Chapter 4 - Prenatal Development Flashcards by Jess Black

How long are each trimester?

about 4 months

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When can you tell someone is pregnant?

around month 5

most families wait to announce until second trimester since chances of random abortion are much lower

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What trimester has morning sickness?

first

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What is the germinal period? (period of the zygote)

from conception to implantation of the uterine wall

first 2 weeks

going through mass cell division to form blastocyst
- mitosis and meiosis

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What is the period of the embryo?

week 3-8

zygote begins to take form of human

once implanted, begin to develop support structures
- amnion, chorion, placenta, umbilical cord

3 cell layers will form rapidly

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What forms the placenta? What is its role?

the uterine wall

extremely important - how the baby gets its food and gets rid of waste

many complications around placenta

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What is the amnion?

membrane around the embryo for temperature regulation and protection

filled with amniotic fluid from maternal tissue

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What is the umbilical cord?

connect placenta to belly button of embryo

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What is the chorion?

membrane that attaches to uterine tissues to gather nourishment for embryo

becomes placenta lining eventually

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What is the indifferent gonad?

everybody develops the same gonad, Y chromosome triggers reaction to produce testes which produce testosterone

no reaction = ovaries

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What are the 3 cell layers that form in the period of the embryo?

ectoderm
- NS (neural tube), skin, hair

mesoderm
- muscle, bone, circulatory system

endoderm
- digestive system, lungs, urinary tract, other vital organs

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What happens if a brain fails to form?

encephaly

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What are the key outcomes of the second month? (still in period of the embyro)

rudimentary formation of:

facial features
skeleton and limbs

brain rapidly develops

indifferent gonad appears

about 2.5cm and 7g

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When is the period of the fetus?

week 9-month 9

half of first trimester plus entire 2nd and 3rd

becomes recognizable as human

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What is happening in weeks 9-12?

organs rapidly develop

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What is happening in weeks 13-24?

movement begins

react to stimuli

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What is happening in weeks 25-38?

maturation

regular sleep cycles
- lots of sleep in last 2 weeks

assume fetal position

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What are key developmental outcomes in month 3?

able to move but not felt by month

can swallow, digest, urinate

testosterone secreted by testes in male or female genitalia form
- ultrasound can determine sex

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What are the key developmental outcomes in the second trimester?

more refined motor actions
- thumb sucking

kicking may be felt by mother

heartbeat can be heard with stethoscope

hair growth appears

visual and auditory senses clearly functional
- can discriminate between sounds

form vermix (protective coating) and lanugo (baby hair)

What are the key developmental outcomes of the 3rd trimester?

“finishing phase”

organ systems mature rapidly

weight gain

age of viability at 22-28 weeks

9th month: move head down with limbs curled (fetal position)

birth!

48-53cm, 3.2-3.6 kg

What is the age of viability?

22-28 weeks

when survival outside the uterus becomes possible

What are teratogens?

environmental factors that affect prenatal development and harm developing fetus

ex. virus, drugs, chemicals

What is a sensitive period?

time when each developing structure is particularly susceptible to damage form teratogens
- recall rapid development during embryonic period - likely most susceptible here

once parts are fully formed, less susceptible to damage

What are environmental hazards? How can the fetus be exposed?

radiation
chemical
pollutants

direct exposure to mother/fetus
indirect exposure from father
- changes chromosomes

What is the recommended weight gain for mothers? Why?

11-14 kg malnourishment results in small babies - may disrupt spinal cord development in 1st trimester - leads to low birth weight in 3rd trimester

What vitamin is crucial for neural tube development?

folate/folic acid deficit can cause spina bifida

How does the mother's emotional well-being affect the fetus?

stress = decreased birth weight = birth complications

How does parental age affect the fetus?

risks associated with teen mothers as well as older parents

When is rubella exposure most dangerous? What are the effects?

most dangerous in 1st trimester blindness, deafness, cardiac abnormalities. mental retardation

What is toxoplasmosis? What are the effects?

parasite acquired from undercooked meat or handling feces from cat - pregnant women should never change cat litter effects are cold-like symptoms in adults, but include eye and brain damage in fetus, even miscarriage thereafter

What is thalidomide? What are the effects?

originally marketed to relieve morning sickness but effects very harmful when taken early in pregnancy severely deformed organs, limbs, facial features Thalidomide tragedy gave thousands of women's babies these symptoms

How does cigarette smoking affect the fetus?

slows fetus growth - associated with low birth weight cleft lip, abnormal lung function higher incidence of ectopic pregnancy possible cognitive deficits

What is FASD?

fetal alcohol spectrum disorder FAS and FAE

What is FAS?

fetal alcohol syndrome caused by heavy drinking microencephaly, malformation, hyperactivity, seizures, below average intelligence and size

What is FAE?

fetal alcohol effects caused by moderate social drinking poor motor skills, attention issues, below average intelligence

What are the effects of illicit drugs on the fetus?

marijuana - emotional, behavioural, academic problems heroin - neonatal death, addicted at birth crack/cocaine - premature birth, low IQ

What is considered to be prenatal development?

development that occurs between the moment of conception and the beginning of the birth process

What is the blastocyst?

ball of cells formed when fertilized egg first begins to divide inner layer becomes embryo, outer layer becomes protective/nourishing tissues

How does implantation occur?

tendrils emerge from blastocyst and burrow into uterine wall, tapping maternal blood supply takes about 48 hours looks like small blister

What are the odds of implantation being successful?

only 1/2 of fertilized ova are firmly implanted, nearly 1/2 of these are genetically abnormal or fail to develop 3/4 fail to survive initial phase of development

What is the placenta?

site of all metabolic transactions from embryo to mother carries O2 and nutrients, removes CO2 and metabolic waste villi prevent blood from mixing

What is the vermix?

white cheesy substance that protects fetus skin from chapping

What is lanugo?

fine hair covering fetus body to help vermix stick to skin

What is the purpose of the uterus contractions over the last month of pregnancy?

tone the uterine muscles dilate the cervix help position head in gaps between pelvic bones

What are sleeper effects?

teratogenic effects that may not be apparent until later in life

What STD infections are transmitted to the newborn at birth?

genital herpes

What is the most common preventable cause of intellectual disability?

FASD