Human Reproductive System

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Human Reproductive System

• Living Environemnt

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• 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.

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• 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
  Pelvis
• 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
  hormones.

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• 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
  vagina.
• 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.

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• 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.

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• 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.

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Week 3 Week 4 Week 5



Week 6 Week 7 Week 8

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• 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.

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• 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.

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• 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
  occur.
• When the cervix is completely expanded the
  amniotic membrane bursts lubricating the birth
  canal.
• 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.

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

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

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