Prenatal Development and Early Movement

Flashcards covering the stages of prenatal development, system changes from conception to birth, fetal circulation bypasses, and environmental/genetic influences on fetal motor and structural growth.

What is the approximate duration of human gestation in weeks and days?

$40$ weeks +/- two weeks, or approximately $280$ days.

How are pre-term and post-term pregnancies defined by gestational weeks?

Pre-term is defined as <$37$ weeks; post-term is defined as >$42$ weeks.

What are the three periods of the Gestational Period and their specific timeframes?

Pre-embryonic ($0-2$ weeks), Embryonic ($2-8$ weeks), and Fetal Period ($9$ weeks to birth).

What are the timeframes for the trimester system in prenatal development?

1st trimester = $1-13$ weeks; 2nd trimester = $14-26$ weeks; 3rd trimester = $27-39$ weeks.

Where does fertilization typically occur and what is the resulting cell called?

It occurs in the Fallopian tubes and the resulting cell is a zygote.

During the pre-embryonic period, what is the term for the rapid cell division occurring from $0-2$ weeks?

Cleavage.

By approximately which day does implantation on the uterine wall occur?

$7^{th}$ day.

What are two specific implantation abnormalities mentioned in the notes?

Ectopic/tubal pregnancy and Placenta previa.

What major systems or tissues develop from the Ectoderm germ layer?

Nerve system and skin.

What major systems or tissues develop from the Mesoderm germ layer?

Muscle, bone, heart, and connective tissue.

What major systems or tissues develop from the Endoderm germ layer?

GI, lungs, and urinary system (non-muscular).

What key anatomical structures appear during Week $4$ of the Embryonic Period?

Heart, neural tube, eyes, ears, and limb buds.

What changes occur in the heart and sex assignment during Week $7$ of the Embryonic Period?

The heart becomes a $4$ chambered organ and the fetus is assigned sex.

Describe the function of the Umbilical Vein and the (2) Umbilical Arteries in fetal circulation.

The Umbilical Vein carries Oxygen ($O_2$) and nutrients from mother to fetus; Umbilical Arteries carry waste products from fetus to mother.

Name the three fetal bypass systems and their functions.

Ductus Venosis (liver bypass), Foramen ovale (Right to Left atrium), and Ductus Arteriosis (from right ventricle to pulmonary trunk to descending aorta).

What early reflexes appear during weeks $9-12$ of the Fetal Period?

Grasp, suck, swallow, blink, and withdrawal.

When is the first 'age of viability' and what is the typical weight at $24$ weeks?

The age of viability is approximately $23$ weeks; weight at $24$ weeks is $720/g$.

At what gestational age does the suck/swallow ability reach maturity?

$35$ weeks.

When does early fetal movement begin and when does spontaneous movement start?

Early movement begins at ~$7-8$ weeks; spontaneous movement begins at ~$12$ weeks.

What is the distinction between critical periods for structural vs. functional abnormalities?

Embryonic development ($2-8$ weeks) is critical for structural abnormalities; Fetal development ($8$ weeks to term) is critical for functional and minor abnormalities.

What is a teratogen and what are two specific medication examples?

A substance known to cause physical defects in the embryo; examples include Thalidomide and Streptomycin.

How much daily caloric intake is required for an individual who is pregnant?

Approximately $3000$ cal/day.

What infection is associated with microcephaly if contracted during pregnancy?

Zika virus.

Explain the biological pathway of maternal stress affecting the fetus.

Stress releases Adrenaline (increasing fetal activity) and Cortisol (negatively influencing fetal development), which travel through the placenta to fetal circulation.

What infection, often associated with raw meat or kitty litter, can cause CNS lesions and blindness?

Toxoplasmosis.