Biological Beginnings: Fertilization and Gestation
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Questions and Answers

What is the term for the period of development between conception and birth?

  • Infancy
  • Prenatal stage
  • Fertilization
  • Gestation (correct)

    • What describes dizygotic twins?

  • Twins born from a single fertilization event
  • Twins formed from the union of two separate ova and sperm (correct)
  • Twins that are genetically identical
  • Identical twins resulting from a single zygote

    • What is the typical duration of gestation in humans?

  • 40 weeks (correct)
  • 35 weeks
  • 45 weeks
  • 30 weeks

    • How is gestational age usually calculated?

    <p>From the first day of the last menstrual cycle</p> Signup and view all the answers

    What is a common symptom of early pregnancy?

    <p>Mood swings</p> Signup and view all the answers

    What results in monozygotic twins?

    <p>The division of a single zygote after fertilization</p> Signup and view all the answers

    Which of the following describes conjoined twins?

    <p>Twins who share physical organs and sometimes are separable by surgery</p> Signup and view all the answers

    What is NOT an early sign of pregnancy?

    <p>Increased appetite</p> Signup and view all the answers

    What does the cephalocaudal principle dictate regarding development?

    <p>Development proceeds from the head to the lower part of the trunk.</p> Signup and view all the answers

    During which stage does implantation occur?

    <p>Germinal Stage</p> Signup and view all the answers

    Which layer differentiates into the digestive system and respiratory system?

    <p>Endoderm</p> Signup and view all the answers

    What is the primary function of the placenta during prenatal development?

    <p>Allowing the exchange of oxygen, nourishment, and wastes</p> Signup and view all the answers

    At what point does the fetal stage of development begin?

    <p>At 8 weeks</p> Signup and view all the answers

    What characterizes the embryonic stage of prenatal development?

    <p>Rapid growth and development of major body systems</p> Signup and view all the answers

    What term refers to the loss of a baby before the 20th week of gestation?

    <p>Miscarriage</p> Signup and view all the answers

    Which layer will develop into the nervous system and sensory organs?

    <p>Ectoderm</p> Signup and view all the answers

    What is a deficiency of folic acid most likely to cause?

    <p>Anencephaly</p> Signup and view all the answers

    Which supplement is mentioned as reducing the likelihood of low birth weight in babies?

    <p>Zinc</p> Signup and view all the answers

    According to recommendations, how should women in low-risk pregnancies approach exercise?

    <p>Follow their own abilities and stamina</p> Signup and view all the answers

    What serious outcome is associated with thalidomide when used during pregnancy?

    <p>Severe facial deformities</p> Signup and view all the answers

    What is the leading cause of birth defects in the United States?

    <p>Prenatal alcohol exposure</p> Signup and view all the answers

    What is the effect of maternal smoking during pregnancy?

    <p>Increased likelihood of low birth weight</p> Signup and view all the answers

    What risk is associated with consuming 4 or more cups of coffee per day during pregnancy?

    <p>Increased risk of sudden death in infancy</p> Signup and view all the answers

    Which maternal illness is known to cause deafness and heart defects in the baby if contracted early in pregnancy?

    <p>Rubella</p> Signup and view all the answers

    What is the average weight of a neonate at birth?

    <p>7 ½ pounds</p> Signup and view all the answers

    What is vernix caseosa?

    <p>A protective oily substance on newborns</p> Signup and view all the answers

    By what day do neonates generally return to their birth weight?

    <p>10th to 14th day</p> Signup and view all the answers

    What is the primary purpose of the umbilical cord during childbirth?

    <p>To attach the baby to the mother's body</p> Signup and view all the answers

    Which of the following subtests is NOT part of the Apgar Scale?

    <p>Color vision</p> Signup and view all the answers

    What is meconium?

    <p>Waste formed in the fetal intestinal tract</p> Signup and view all the answers

    What is a significant risk associated with cesarean deliveries?

    <p>Potential damage to pelvic organs</p> Signup and view all the answers

    What hormone is stimulated during vaginal delivery that is important for the mother's physical response?

    <p>Oxytocin</p> Signup and view all the answers

    What is a sign of a neonate's condition if they score 5-7 on the Apgar Scale?

    <p>Baby needs help to establish breathing</p> Signup and view all the answers

    What can be a consequence for the baby if delivered via cesarean rather than vaginally?

    <p>Increased risk of respiratory issues due to lack of hormone surge</p> Signup and view all the answers

    Which area of a neonate's head is formed by skull bones not meeting?

    <p>Fontanels</p> Signup and view all the answers

    What does VBAC stand for?

    <p>Vaginal Birth After Cesarean</p> Signup and view all the answers

    When does a newborn's heartbeat typically stabilize?

    <p>By the 10th day</p> Signup and view all the answers

    Who may be considered unsuitable for attempting a VBAC?

    <p>Women with a high body mass index</p> Signup and view all the answers

    What is a poorly timed characteristic of labor that may lead to a cesarean delivery?

    <p>Labor progresses too slowly</p> Signup and view all the answers

    How often do women who have had a cesarean delivery go on to have another cesarean?

    <p>About 92%</p> Signup and view all the answers

    Study Notes

    Biological Beginnings

    • Fertilization is the union of a sperm and ovum to produce a zygote, also known as conception.
    • A zygote is a one-celled organism.
    • Ovulation is the release of an ovum from a mature follicle in the ovary.
    • The prenatal stage spans approximately 40 weeks or 280 days, including two weeks to account for the last menstrual period and ovulation.
    • The average human gestation is from 37-41 weeks.
    • Infants born before 37 weeks are considered pre-term, while those born at or beyond 42 weeks are called post-term.
    • Gestation refers to the developmental period between conception and birth.
    • Gestational age is the age of an unborn baby, typically calculated from the first day of the expectant mother's last menstrual cycle.
    • Early signs and symptoms of pregnancy include: tender and swollen breasts or nipples, fatigue, slight bleeding or cramping, food cravings, nausea, frequent urination, frequent mild headaches, constipation, mood swings, faintness, and dizziness.

    Multiple Births

    • Dizygotic twins (fraternal twins) are conceived when two different ova are fertilized by two different sperm cells, or when a single ovum splits and is fertilized by two sperm cells; they are genetically similar to siblings.
    • Monozygotic twins (identical twins) result from the division of a single zygote after fertilization; they are genetically identical.
    • Conjoined twins are physically joined at birth, possibly sharing organs, and are sometimes surgically separable depending on the degree of fusion.

    Prenatal Development Principles

    • Cephalocaudal principle: From the Latin "head to tail," development progresses from the head to the lower part of the trunk.
    • Proximodistal principle: from the Latin "near to far," development proceeds from the center of the body outwards.

    Stages of Prenatal Development

    • Germinal Stage (first 2 weeks):
      • Characterized by rapid cell division, blastocyst formation, and implantation in the uterine wall.
      • Implantation occurs around day 6.
      • The embryonic disk, a thickened cell mass, forms and differentiates into three layers:
        • Ectoderm: upper layer that will become the outer layer of skin, nails, hair, teeth, sensory organs, and the nervous system.
        • Endoderm: inner layer that will become the digestive system, liver, pancreas, salivary glands, and respiratory system.
        • Mesoderm: middle layer that will become the inner layer of skin, muscles, skeleton, and excretory and circulatory systems.
      • The amniotic sac, a fluid-filled membrane, encases the developing embryo, cushioning it and allowing movement and growth.
      • The placenta facilitates oxygen, nourishment, and waste exchange between mother and embryo.
      • The placenta is connected to the embryo via the umbilical cord.
      • Nutrients from the mother’s bloodstream flow through the embryonic blood vessels and are transported via the umbilical cord to the embryo.
    • Embryonic Stage (weeks 2-8):
      • Marked by rapid growth and development of major body systems and organs.
    • Fetal Stage (weeks 8 to birth):
      • Characterized by increased differentiation of body parts and significant growth in body size.

    Factors Affecting Prenatal Development

    • Threats to Prenatal Development:
      • Miscarriage: loss of the baby before the 20th week of gestation.
      • Folic Acid Deficiency: lack of folic acid, derived from fresh fruits and vegetables, can lead to anencephaly and spina bifida.
      • Malnutrition: Caloric dietary supplements can benefit malnourished pregnant women, resulting in bigger, healthier infants with better visual alertness.
      • Physical Activity and Strenuous Work: Moderate exercise is generally recommended for low-risk pregnancies, but excessive exertion should be avoided.
    • Drug Intake:
      • Thalidomide: a tranquilizer initially used to alleviate morning sickness but banned due to its association with stunted or missing limbs, facial deformities, and organ defects in infants.
      • Alcohol: Prenatal alcohol exposure is a leading cause of mental retardation and birth defects in the US.
      • Fetal alcohol syndrome: a combination of mental, motor, and developmental abnormalities caused by excessive alcohol consumption during pregnancy.
      • Nicotine: Maternal smoking during pregnancy is a significant factor in low birth weight in developed countries, increasing the risk by more than 1.5 times.
      • Caffeine: High caffeine intake (4+ cups of coffee daily) during pregnancy may elevate the risk of sudden infant death.
      • Marijuana: Heavy marijuana use can lead to birth defects, low birth weight, withdrawal symptoms, and an increased risk of attention disorders and learning problems later in life.
    • Maternal Illnesses:
      • Acquired Immune Deficiency Syndrome (AIDS): a viral disease that compromises the immune system.
      • Rubella (German measles): if contracted before the 11th week of pregnancy, it can almost certainly lead to deafness and heart defects in the baby.

    Stages of Labor

    • Stage 1 (Dilation):
      • The longest stage, lasting 12-14 hours for first-time mothers and 4-6 hours for subsequent births.
      • The cervix dilates from 0 to 10 centimeters in diameter.
      • The amniotic sac ruptures, releasing amniotic fluid.
      • Contractions become more frequent, longer, and stronger.
    • Stage 2 (Expulsion or Delivery) :
      • This stage starts when the baby’s head begins to move through the cervix into the vaginal canal and ends with the baby’s complete emergence from the mother’s body.
      • It typically lasts from a few minutes to several hours.
      • The baby’s body enters the vaginal canal and is delivered.
    • Stage 3 (Placental Stage)
      • Lasts between 10 minutes and 1 hour.
      • The placenta and remaining umbilical cord are delivered.

    Vaginal vs. Cesarean Delivery

    • Vaginal delivery: the standard method of childbirth.
    • Cesarean delivery: surgical removal of the baby from the uterus. Reasons for a Cesarean section include slow labor, fetal distress or complications, breech position, vaginal bleeding, a baby’s head too large to pass through the pelvis, multiple births, premature infants.
      • Risks of Cesarean Section for the Mother: bleeding, infection, damage to pelvic organs, postoperative pain, potential impact on future pregnancies.
      • Risks of Cesarean Section for the Baby: deprived of the benefits of a normal birth, missing out on the hormone surge that clears the lungs of fluid, mobilizes energy for cells, and directs blood to the heart and brain.

    Physical and Motor Development

    Physical Development Across Stages

    • Infancy:
      • Neonatal period: The first 4 weeks of life, a transition from intrauterine dependence to existence.
      • Average neonate is about 20 inches long and weighs about 7.5 pounds.
      • Neonates can lose up to 10% of their body weight in the first days due to fluid loss.
      • They regain weight by day 5 and return to birth weight by day 10-14.
      • Meconium: greenish-black waste matter formed in the fetal intestine.
      • Fontanels: areas on the neonate’s head where the skull bones do not meet.
      • Lanugo: fuzzy prenatal hair that may be present on some newborns.
      • Vernix caseosa: cheesy varnish, an oily protection against infection, dries within the first few days.
      • Neonates require more oxygen upon birth, with breathing starting upon exposure to air.
      • The Apgar Scale (1 minute and 5 minutes after delivery):
        • Created by Dr. Virginia Apgar
        • Assesses five key areas: Appearance, Pulse, Grimace, Activity, Respiration.
        • Each area is rated 0, 1, or 2, for a maximum score of 10.
        • A 5-minute score of 7-10 indicates a good to excellent state of health, 5-7 means the baby requires help to establish breathing.

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    Biological Development PDF

    Description

    Explore the fascinating process of biological beginnings including fertilization, the formation of a zygote, and the stages of gestation. Understand key concepts such as ovulation, prenatal stages, and gestational age. This quiz covers essential early signs of pregnancy and the definition of pre-term and post-term infants.

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