SHEL011 Test 2

• Growth


  Increase in size
• Development


  Continuous process by which an individual changes from one life phase to another
• Life phases


  • Prenatal period
  • Postnatal period
• Prenatal period


  Begins with fertilization of an egg cell and ends at birth
• Postnatal period


  Begins at birth and ends with death
• Fertilization


  Union of a secondary oocyte and a sperm cell
• Pregnancy


  Presence of a developing offspring in the uterus
• Pregnancy trimesters


  • First trimester
  • Second trimester
  • Third trimester
• Transport of sex cells


  1. Sperm cells move upward through uterus and uterine tube

  2. Prostaglandins in semen stimulate sperm tails

  3. Muscular contractions in uterus and uterine tube aid sperm journey

  4. Sperm reaches and fertilizes secondary oocyte
• Capacitation


  Physiological changes of spermatozoa in female genital tract before they can fertilize the egg
• Conception/fertilization


  1. Sperm and egg unite

  2. Forms a zygote

  3. Genetic material of egg and sperm combine

  4. Occurs in fallopian tube

  5. Implantation in uterine wall after a few days
• Embryo


  Cluster of cells between 3-8 weeks of pregnancy
• Fetus


  Developing cells after the 8th week of pregnancy
• Cleavage


  1. Zygote undergoes mitosis, forming smaller and smaller cells

  2. Cells are called blastomeres

  3. Forms a morula and then a blastocyst

  4. Blastocyst implants in uterine wall
• Embryonic stage


  1. Major organ systems develop

  2. Placenta and umbilical cord develop

  3. Face and limbs take shape
• Fetal stage


  1. Head is disproportionately large at first

  2. Body lengthening accelerates, head growth slows

  3. External reproductive organs distinguish as male or female by 12th week
• First trimester development


  • Week 5: Circulatory system, brain and spinal cord begin to form, heart forms and beats
  • Week 6: Nose, mouth and ears start to form
  • Week 7-8: Embryo doubles in size, hands and feet start to grow
  • Week 9-13: Embryo becomes fetus, facial features more recognizable, diaphragm muscles start to grow, reproductive, circulatory and urinary systems advance, fetus is about 5cm in size
• Fetal development: First Trimester (1-3 months/1-13 weeks)


  1. Week 5: Circulatory system and brain & spinal cord begin to form. Tiny heart forms and begins to beat.

  2. Week 6: Nose, mouth and ears start to shape

  3. Week 7 & 8: Embryo has doubled in size. Little hands and feet start to grow

  4. Week 9-13: Embryo is called a fetus, baby is almost fully formed and completed the most critical portions. Facial features are more recognizable. Fetus head is rotated and bent towards the chest and it can occasionally touch its face, the diaphragm muscles start to grow. Reproductive, circulatory and urinary systems are all at an advanced stage of development. Fetus will urinate in the amniotic sac, a sign of proper function of the fetus's body. If a girl, her ovaries contain millions of eggs. If a boy, his testicles will start producing testosterone, the male sex hormone. Fetus is about 5cm in size and 14g in weight.
• Fetal development: Second Trimester (4-6 months/14-27 weeks)

  1. 15-20 weeks: Eyes can blink, body begins to grow, head growth rate slows, limbs reaching normal proportions, eyebrows and eyelashes develop. Fetus can grasp and kick. Heartbeat can be heard. Fetus recognized voices and it grows hair and nails.

  2. 21-28 weeks: Fetus can hear conversations, has regular cycle of waking & sleeping, weight increases rapidly. Quickening: when your baby is moving around. May survive outside the womb after 24 weeks with special medical care.
• Vernix caseosa


  White waxy, cheese-like substance that forms over the entire surface of the fetal skin. Protects the skin from constant exposure to amniotic fluid and serves as a skin cleanser and antibacterial substance.
• Lanugo


  White, downy hair that covers the entire body of the fetus. Provides warmth, since the fetus has no layer of fat beneath the skin yet.
• Fetal development: Third Trimester (28-40 weeks/7-9 months)


  The fetus gains most of its weight during this trimester and is able to grasp objects as well as open and close its eyes. 29 to 40 weeks: Fetus able to use all 5 senses and water able to pass through bladder. Brain scans have shown that some fetuses dream. Fat starts to form under baby's skin to help fill out wrinkles and gaining over half the weight.
• Approximately 266 days after conception, the baby weighs 2.5kg-4.25kg at birth.
• Colostrum


  Yellowish fluid that starts leaking from the mother's breasts. It contains immune cells, antibodies, and proteins to get the breasts ready for making milk.
• Full "term" delivery any time after 39/40 weeks.
• Components of the womb

  • Umbilical cord
  • Placenta
  • Amniotic sac filled with amniotic fluid
• Besides oxygen and nutrients, the umbilical cord can also deliver nicotine, alcohol, drug compounds, and other things ingested, inhaled, or absorbed through the skin of the mother.
• Chorionic Villi


  Part of the placenta that absorb food and oxygen from the mother's blood
• Childbirth is hormonally induced and occurs in three stages

  1. Labor is controlled by a positive feedback mechanism

  2. Estrogen released from the ovaries increases the sensitivity of the uterus to oxytocin

  3. Oxytocin is a powerful stimulant for the smooth muscles of the uterus

  4. Oxytocin also stimulates the placenta to make prostoglandins that stimulate the uterine muscles to contract even more

  5. Uterine contractions stimulate the release of more and more oxytocin and prostoglandins
• Stages of Labor


  1. Dilation/contraction stage: From the onset of labor until the cervix is fully dilated (10 cm). The uterine smooth muscle begins to contract, moving the fetus down the uterus and causing the cervix to dilate.

  2. Expulsion/delivery stage: From fully dilated to when the baby is actually delivered. Natural - vaginal delivery, which is most common, is when the baby is delivered through the vagina. Cesarean - baby surgically removed via incision into abdomen. Episiotomy: An incision made in perineum during childbirth, only recommended in certain cases.

  3. Placental/afterbirth stage: The last stage of labor. Also known as afterbirth. Placenta is still attached to the umbilical cord. Contractions continue until the placenta (now called afterbirth) is pushed out due to final uterine contractions.
• Nutrition is extremely important during pregnancy. Eating a well-balanced diet can prevent birth defects in the fetus, low-birth weight/mortality of the infant, a difficult labor/delivery, and mortality of the mother during childbirth. If the fetus does not receive the nutrients it needs through the mother's diet, it will take them from the mother's own system.
• Common health problems developing during pregnancy

  • Preeclampsia and Eclampsia (high blood pressure)
  • Gestational Diabetes
  • Infections (toxemia)
  • Clotting Disorders
• Common disorders of pregnancy

  • Placental Problems
  • Preterm Labor
  • Preterm Premature Rupture of the Membranes
• Fetal complications


  • Congenital Abnormalities
  • Growth Abnormalities
• Remember exercise and the emotional health of the mother as well!
• Pregnancy complications


  • Placenta previa is the development of the placenta over the opening of the cervix
  • Preeclampsia is a pregnancy-induced hypertension (high blood pressure)
  • Spontaneous abortion or miscarriage is the loss of a fetus during the first 20 weeks, often due to abnormalities, trauma, or lifestyle choices.
• Postnatal period


  1. Neonatal period

  2. Childhood

  3. Adolescence

  4. Adulthood

  5. Senescence (including dying)
• Reproductive technology


  • Hormone therapy can increase sperm or egg production
  • Surgery can correct blocked oviducts
  • In vitro fertilization (IVF)
  • Surrogate motherhood