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Human Growth and Reproduction Female System Terms • • • • • Vagina/birth canal Cervix Ovary Egg (ovum/ova) Fallopian tubes (oviduct) • Uterus • follicle • Menstration - release of tissue & blood through the vagina; usually occurs each month two weeks after ovulation and lasts 3 to 7 days • Hypothalamus - small portion of the brain that controls hormone release • Pituitary - "The Master Gland“; located in brain and responsible for the functioning of all other glands including thyroid, adrenals, and sex glands • Follicle Stimulating Hormone (FSH) – a hormone secreted in the pituitary that Stimulates growth & development of the ovarian follicle in females • FSH in males stimulates the production of sperm • Follicle - small sac near the surface of the ovary that contains the developing egg cell • Luteinizing Hormone (LH) - hormone produced in the pituitary gland that stimulates the development of the corpus luteum • Estrogen – female hormone that regulates development of secondary sex characteristics • Progesterone – secreted by corpus luteum; regulates the build up of endometrial tissue in the uterus • Testosterone – male hormone that regulates the development of secondary sex characteristics • Ovulation - release of mature egg cell from its follicle in the ovary • corpus luteum - yellow mass that forms in the cavity of a ruptured follicle that releases progesterone • Fertilization - union of the egg and the sperm which results in conception (formation of a zygote) • cell division – (Cleavage/Mitosis) - shortly after fertilization the egg, now called a zygote, starts to divide into 2 cells, then 4, 8, etc. • Implantation - the zygote attaches to the uterine lining and starts to draw nutrition from the blood supply (occurs between 6th & 11th days after fertilization) • Endometrium – lining of the uterus; where zygote implants • Oviduct – passageways where egg is released form ovaries; site of fertilization; also called “fallopian tubes” • Cervix – opening at lower end of uterus • Vagina – muscular organ that receives the penis and sperm Male System terms: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Penis Testicles Scrotum Epididymis Urethra Vas Deferens Prostate Gland Seminal Vesicles Cowper’s (Bulburethral) Glands Seminiferous Tubules • Penis – delivers sperm to female reproductive tract • Testicle – produces sperm & testosterone • Epididymus – sperm is stored in this tightly coiled tube • Scrotum – sac containing the testes; extension of abdomen; functions to keep the testes at a temperature slightly lower than that of the rest of the body. (for human beings, the temperature should be 1 or 2 degrees lower) • Vas Deferens – thin muscular tube that transports sperm from epididymus to the urethra • Seminal Vesicle - a pair of simple glands inferior to the urinary bladder; secretes alkaline fluid that adds to semen & neutralizes acidity of vagina • Bulbourethral (Cowpers) glands – produce a clear secretion known as pre-ejaculate which helps to lubricate the urethra so sperm can easily pass through; also neutralizes traces of acidic urine in urethra • Prostate Gland – walnut-sized gland encircling urethra that stores & produces seminal fluid • Urethra – tubes that connects urinary bladder to outside of body; travels through penis and carries semen as well as urine • Seminiferous tubules – located in testicles; location of meiosis (creation of sperm) A new study conducted by Chicago researchers shows that internal mucosal layers of foreskin are more susceptible to HIV infection than cervical tissue or the external layers of foreskin, which explains why uncircumcised men seem to be at much higher risk for HIV acquisition than men who are circumcised…this is not proven beyond a reasonable doubt…more testing is needed! A fertile man makes around 1000 new sperm per second, in the testes. Each sperm carries half the chromosomes (n or haploid) packed into its head. The rest of the cell is a long tail, which propels the sperm towards the egg at about three millimeters per minute. The neck is crammed with mitochondria, which help make the energy needed for the journey. Once they're released, sperm usually survive for 48 hours. A human egg (oocyte) is about 100 micrometers in diameter, which is large for a cell. A fertile woman usually releases one egg a month, from one of her two ovaries. Unless the egg is fertilized within the next 24 hours, it dies. At its center, the egg contains half the chromosomes (n or haploid) number for its species. The rest of the cell is a rich food store for the fertilized egg during the first few days of its life. A baby girl is born with around .5-1.5 million eggs already formed in her undeveloped ovaries. However, only about 500 are released in her lifetime, between puberty (15) and menopause (55). Ovulation • An egg (orange), almost ready to be released by a woman's ovary. • During a healthy cycle, a woman will release one or perhaps two eggs which should slowly travel down, hopefully meeting sperm on the way so it can be fertilized. Fertilization Fertilization Occurs in Fallopian Tubes (200 million sperm to one egg) When 1 sperm penetrates the zona pellucida (clear zone around egg), cortical granules are released that prevent any other sperm from penetrating the egg After fertilization, the egg and sperm and nuclei fuse, and a new diploid human zygote results (2n) - the first cell of the new animal... The egg’s journey from ovulation to fertilization to implantation Chromosomes in fertilization: After Fertilization… In the first days & weeks after conception, mitosis begins, converting the zygote to a multicellular organism 24 hour embryo (zygote) Cleavage (Mitotic Divisions) Cleavage 2-day old embryo Morula – Day 4 16-32 cell stage The solid Morula develops into a hollow Blastula: Gastrulation: major cell reorganization into 2 or 3 tissue layers Gastrulation 1. Ectoderm – skin, nervous system 2. Endoderm – lining of gut & internal organs 3. Mesoderm – muscles, bones,heart Placenta • For 9 months, it feed & nourishes the fetus with the blood supply and nutrients necessary for survival • Also disposes of the toxic waste • Develops from the sperm & egg cells that formed the fetus • Placental Barrier does NOT allow the blood from the placenta to mix with the mother’s blood…WHY? • The mother’s blood DOES NOT mix with placental blood in order to avoid the possible transfusion of different blood types form mother to baby Embryo at Day 5 Days 10 to 14 -Fluid filled amniotic cavity starts to form -Yolk sac starts to form (will make blood cells, germ cells) -Embryo starts to form from embryonic disc - Chorion (placenta) starts to form • At the end of this stage, a woman will have just missed her period! Days 10 to 14: Days 15 to 21 Neural Groove (future spinal cord and brain) begins to form Somites (bands of tissue that will become muscles and bones) begin to form Pharangeal arches (future face, neck, mouth, nose) begin to form 18-25 DAYS: • The baby is only 1/100 of an inch long • his tiny heart is already beating • By the 20th day, the foundation for the nervous system is laid down. • WEEK FOUR: By now, blood circulation is wellestablished. The larynx and inner ear are beginning to form, as are the legs and arms. The liver, pancreas, lungs, and stomach are also forming. By this point, the baby is 4-6 millimeters long from head to rump. • WEEK FIVE: The baby is now about 7-9 mm from head to rump. In the process of developing, the baby will go through three sets of kidneys. This week, the last set of kidneys appears. Day 21 on… • Development of all organ systems • Day 22: Cardiac cells (early heart) begins to beat • Day 24 embryo shown at right 4 Weeks Week 4 • After implantation, the cells of the embryo started to specialize to form the outline of the body. • the embryo measures approximately 5 mm; the head is distinct • the heart beats, and the arms and budding fingers are visible. • the placenta continues to develop, bringing the fetus all the necessary nutrients from the mother's blood. Week 4 Week 4 Week 5 Week 6 • Heart will begin to beat • Blood will start to circulate throughout baby’s body • Umbilical cord will start to form • Head, eyes, intestines, & liver all start to form Fetus at 6 weeks • 42 DAYS: The skeleton is complete and reflexes are present. Brain waves (the presence or absence of which are used as a legal means to declare a born person living or dead) can be detected. • WEEK SIX: Now the baby is about 8-11 mm. Although the mother won't be able to feel the baby's kick for many weeks to come, he is now moving in his amniotic sac. The baby has all the internal organs of an adult. The process of ossification (the hardening of the bones) begins. Week 6 Week 8 Fetus at 7 weeks Fetus at 8 weeks Week 10 • • • • End of embryonic stage of development Now known as a fetus External genitalia begin to form Facial features & limbs become more apparent • Vital organs will be formed and begin to work Fetus at 11 weeks Week 12 Fetus at 12 weeks Fetus at 12 weeks Week 14 • Reproductive organs are developing • Growing hair as well as forming eyelids, fingernails, & toenails • Head growth occurs rapidly • Bone formation forms rapidly • Digestive organs begin to function Fetus at 14 weeks Fetus at 14 weeks Fetus at 16 weeks Fetus at 16 weeks A fetus at 16 to 20 weeks begins to hear and may even be able to hear its mother’s voice! Its tiny heart pumps about 25 quarts of blood each day! Week 18 • Finger and toe pads have formed • Bones in inner ear have developed enough that fetus may start responding to loud outside sounds • Bones are distinct in X-rays • Heartbeat detected by physician • Sex organs are fully formed Fetus at 20 weeks Week 22 • Senses are well developed • Sweat glands begin to develop • Brain begins to quicken its development • Fine, downy fuzz covers the entire body • Ears & nose begin to develop cartilage Fetus at 24 weeks Fetus at 26 weeks Week 28 • Development of the retinas will be completed • Eyes will begin to open and blink • Cerebral cortex of brain develops rapidly • If born now, baby would have a 50% chance of survival with proper medical care Week 32 • Subcutaneous fat is deposited for later use • Fingernails reach beyond the fingertips • Skin becomes less transparent as fat deposits develop under skin and other areas • May respond to loud noises • Organs are almost fully mature except for the lungs Fetus at 32 weeks Fetus at 32 weeks Fetus at 36 weeks Week 36 • Hair covering the entire body is shed • Organ systems function actively • Vernix (protective substance that blankets the baby) is present over the entire body • Fetus settles into position for birt Labor & Delivery Process • In early labor, mom will feel the first contractions • Her cervix will gradually dilate • Contractions will be more frequent and painful • This stage can last for hours Active Labor • Contractions are more frequent & painful • Cervix begins to dilate, stretching from about 3 cm to the full 10 cm that is needed for delivery to begin • When mother is dilated sufficiently, she can receive medication for her pain if she chooses Transition Stage • Cervix reaches its full dilation • Contractions become stronger and more frequent, possibly coming every three minutes and last up to a minute each • Baby is descending into the birth canal • As baby moves down, mother may feel pressure and an urge to push • This stage may last anywhere from a few minutes to a few hours Apgar Score • Assesses health of newborn immediately after childbirth • (Assessment is made one and five minutes after birth of baby) • Determined by evaluating the newborn baby on 5 simple criteria on a scale from 0 to 2 • The Apgar score is a number calculated by scoring the heart rate, respiratory effort, muscle tone, skin color, & reflex irritability (response to a catheter in the nostril). Each of these objective signs can receive 0, 1, or 2 points. • A perfect Apgar score of 10 means an infant is in the best possible condition Activity (muscle tone) 0 — Limp; no movement 1 — Some flexion of arms and legs 2 — Active motion Pulse (heart rate) 0 — No heart rate 1 — Fewer than 100 beats per minute 2 — At least 100 beats per minute Grimace (reflex response) 0 — No response to airways being suctioned 1 — Grimace during suctioning 2 — Grimace and pull away, cough, or sneeze during suctioning Appearance (color) 0 — The baby's whole body is completely bluish-gray or pale 1 — Good color in body with bluish hands or feet 2 — Good color all over Respiration (breathing) 0 — Not breathing 1 — Weak cry; may sound like whimpering, slow or irregular breathing 2 — Good, strong cry; normal rate and effort of breathing Remember… The process of growth & development all need to occur at a precise time and place – that is why poor maternal nutrition, fever, drugs, alcohol, (particularly in the 1st trimester) all have potentially serious effects of the developing baby. What NOT to do during pregnancy! http://www.hip-chick-pregnancyguide.com/childbirth-video.html Miscarriages • About 15% of pregnancies end in miscarriage • Most within the first trimester • Most miscarriages occur due to chromosome abnormalities, a problem with either the egg or the sperm • Women over 35 are at greater risk for these abnormalities and/or miscarriages than younger women • Other causes of miscarriages include Infections, hormonal problems, illnesses, or diseases • Drinking alcohol, smoking, and taking certain drugs also increase the risk Ectopic pregnancy Infertility • A condition of the reproductive system that impairs the conception of children • Affects approx 6.1 million individuals throughout the United States • Diagnosis is usually given to couples who have been trying to conceive for one year without success Conception & Pregnancy depend on: • Production of healthy sperm by the man • Healthy eggs produced by the woman • Unblocked fallopian tubes that allow the sperm to meet the egg • The sperm’s ability to fertilize the egg when they meet • The ability of the fertilized egg (embryo) to become implanted in the woman’s uterus • Sufficient embryo quality In-vitro Fertilization • In IVF, doctors want to "harvest" as many eggs as possible from a woman to improve the chances of having one or more embryos to put back. • To do this, many patients are given hormones to stimulate the ovaries to produce more eggs and have them ready for "collection" on a set day. • This means daily injections of hormones - which can have side-effects. • A total of 10,000-50,000 spermatozoa are added to medium containing the oocyte. motile culture • After insemination, the oocyte is left for 12-13 hours and then inspected in a petri dish containing culture medium. • Any abnormal oocyte is noted and such embryos are not used for transfer. • The first cleavage takes place 24-30 hours after insemination • each subsequent division should occur within 10- 12 hours thereafter • If cleavage does not occur within 24 hours, this suggests abnormal oocyte, which should not be used for transfer • There is a “window of implantation” that lasts 7 days • Before & after this “window”, plantation will not occur • IVF failure is mostly due to embryo quality and NOT uterine issues • Human blastocysts should hatch from the shell and begin to implant 1-2 days after day 5 IVF blastocyst transfer • In a natural situation (not IVF), the blastocyst should hatch and implant at the same time - about 6 to 10 days after ovulation Surrogate Mothers… • Surrogacy is a method of reproduction whereby a woman agrees to become pregnant and deliver a child for a contracted party • She may be a relative of the child or she may, as a gestational carrier, carry the pregnancy to delivery after having been implanted with an embryo that is not hers. The legality of it …. • New York law holds surrogacy agreements void and unenforceable. • However, at least one court has recognized the rights of intended parents in an assisted reproduction situation absent a contract. • In one 1994 divorce proceeding, a husband sought sole custody of the two children of the marriage on the basis that his wife was their gestational, but not genetic, mother. • The wife had undergone an in vitro fertilization procedure in which she was impregnated with an anonymous donor egg fertilized with her husband’s sperm. • The Court found the gestational mother to be the legal mother of the children, based on the intent of the parties regarding parentage. • In one case in 1990, decided before the statutory ban on surrogacy agreements was passed, a married couple had entered into an extensive contract with a surrogate, including a $10,000 “surrogate fee.” • The Court found the surrogate’s commitment to relinquish the child she carried could not be truly voluntary because of the financial inducement. • The Court went on to find that its conclusion might be altered by a sworn statement by the surrogate that the child’s best interests lie with the contracting couple,