sperm via meiosis • Produce testosterone – male characteristics • Epididymis – collects mature sperm (mature for 20 days) and eventually propel them through the vas deferens • Vas deferens – tube where sperm travel to the outside of body (peristalsis) • Urethra – urine and sperm leave through

  6. Vasectomy • Vasectomy - the vas deferens is cut to prevent sperm leaving (and fertilizing an egg)

  7. Accessory Organs • Seminal vesicles – produce 60% of semen • Nourish sperm with fructose, Vitamin C • Prostate – secrete milky fluid to activate sperm • Bulbourethral gland – secretes thick, clear mucus • Acts as lubricant • Protects sperm vs. acidic environment found in urethra and vagina

  8. External male genitalia • Scrotum – maintains testes at 3°C lower than body • Penis – deliver sperm • Shaft • Erectile tissue fills with blood • Glans penis – enlarged tip • Prepuce – foreskin

  9. Sperm • Production of sperm begins at puberty and continues throughout life in the testes During ejaculation, 2 to 5 ml of semen are released in which there are between 50-150 million sperm per ml. Infertility results when there are less than 20 million per ml.

  10. Female Reproductive System • Mammaries • Ovaries • Duct System • Fallopian tubes • Uterus • Vagina • External genitalia

  11. Female Mammary Glands Figure 16.13a

  12. Female Mammary Glands Figure 16.13b

  13. Mammograms Figure 16.14

  14. Female Internal Genitalia • A: • Ovaries • B: • Fallopian tubes – receive oocyte and provide place for fertilization • C: • Uterus – receives, retain, and nourishes egg • D: • Cervix – Bottom of uterus • E: • Vagina – thin walled tube • Birth canal – passageway for delivery of babyand menstrual flow • Receives penis during copulation

  15. Female External Genitalia • Labia – skin folds • Clitoris – contains erectile tissue • Female correspondent to penis • Greater vestibular gland (i.e. Bartholin’s Gland) – secretes lubricant

  16. Ovaries • Where eggs are produced through meiosis • Each ovary takes turns releasing one egg per month (twins = two eggs released) • Secrete progesterone and estrogen • Estrogen – secondary sex characteristics in females • Progesterone – regulates menstruation

  17. Ovaries • 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

  18. Oocyte Developing

  19. Oogenesis • Total supply of eggs are present at birth • Ability to release eggs from puberty  menopause • FSH causes some primary follicles to mature into oocytes every month • LH causes development of secondary follicle • If sperm penetrates oocyte then ovum is produced

  20. Fertilization • Sperm must travel to the egg and penetrate to combine the DNA from both parents -- this creates the first cell after fertilization: the Zygote 23 chromosomes from each parent; zygote has a total of 46 chromosomes

  21. Inner cellmass Blastocystcavity Trophoblast (a) Zygote(fertilizedegg) (b) Earlycleavage4-cell stage (c) Morula (d) Earlyblastocyst (e) Late blastocyst(implanting) (b) (c) (a) Fertilization Ovary (d) Uterine tube (e) Secondaryoocyte Uterus Ovulation Endometrium Fertilization normally occurs in the Fallopian Tubes The fertilized egg (zygote) implants in the uterus

  22. Ova • An 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.

  23. Female 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.

  24. Fluctuation of Gonadotropin Levels Figure 16.12a

  25. Fluctuation of Ovarian Hormone Levels Figure 16.12b

  26. Ovarian Cycle Figure 16.12c

  27. Uterine (Menstrual) Cycle Figure 16.12d

  28. How does a woman know she is pregnant? • Missed period • Changes in body, tenderness in breasts, nausea…etc • Pregnancy test – tests urine for hormone levels (hCG – human chorionic gonadotropin) which is produced by the blastocyst 6-12 days after fertilization

  29. Clearblue Pregnancy Test

  30. Embryo of Approximately 18 Days Figure 16.16

  31. Fetal Development

  32. Fetal Development

  33. The 7-week Embryo Figure 16.17

  34. Photographs of a Developing Fetus Figure 16.18a

  35. Development of the Human Fetus Table 16.1 (1 of 2)

  36. Development of the Human Fetus Table 16.1 (2 of 2)

  37. Baby movesdeeper intomother’s birthcanal Initiation of Labor Figure 16.19, step 1

  38. Baby movesdeeper intomother’s birthcanal Pressoreceptorsin cervix ofuterus excited Initiation of Labor Figure 16.19, step 2

  39. Baby movesdeeper intomother’s birthcanal Afferentimpulses tohypothalamus Pressoreceptorsin cervix ofuterus excited Initiation of Labor Figure 16.19, step 3

  40. Hypothalamus sends efferentimpulses to posterior pituitary,where oxytocin is stored Baby movesdeeper intomother’s birthcanal Afferentimpulses tohypothalamus Pressoreceptorsin cervix ofuterus excited Initiation of Labor Figure 16.19, step 4

  41. Hypothalamus sends efferentimpulses to posterior pituitary,where oxytocin is stored Posterior pituitary releasesoxytocin to blood; oxytocintargets mother’s uterinemuscle Baby movesdeeper intomother’s birthcanal Afferentimpulses tohypothalamus Pressoreceptorsin cervix ofuterus excited Initiation of Labor Figure 16.19, step 5

  42. Hypothalamus sends efferentimpulses to posterior pituitary,where oxytocin is stored Posterior pituitary releasesoxytocin to blood; oxytocintargets mother’s uterinemuscle Uterus respondsby contractingmore vigorously Baby movesdeeper intomother’s birthcanal Afferentimpulses tohypothalamus Pressoreceptorsin cervix ofuterus excited Positive feedbackmechanism continuesto cycle until interruptedby birth of baby Initiation of Labor Figure 16.19, step 6

  43. Stages of Labor Figure 16.20 (1 of 3)

  44. Stages of Labor Figure 16.20 (2 of 3)

  45. Stages of Labor Figure 16.20 (3 of 3)

  46. What if you don’t want to have a baby? There are lots of options…… • Temporary methods of birth control • Condom • Birth control pills • Nuva-ring • Depo-Provera (shot) • IUD (semi-permanent) • Diaphragm

  47. More Permanent Options… Vasectomy Tubal Ligation

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