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Human Reproduction.

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Presentation on theme: "Human Reproduction."— Presentation transcript:

1 Human Reproduction

2 Human Reproduction

3 Human Reproduction Male Reproductive Anatomy
Spermatogenesis and Male Hormones Male Reproductive Technologies and Birth Control Female Reproductive Anatomy Oogenesis and Female Hormones Uterine and Ovarian Cycles Development of the Fetus Parturition and Lactation Teratogens and Birth Defects Reproductive Technologies

4 Human Reproduction

5 Reproduction ensures the survival of a species
Sexual reproduction produces offspring with new and unique characteristics that may increase their chance of survival.

6 Reproduction 2 types of gametes (sex cells)
Males: 1 billion sperm each day from the ages 13-90 Females: born with 400, 000 eggs, 400 mature from ages 12 to 50

7 Reproduction The average gestational period for a human is 266 days.

8 Male Reproductive System
The male reproductive structures are responsible for: producing sperm storing sperm delivering sperm to the female

9 Male Reproductive System

10 Male Reproductive System
Scrotum holds the testes away from the body to keep them cool. Sperm production only occurs at temperatures about 3 degrees below body temperature.

11 Male Reproductive System
Testis descend about 2 months before birth spermatogenesis seminiferous tubule that produce sperm

12 Male Reproductive System
Epididymis – holds sperm for about 2-4 days while they mature

13 Male Reproductive System
Vas Deferens conducts sperm during ejaculation vasectomy: the vas deferens cut and tied off, to prevent conduction of sperm.

14 Male Reproductive System
Ejaculatory Duct –propels semen and sperm through the urethra. Urethra –conduction of urine and semen out of the penis. a sphincter muscle closes off the bladder, preventing urine from exiting the urethra.

15 Male Reproductive System
Penis male organ for copulation. Beneath the skin, lies the urethra surrounded by spongy protective tissue that expands to form the glans penis. Prepuce (foreskin) – is a loose sheath of skin covering the glans penis of uncircumcised males. The foreskin produces an oily secretion known as smegma.

16 Seminal Fluid Is produced by three different glands: Seminal Vesicles
fluid high in fructose that provides energy sperm need to swim Prostaglandins which cause contractions of muscles in the female reproductive tract to help move sperm in

17 Seminal Fluid Prostate Gland Cowper’s Gland
milky white alkaline fluid that neutralizes the acidity of the vagina Cowper’s Gland buffered fluid that cleanses and neutralizes the acidity in the urethra

18 Spermatogenesis Spermatozoa – are the smallest cells in the body. They have very little cytoplasm in the head, and a large tail (flagellum).

19 Spermatogenesis Spermatogonia – undifferentiated germ cells that have 46 chromosomes Primary Spermatocytes – larger cells that undergo meiosis I

20 Secondary spermatocytes – cells that undergo meiosis II
Spermatids – cells with 23 chromosomes, that are ready to mature in the epididymis Spermatozoa – mature sperm cells

21 Sertoli Cells- nourish sperm cells


23 Terminology Erection parasympathetic nerve impulses dilate the arteries of the penis, allowing blood to flow rapidly into the highly vascular penile tissue veins are compressed preventing blood from leaving the penis.

24 Terminology Ejaculation – occurs when sexual stimulation forces semen to the urethra, where rhythmical muscle contractions cause the semen to be expelled from the penis. Infertility – the inability to produce viable sperm. Impotency – the inability to achieve a sustained erection.

25 Regulation of the Male Reproductive Hormones

26 Male Reproductive Hormones
GnRH : gonadotropic releasing hormone released from hypothalamus stimulates the anterior pituitary to release LH and FSH LH : luteinizing hormone stimulates the interstitial cells (cells in between seminiferous tubules) of the testes to produce testosterone

27 Male Reproductive Hormones
Testosterone – responsible for male secondary sex characteristics, required for sperm production FSH: follicle stimulating hormone stimulates production of sperm in the seminiferous tubules

28 Male Reproductive Hormones
Inhibin produced by Sertoli cells when sperm count is high Sends feedback to inhibit FSH and GnRH


30 Female Reproductive Structures
The female reproductive structures are responsible for reception of sperm producing an egg nourishing and protecting the fetus delivering the baby

31 Female Reproductive Structures

32 Female External Structures (Vulva)
Labia majora – large, fatty, hair covered folds that protect the genitals Labia minora – smaller folds of skin inside the labia that are kept moist by secretions Clitoris – small shaft of erectile tissue

33 Female Internal Structures
Vagina intercourse : accepts the penis birth canal during labor pH is generally acidic

34 Female Internal Structures
Cervix Thick muscular tissue plugs closed with mucous during pregnancy prevents material from getting into the uterus, and holds the baby in

35 Female Internal Structures
Uterus (womb) pear shaped muscular organ (5 cm wide) houses the developing fetus during pregnancy (30 cm wide) strong contractions help push the baby out during birth

36 Female Internal Structures
Ovaries produce the ovum from follicles found in the outer cortex

37 Female Internal Structures
Oviducts /Fallopian tubes conduction of the ovum (egg) from the ovaries to the uterus where fertilization usually takes place If egg implants here = ectopic pregnancy frequency

38 Female Internal Structures
Fimbriae small fingerlike projections at the ends of the oviducts that sweep to draw the egg into the fallopian tube

39 Female Internal Structures

40 Ovarian Structures Follicle cells that support and protect the ovum
secrete estrogen to mature the ovum become a corpus luteum following ovulation. Ovum – egg cell, viable for about 24 hours after release.

41 Ovarian Structures Corpus Luteum
cells remaining after a follicle has ruptured during ovulation secretes progesterone and some estrogen for about 3 months if fertilization and pregnancy occurs deteriorates after about 14 days if fertilization does not occur.

42 Oogenesis

43 Regulation of the Female Reproductive Hormones
GnRH – stimulates the anterior pituitary to produce FSH and LH FSH – stimulates development of the follicle and the production of estrogen within the ovary

44 Regulation of the Female Reproductive Hormones
LH – causes ovulation, development of the corpus luteum which secretes progesterone

45 Reproductive Hormones
Estrogen secreted by the follicles in the ovaries causes maturation of the egg stimulates growth of the endometrium (uterus lining) Female secondary sex characteristics Inhibits FSH

46 Reproductive Hormones
Progesterone secreted by the corpus luteum continues preparation of endometrium inhibits both FSH and LH to prevent ovulation prevents uterine contractions firms the cervix

47 P 525 Fig 6

48 The Uterine and Ovarian Cycles

49 Day 1-5: Menstruation/Flow Phase
Estrogen and progesterone levels are low endometrium is sloughed off and shed Day 1-13: Follicular Phase FSH secreted from ant. pit. promotes development of the follicle follicle releases estrogen, which promotes growth of the endometrium.

50 Day 14: Ovulation An increase in LH causes the ovum to be released FSH is lowered Day 15 – 28: Luteal Phase LH promotes formation of the corpus luteum corpus luteum produces progesterone, inhibits GnRH, LH and FSH, preventing subsequent ovulation.

51 Many birth control pills are high in progesterone which prevents ovulation


53 No Fertilization  corpus luteum degenerates, estrogen and progesterone levels drop, and menstruation occurs.

54 The Uterine Cycle Menstrualcycle

55 Fertilization Fertilization
-union of sperm and secondary oocyte in the fallopian tube Only one spermatozoa will fertilize an egg Now called a zygote fertilization

56 Early Embryonic Development
Zygote –fertilized egg, divides by cleavage, mitosis with no increase in size 36 hours: 1st division (2 cells) 60hours: 4 cells 72h: 8 cells Morula – solid ball of cells the same size as the fertilized egg (day4-5)

57 Early Embryonic Development
Blastocyst hollow ball of cells filled with fluid, outer layer forms the chorion, inner layer forms the embryo Implants day 7-10

58 Early Embryonic Development

59 Implantation embryo embeds itself in the endometrium.
produces HCG (human chorionic gonadotropic hormone): maintains the corpus luteum for about 2-3 months. Reminder: corpus luteum produces progesterone and estrogen to maintain the endometrium and prevent ovulation)

60 hCG Pregnancy Test ELISA
HCG detected in blood or urine with a pregnancy test hCG Pregnancy Test ELISA

61 Early Embryonic Development
Gastrula the blastocyst pushes in (invaginates) and forms the 3 primary germ layers the hollow space forms a primitive gut 2nd week

62 Gastrulation

63 Germ Layers Ectoderm – nervous system and epidermis of the skin
(hair, nails,retina, lens, inner ear, lining of the nose, mouth, anus and tooth enamel) Neurula- notochord/neural tube forms from the ectoderm layer (forms in 3rd to 4th week)

64 Germ Layers

65 Germ Layers Mesoderm – skeleton, muscles, reproductive organs
(connective tissue,cartilage, blood, blood vessels, kidneys) Endoderm –lining of the digestive and respiratory system, endocrine glands (trachea, bronchi, lungs, gallbladder, urethra, liver, pancreas, thyroid,bladder)

66 Gastrulation Embryonic development

67 Embryo at 4 weeks

68 Extra Embryonic Membranes
Amnion – inner membrane filled with fluid to provide protection, maintain temperature, swallowing Chorion-outer membrane, contributes to placenta Extraembryonic coelom – fluid filled space between amnion and chorion

69 Extra Embryonic Membranes
Allantois – collects nitrogenous wastes and forms the umbilical blood vessels Yolk Sac – surrounds embryo, first site of blood cell formation, becomes part of the primitive gut

70 Extra Embryonic Membranes
Placenta forms around the fetus exchange of gases, delivery of nutrients and removal of wastes for the fetus

71 Extra Embryonic Membranes
no blood shared between the mother and the fetus Produces progesterone and estrogen at about 4 months


73 How Old Are You? Gestational age
-calculated from the first day of the mother’s last menstrual period. –length of pregnancy is 40 weeks

74 How Old Are You? Fertilization age –actual age of the fetus
- estimated to be about two weeks after the date of the last menstrual period. To calculate due date: LMP –3 months + 7 days calculator

75 Weeks 1 -9

76 Trimesters 1rst : until end of third month 2nd: 4-6months
3rd : 7-9 months

77 Developmental Milestones
1 week – fertilization, cleavage, blastocyst 2 weeks – implantation, chorion secretes HCG, 3 germ layers form

78 Developmental Milestones
3 weeks – nervous system is evident, heart begins to form (2 tubes), heart beats around day 22 4-5 weeks – limb buds appear, eyes, ears and nose develop, umbilical cord is attached to placenta

79 Developmental Milestones
6-8 weeks – fetus is recognizable as a human, all organ system are developed, reflexes begin (size = 1.5”, 0.5 g) 8th week = fetus

80 9-16 weeks – heartbeat is audible with a stethoscope, bone replaces cartilage, eyelashes formed, fetus can suck and swallow (size = 6”, 0.5 lb)

81 Developmental Milestones
17-28 weeks – movement is felt by mother, eyelids open (size = 12”, 3lb) Week 25: premature baby has 50% chance of survival

82 Developmental Milestones
32 weeks: fetus moves to head down position and lungs mature (good survival rate if born)

83 Developmental Milestones
after about 32 weeks significant weight gain 40 weeks: full term (size = 21”, 7.5 lbs) See summary chart on page 534

84 Developmental Milestones

85 Virtual Development Conception to Birth Visible Embryo


87 Teratogens Teratogens - chemical substances or infections that cause specific birth defects

88 Teratogens -Thalidomide-prescribed for morning sickness in the late 50’s and early 60’s -rubella during the first 12 weeks of pregnancy: eye problems, hearing problems and heart damage.

89 Parturition: Birth Hormones:
-relaxin: made by placenta, loosens pelvis ligaments -prostaglandins – contractions -oxytocin from Post. Pit - contractions

90 Parturition Stage 1 – dilation and effacement(thinning) of the cervix, mucous plug dislodges, uterine contractions open the cervix Stage 2 – delivery of the baby, cervix is dilated to about 10 cm, intense contractions every 1-2 min push the baby down the birth canal Stage 3 – delivery of the placenta

91 Parturition The average labor lasts about 12 hours, but can range from 1 hour to 36 hours. caesarean section may be required. involves removing the baby from an incision in the front of the abdomen.

92 Lactation prolactin stimulates the glandular tissue in the breasts to produce fluids, colostrum, and milk. Colostrum is a rich fluid containing mostly sugar and proteins. This first milk is believed to play a role in early immunity.

93 Lactation Regular suckling stimulates the pituitary gland to release oxytocin causes weak uterine contractions to return it to its pre pregnancy shape causes “let down” of milk 1.5 L of milk each day

94 Reproductive Technologies and Health
Pap Smear – a sample of cervical cells are taken and examined for abnormal growth (cancer) Ultrasound – uses sound waves to view the baby in the womb Ultrasound Scan Fetal Video Clips

95 Reproductive Technologies and Health
Amniocentesis – sampling of the cells from the amniotic fluid at about 16 weeks to check for genetic abnormalities Amniocentesis Flash Animation

96 Reproductive Technologies and Health
Chorionic Villus Sampling – sampling of cells from the chorion at about 5 weeks to check for genetic abnormalities

97 Fertility Technologies
IVF – in vitro (in glass) fertilization – fertilizing the egg in a petri dish, and implanting the embryo 2-4 days later Life Changine Science - Program 3: IVF AID – artificial insemination by donor, sperm is artificially placed in the vagina.

98 Fertility Technologies
Egg Screening – testing and selecting eggs to be fertilized, fertility drugs produce eggs that are collected using a needle biopsy TSE – testicular sperm extraction removal of sperm via biopsy (not ejaculation) ICSI – intracytoplasmic sperm injection sperm head is injected directly into the egg

99 Fertility Technologies
GIFT – gamete intra-fallopian transfer sperm and egg are transferred to the fallopian tube for fertilization AH – assisted hatching a chemical solution is dripped over the egg to allow the sperm to penetrate more easily

100 Fertility Technologies
Embryo Transfer – implantation of an embryo (at blastocyst stage) into the womb or fallopian tube, may be frozen or unfrozen Fertility Drugs – induce ovulation, usually many ova are produced at one time, often results in multiples

101 Fertility Technologies

102 Human Reproduction

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