Unit 3 - Prenatal Development

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Questions and Answers

Which of the following structures is responsible for producing blood cells for the embryo until it can produce its own?

Yolk sac (correct)

Placenta

Chorion

Amnion

During which period of prenatal development does the neural tube form?

Period of the zygote

Period of the embryo (correct)

Period of the fetus

All of the above

What is the primary function of the trophoblast cells?

Protect and nourish the developing embryo (correct)

Develop into the nervous system and skin

Produce the amniotic fluid

Form the embryo's digestive system

Which of the following structures is NOT formed during the second month of prenatal development?

Lungs (A) Signup and view all the answers

At what stage of development does the blastocyst implant in the uterine wall?

8-14 days after fertilization (B) Signup and view all the answers

What is the approximate size of the embryo at the end of the second month of development?

2.5 cm long (A) Signup and view all the answers

Which of the following layers of the embryonic disk becomes the muscles, bones, and circulatory system?

Mesoderm (B) Signup and view all the answers

What does the amnion do?

Cushions and regulates temperature (C) Signup and view all the answers

What is the primary function of the placenta?

To provide respiration and nourishment for the embryo (A) Signup and view all the answers

What significant developmental change occurs during the second trimester?

Ability to kick is felt by the mother (A) Signup and view all the answers

What is the primary effect of rubella on an unborn child?

Intellectual disability and cardiac defects (D) Signup and view all the answers

When do teratogens have the strongest impact on a developing fetus?

During sensitive periods of rapid development (D) Signup and view all the answers

What is lanugo and when does it appear?

Fine body hair that appears during 5-6 months (A) Signup and view all the answers

During which stage of pregnancy is toxoplasmosis most harmful to the unborn child?

First trimester (C) Signup and view all the answers

At what point can syphilis begin to impact the unborn child?

18th week of development (C) Signup and view all the answers

At what stage can an ultrasound determine the sex of the baby?

Third month (C) Signup and view all the answers

What is a potential effect of genital herpes on an unborn child?

Neurological disorders and blindness (D) Signup and view all the answers

What significant event occurs during the third month of development?

Embryo can swallow and urinate (B) Signup and view all the answers

What does the age of viability refer to?

22 to 28 weeks, when the fetus can survive outside the uterus (A) Signup and view all the answers

What impact can HIV/AIDS have on an unborn child in developing countries?

Low birth weight and impaired development (A) Signup and view all the answers

What is the structural abnormality caused by thalidomide known as?

Phocomelia (C) Signup and view all the answers

What is vernix and when does it typically appear?

A protective coating for the fetus appearing at 5-6 months (B) Signup and view all the answers

What condition is associated with heavy alcohol consumption during pregnancy?

Fetal alcohol syndrome (FAS) (C) Signup and view all the answers

How do children with fetal alcohol spectrum disorder (FASD) compare to children with ADHD regarding self-regulation?

They have worse self-regulation skills (C) Signup and view all the answers

What are the effects of fetal alcohol exposure?

Poor motor skills and attention problems (A) Signup and view all the answers

What impact does cigarette smoking during pregnancy have on the child?

Slows growth of the fetus and may lead to low birth weight (D) Signup and view all the answers

Which of the following is a consequence of cocaine use during pregnancy?

Increased risk of premature birth (D) Signup and view all the answers

What can happen to a child born to a mother who used heroin during pregnancy?

May be born with addiction and could possibly recover (A) Signup and view all the answers

What is a possible effect of radiation exposure on an unborn child?

High exposure may cause death or intellectual disabilities (C) Signup and view all the answers

What maternal nutrient deficiency can lead to congenital hypothyroidism?

Lack of Iodine (B) Signup and view all the answers

Which age group of mothers is linked to higher risks during pregnancy?

Teen mothers under 20 and older mothers over 35 (C) Signup and view all the answers

How can maternal stress affect the unborn child?

Linked to ADHD and lower birth weight (D) Signup and view all the answers

Study Notes

Prenatal Development

Period of the Zygote: From conception to implantation in uterine wall
Period of the Embryo: Weeks 3 to 8
Period of the Fetus: Weeks 9 to birth
Zygote Timestamps: Single-cell mature ovum released from the ovary on days 9-16 of menstrual cycle; fertilization occurs within 24 hours; 2 cells at 36 hours, 4 cells at 48 hours, 16-32 cells at 72 hours; cell division forms inner cell mass at 4-5 days; blastocyst attaches to uterine wall (8-14 days).
Blastocyst: Ball of cells formed when fertilized egg begins dividing; inner layer is the embryonic disk, which becomes the embryo; outer layer is trophoblasts (protects and nourishes embryo).
Implantation: Blastocyst attaching to uterine wall
Embryo Period: Formation of three cell layers (ectoderm, mesoderm, endoderm); ectoderm forms the nervous system, skin, and hair; neural tube develops from ectoderm (central nervous system); mesoderm forms muscles, bones, and circulatory system; endoderm forms digestive system, lungs, and vital organs.
Significant Event (Week 4): Heart starts beating.
Significant Events (Second Month): Ears, beginnings of skeleton, limbs develop.
Embryo Size (Second Month): 2.5 cm long, 7g
Support Structures (Post-Implantation): Amnion (watertight membrane) surrounds and cushions embryo and yolk sac, produces blood cells until the embryo develops its own blood cell production; chorion surrounds amnion and attaches to uterine tissue for nourishment and waste elimination; placenta forms from lining of chorion and uterine tissue for respiration, nutrition, and waste elimination; umbilical cord connects embryo to placenta to deliver oxygen.
Third Month Development: Able to kick; twist; swallows; digests; urinates; male testes secrete testosterone; size 7.5 cm long; 28 g.
Second Trimester (Months 4-6): Refined motor skills (suck thumb); mother feels the kicks; heartbeat, eyebrows, eyelashes, and hair appear; covered in vernix and lanugo.
Vernix: White substance coating fetus to prevent chapped skin (appears 5-6 months).
Lanugo: Fine layer of body hair allowing vernix to stick to fetus's skin (appears 5-6 months).
Third Trimester (Months 7-9): Organ systems mature; weight gain; age of viability (22-28 weeks), possible survival outside uterus; fetus moves to head-down position; size 48-53 cm; 3.2-3.6 kg.

Teratogens

Environmental Agents: Substances or conditions that can harm developing fetus (viruses, drugs, chemicals, radiation).
Critical Phase of Pregnancy: When particular structures form and grow rapidly; most teratogens have strongest impact during this phase.
Rubella: Maternal disease that can cause blindness, deafness, and cardiac effects in the unborn child. Risk greatest during first trimester.
Toxoplasmosis: Maternal disease caused by a parasite (present in raw meat, cat feces); causes eye and brain damage; risk highest in first trimester.
Syphilis: Sexually transmitted disease; can harm the unborn child. Risk increases as pregnancy progresses; miscarriage possible.
Genital Herpes: Sexually transmitted disease; brain damage and neurological disorders possible during birth or contact.

Other Prenatal Development Factors

Thalidomide: Mild tranquilizer; causes limb malformations.
Diethylstilbestrol (DES): Synthetic hormone; linked to cervical cancer and genital abnormalities in female children.
Fetal Alcohol Spectrum Disorder (FASD): Congenital problems resulting from alcohol consumption; self-regulation and intellectual development problems. (worse ADHD)
Fetal Alcohol Syndrome (FAS): Severe version of FASD; microcephaly, facial malformations, hyperactivity, seizures, and low average intelligence.
Fetal Alcohol Effects (FAE): Mild version of FASD; motor skills and attention problems are below average intellectually
Cigarette Smoking (Pregnancy): Slows fetal growth; lower birth weights; cleft lip and palate; miscarriage or stillbirth risk.
Cocaine Use (Pregnancy): Premature birth; smaller babies; lower IQ
Heroin Use (Pregnancy): Increased neonatal death rate; newborns may be addicted.
Marijuana Use (Pregnancy): Emotional, behavioral, and academic problems in the child.
Radiation Exposure (Pregnancy): Physical deformities, intellectual disabilities, or death.

Recommendations and Safeguards

Recommended Weight Gain (Pregnancy): 11-14 kg
Iodine Consumption (Pregnancy): Crucial; deficiency linked to congenital hypothyroidism and cretinism.
Folate (Folic Acid) Consumption (Pregnancy): Necessary for neural tube development; deficiency linked to spina bifida and anencephaly.
Stress (Pregnancy): Linked to negative effects on the unborn child; prenatal growth stunting and lower birth weight are possible
Maternal Age: Teen mothers (under 20) and mothers over 35 years of age experience heightened risks.
Environmental Toxins: Pregnant woman and partner should attempt to limit exposure to environmental toxins.
Safest Time Frame to Have Children: 20-35 years.

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Description

Explore the fascinating stages of prenatal development, from conception to birth. This quiz covers the periods of the zygote, embryo, and fetus, along with key processes like implantation and cell layer formation. Test your knowledge of the biological changes that occur during this critical phase of human development.