Chapter 4 - Prenatal Development and Birth Flashcards
The Stages of Prenatal Development
Zygote Stage (Week 1- 2)
Embryonic Period (Weeks 3-8)
Fetal period (Weeks 9-38)
Zygote Stage
Week 1- 2
Begins as fertilized egg
Starts to separate into fetus and placenta
- Germ disc (fetus cells)
Moves down the fallopian tubes toward uterus
Implants into uterine wall
Starts to secrete hormones (HCG) that prevent menstruation
Embryonic Period
Weeks 3-8
Ectoderm
Mesoderm
Endoderm
Fetal Period
Weeks 9-38
Bodily systems start to work
Large shift in size
Risks to Prenatal Development
Nutrition
* Balanced
* Folic acid
Stress
* Early
* Chronic
Age
* < 20
* > 40
Teratogens:
Diseases, Drugs, and Environmental Hazards
Teratogens: Drugs
Slow growth
Heart problems
Cognitive delay
Poor social judgement
Limited motor skills
Teratogens: Diseases
Transferred through:
- Placenta
- Birth canal or exposure during birth
Prevention - vaccines
Teratogens: Environmental Hazards
Grassy Narrows First Nation
Water pollution
Mercury in fish
Intergenerational effects
Teratogens
- Teratogens interact
with genotype - Timing of exposure
matters - Damage is selective
- Damage may not be
obvious at birth
Prenatal Diagnosis
Amniocentesis
Chorionic Villus Sampling
Birth Complications
Lack of oxygen
Low birth weight
Prematurity
Placenta
A structure for exchanging nutrients and wastes between the mother and the baby
Cephalocaudal Principle
Grows from the top down
Proximodistal Principle
Grows from the center out
When does the brain/spine grow?
After 4 weeks, a flat set of cells curls to form a tube. One end swells to form the brain, the other forms the spinal cord
During the period of the fetus, all regions of the brain grow , particularly the cerebral cortex
When do testes/ovaries grow?
Near the end of the embryonic period males develop testes and females develop ovaries
When does hair/eyelashes grow?
In the 5/6 months
Then covered in a thick substance called vernix which protects the fetus in the amniotic fluid
The Age of Viability
22-28 weeks, most likely will survive if born at this time
The Optimal Age for Having Children
Between 25-34 years
Typical Fetus Age for Birth
38 weeks
Cervix
The opening, entry to the birth canal
The Apgar Score
Virginia Apgar
Used to evaluate the newborn baby’s condition
Look for breathing, heartbeat, muscle tone, reflexes (eg, coughing, crying), and skin tone
4 Newborn States
Alert Inactivity
Waking Activity
Crying
Sleeping
