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Human Reproductive System


Human Reproductive System Living Environemnt Puberty when a person becomes sexually mature and is capable of reproduction. Male Reproductive System: Gonads ... – PowerPoint PPT presentation

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Title: Human Reproductive System

Human Reproductive System
  • Living Environemnt

  • Puberty when a person becomes sexually mature
    and is capable of reproduction.
  • Male Reproductive System
  • Gonads Testes
  • Gametes Sperm Cells
  • Sperm Cells made in the testes
  • Testes - also act as an endocrine gland secreting
    testosterone, which is responsible for secondary
    sex characteristics. Body Hair, muscle
    development, deeper voice

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  • Each testis consists of small coiled tubes called
    the Seminiferous Tubules. Immature sperm are
    produced in the seminiferous tubules. After
    being produced sperm move to the epididymis where
    they are stored. Lave the epididymis through the
    vas deferens.

  • The two vas deferens meet at the urethra. Glands
    secrete fluids into the sperm. The mixture or
    fluids and sperm semen. The semen passes
    through the urethra by the process of
    ejaculation. Urine is blocked shortly before and
    after ejaculation.

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  • Female Reproductive System
  • Gonads Ovaries
  • Gametes Eggs
  • Ovaries make Eggs
  • Ovaries also secret female hormones including
    estrogen, which is responsible forsecondary sex
    characteristics. Breast Development, Broadened
  • 2 ovaries that contain about 200,000 tiny egg
    sacs called follicles. Each Follicle contains 1
    immature egg. These immature eggs are present at
    the time of birth.

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  • When one of the follicles ruptures the egg is
    released at the surface of the ovary ovulation.
    First occurs at puberty.
  • Oviduct or Fallopian Tube tube with funnel like
    opening. Ciliated cells draw the egg into the
    oviduct. Passes through the oviduct into the
    uterus. Uterus thick walled muscular pear
    shaped organ.
  • Once the egg is in the uterus it can be
    fertilized by a sperm cell.
  • Cervix connects uterus to the Vagina. During
    Pregnancy the child will pass through the cervix
    and leave the mother through the Vagina.

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Menstrual Cycle
  • Mature egg is developed and released from one of
    the ovaries approximately every 28 days.
  • The walls of the uterus have been building up
    preparing to accept the egg.
  • If the egg is not fertilized the wall of the
    uterus breaks down. Material from the wall and
    the unfertilized egg and eliminate from the body.
  • The cycle begins again with the maturing of
    another egg.
  • This process is called the menstrual cycle.
  • Begins during puberty age 12-15.Controled by

  • Stages of the Menstrual Cycle
  • Follicle Stage FSH (Follicle) Stimulating
    Hormone is secreted by the pituitary gland. FSH
    causes several follicles to begin to develop.
    Usually only one matures. As the follicle
    develops it secretes estrogen. Estrogen causes
    the uterine lining to become thicker.Usually
    lasts about 10 days
  • Ovulation High level of estrogen in the blood
    causes the pituitary gland to decrease the
    secretion of FSH and begin the secretion of LH
    (Luteinizing Hormone).When LH levels reach a
    certain point ovulation occurs. Follicle
    ruptures. Usually Takes place in the middle of
    the menstrual cycle.
  • Corpus Luteum Stage After ovulation LH causes
    the ruptured follicle to fill with cells forming
    a yellow body called the corpus luteum. Corpus
    Luteum begins to excrete the hormone
    progesterone, which continues the growth of the
    uterine lining. Lasts about 14 days.
  • Menstruation No fertilization occurs

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  • Menstruation No fertilization occurs
  • LH levels drop off
  • Corpus Luteum breaks down
  • Progesterone levels drop off
  • Thick lining of uterus can not be maintained so
    it breaks down
  • The extra lining, unfertilized egg, and a small
    amount of blood pass out the body through the
  • Lasts about 4 days
  • Pituitary gland begins to produce FSH again
  • New egg begins to develop and cycle starts all
    over again
  • Menstrual Cycle will stops temporarily during
    pregnancy. Around middle age (45-50) will stop
    permanently menopause.

  • Fertilization and Development
  • Sex - Hundreds of millions of sperm are
    ejaculated into the vagina. Travel through the
    cervix, across the uterus, and into the oviducts.
    If an egg is passing through the oviducts
    fertilization may occur. Zygote is formed.

  • Implantation Zygote undergoes cleavage
    developing into a blastula. At the same time it
    is moving down the oviduct toward the uterus.
    5-10 days after fertilization zygote enters the
    uterus. Outer cells of the zygote secrets
    enzymes that eat away the lining of the uterus.
    Zygote attaches to that spot.
  • Three germ layers develop. From this point on
    the developing human is called an Embryo. After
    8 weeks the developing human is called a fetus.

Week 3 Week 4 Week 5

Week 6 Week 7 Week 8

  • During pregnancy the menstrual cycle is stopped.
    A hormone is secreted that prevents the break
    down of the corpus luteum, which continues to
    secrete progesterone, which maintains the thick
    lining of the uterus.
  • In Vitro fertilization fertilization occurs
    outside the body in a lab then zygote is placed
    back in the females uterus to develop.

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  • Between fertilization and implantation embryo
    survives off of food stored in the egg. After
    implantation embryo receives food and oxygen from
    the mother through the placenta.
  • Outer layer of blastula forms chronin. Chronin
    membrane that surrounds the embryo. Chronin
    villi project into the uterine lining and form
    the placenta.

  • Placenta has fetal side (fetuss blood) and
    maternal side (mothers blood). Mothers blood
    and Fetuss blood never mix. Fetus is connected
    to the placenta by the umbilical cord. Carries
    nutrients and oxygen to the fetus, waste out of
    and away from the fetus. Placenta protects the
    fetus from harmful agents in the mothers blood.
    Some things can still pass through the placenta
    some viruses, alcohol, nicotine, most drugs.

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  • Extraembryonic Membranes same as birds and
    reptiles, different purposes. Chronin
    implantation. Amnion filled with amniotic
    fluid, which surrounds and protects the fetus.
    Allantois and yolk sac develops into the
    umbilical cord.

  • Birth
  • Gestation period length of pregnancy. In
    humans it is about nine months.
  • When the fetus is ready to be born the uterus
    begin slow rhythmic contractions labor.
  • Same time cervix begins to enlarge. It must
    expand from 1 to 2cm to 11 or 12cm for birth to
  • When the cervix is completely expanded the
    amniotic membrane bursts lubricating the birth
  • Contractions force the fetus, head first, from
    the uterus into the vagina and out of the
    mothers body.
  • Once outside the mothers body the umbilical cord
    is still attached. It is tied and cut leaving a
    scar naval or belly button.
  • Contractions continue after birth which expel the
    placenta and amnion afterbirth.

  • Fraternal Twins two eggs become fertilized,
    imbed separately and develop separately.

  • Identical twins a fertilized egg divides into
    two embryos at an early stage of development.
    Each embryo then forms separately. Pregnancy

  • Postnatal Development
  • Birth
  • Growth
  • Puberty
  • Adult
  • Aging
  • Death