Lecture 36- Fetal Period Flashcards by Raghad Raghad

What is the first organ system to function?

Cardiovascular system (heart forms and begins to beat at week 4)

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What happens at week 5-8?

Limbs start becoming clear, heart 4 chambered
Bone formation begins
External genitalia begins to differentiate

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Fetal period is mainly characterized by?

Body growth

Maturation of of organs

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Embryonic period is mainly characterized by?

Tissue differentiation
Formation of organs
Rapid body growth

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What is the earliest period the fetus can be born prematurely and live?

Week 25+

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What happens in week 9-12

Fetal length nearly doubles
Heartbeat can be detected
Gender can be assessed by looking at external genital

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When does the fetus assume upside down position?

Week 30-34

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What is the body fat % of fetus before birth?

16% (8% in weeks 30-34)

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What is the weight of fetus before birth?

3200-3400g

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Placenta is a fetomaternal organ with 2 components
Fetal (develops from x)
Maternal (develops from y)

Fetal develops from villous chorion

Maternal develops from decidua basalis (part of endometrium lining)

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As the fetus grows,the chorionic cavity x, and for amniotic cavity y, degrading thr

The chorionic cavity disappears, and the amniotic cavity expands, degrading the desidua capsillaris

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What is the primary function of the placenta?

Serve as an organ for exchange between the concepts and mother

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Do the maternal and fetal blood directly mix?

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Give eg’s of nutrients that enters the fetus from the endometrial spiral arteries

Water
Carbs (glucose)
Amino acids
Lipids
Electrolytes
Harmones 
Vit’s
Iron

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Give ex’s of substances that leave the fetus through the umbilical arteries

Waste products like:
CO2
Water
Urea
Uris acid
Bilirubin
Other substances:
RBC antigens 
Harmones

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T/f the umbilical arteries carry oxygenated blood from the fetus’s heart to the chorion

False

The umbilical arteries Carry DEOXYGENATED blood

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What’s the function of HcG harmone?

It is a harmone secreted by the placenta
Rescues the corpus luteum so that it continues to produce progesterone and some estrogen to
Maintain endometrium lining 
Prepare mammary glands for lactation 
Prepare mother’s body for birth

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What is the function of relaxin?

A harmone secreted by the placenta

Increases flexibility of the pubic symphysis (easier to undergo labor)
Helps dilate the uterine cervix during labor

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What is the funding

Function of Human chorionic somatomammotropin hCS

Helps prepare the Navarre glands for lactation
Enhances growth by increasing protiens synthesis
Decreases glucose used by the mother and increases fat acid use by mother for ATP ( leave glucose to the fetus)

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What is the function of Corticotropin releasing harmone?

Establishes the timing of birth

Increases section of cortisol TO MATURE THE LUNGS!

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Describe the placenta

A discoid structure with a diameter of 15-25cm
Thickness of about 3cm
Weirgr 500-600gm
Maternal side exhibits 15-20 cotyledons (bumpy part) separated by decidual septa
Fetal surface covered by amnion

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When is the placenta expelled?

Approx 30 min after birth

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What is placenta previa?

Placental abnormality where the placenta is implanted lower end of the uterus (close to cervix)
Birth will be very bloody; C section os usually advised

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What is placenta accreta?

Placental abnormality where the villi will adhere superficially to the muscle wall (myometrium)

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What is placenta percreta?

Placental abnormality where the placenta adhered DEEP into myometrium

The amount of amniotic fluid gradually increases during pregnancy. Usually from s ml at week 12 to ml at term

50ml at week 12 | 1000ml at term

What’re some of the contents of the amniotic fluid?

``` Electrolytes Carbs A acids Lipids Proteins Harmones Enzymes A-fetoprotein Urea Desquamated fetal cells Fetal urine Fetal feces (meconium) Fetal lung tissue ```

Amniotic fluid is constantly being produced | How is there inflow and outflow?

Inflow directly from maternal circulation in response to osmotic forces Fluid content also increases by secretion of urine by the kidneys into the amniotic sac Outflow: fetus swallows amniotic fluid AF is absorbed into fetal blood through GIT Excess AF is removed via placenta and passed into maternal blood

What can lead to polyhydraminos? | And what is volume of amniotic fluid typically needed to diagnose this illness?

``` Swallowing defects (esophageal atresia or amenecephaly) Absorption defects (duodenal atresia) 2L+ ```

When does the amnion enlarge to the point of obliterating the chorionic cavity?

Week 8

What is the function of AF?

Permits symmetrical growth of thr embryo or fetus Acts as a barrier to infection Prevents adherence of amnion to embryo and fetus Permits normal fetal lung development (corticotropin releasing harmone) Cushions the embryo/fetus Enables movement of fetus to aid in muscle development Maintains homeostasis

Oligohydraminos is having less that xml of amniotic fluid | What May cause oligopolyhydraminos?

400ml and below | Renal agenesis May cause oligohydraminos (no urine secretion to AF)

The umbilical cord at term is what color? Diameter, and length? Contains how many umbilical arteries and veins?

``` Pearl white 1-2cm in diameter 50-60cm long 2 umbilical arteries 1 vein ```

What is Wharton jelly?

Mucus connective tissue of the umbilical cord

Monozygotic twins will have resemblance in development to dizygotic twins if...

Splitting occurs at the 2 cell stage

If splitting of monozygotic twins is at blastocyst stage (2 inner cell masses) embryos will have x chorion and placenta, and have y amnion

If splitting occurs at blastocyst stage (2 cell masses) There will be a single chorion and placenta, But seperate amnion

If splitting occurs AFTER the formation of the inner cell mass, the embryos Will have how many amnion?

Just one amnion that will be shared

How common are birth defects?

1/16 of live births

What is the critical period (when the embryo is most at risk of abnormal development)?

During embryonic stage (3-8 weeks)

Why is the critical period not during early embryonic period?

Because rather than abnormal development occurring, death normally occurs of strong regulation mechanisms prevent abnormalities

What is the major cause of congenital malformations?

Unknown (for 50-60% of cases)

What % of congenital malformations are genetic?

Around 15% 7-8% due to mutant genes 6-7% due to chromosomal abnormalities

What % of congenital malformations is due to multi factorial inheritance?

20-25%

What % of congenital malformations is due to environmental agents?

7-10%

What are the main categories of environmental factors of birth defects?

Infectious agents Physical agents Chemical agents

What congenital malformations can the rubella virus cause?

``` Cataracts Glaucoma Heart defects Hearing loss Tooth abnormalities ```

What congenital malformations can cytomegalovirus cause?

Microcephalic Visual impairment Intellectual disability Fetal death

What congenital malformations can toxoplasmosis cause?

Hydrocephalus Cerebral calcifications Microphthalmia

What congenital malformations can X-rays cause?

Microcephaly Spina bifida Cleft palate Limb defects

What congenital malformations can Thalidomide cause?

Limb defects | Heart malformations

What congenital malformations can Warfarin (anticoagulant) cause?

Skeletal abnormalities (nasal hypoplasia, stippled epiphyses)

What congenital malformations can ACE inhibitors cause?

Growth retardation | Fetal DEATH!

What congenital malformations can alcohol cause?

Fetal alcohol syndrome (low birth weight) Short palpebral fissures Heart defects Intellectual disability

Is Vit A healthy for the Fetus?

NO! Consuming it can cause CONGENITAL MALFORMATIONS! small abnormally shaped ears Cleft palate Heart defects

Maternal diabetics and maternal obesity can cause?

Congenital malformations

What congenital malformations can Androgenic agents cause?

Masculinization of female genitalia Fused labia Clitoral hypertrophy

Why is ultrasound a good technique to assess fetus?

Or is noninvasive Can assess Fetal age and growth Presence or absence of NTD, abdominal wall defects, heart and facial defects Amount of AF Placental position and umbilical blood flow Multiple pregnancies

Why would maternal serum screening be performed?

To assess activity of Alfa-fetoprotein conc The levels are high during week 12- 15 of pregnancy. Then the concentration decreases A high level of AFP after w 16 indicates neural tube defects A low level of AFP indicates Down Syndrome

Amniocentesis

It is an invasive procedure performed performed form 15-20 week of pregnancy Amniotic fluid is withdrawn by a needle through the anterior abdominal wall Squamous fetal cells are cultured for testing purposes (karyotyping analysis can be used to diagnose chromosomal abnormalities) Also assess lung maturity

What is chorionic villus samplingamd when is it indicated?

A non common, slightly invasive procedure that is conducted form weeks 8-12 of pregnancy The tube is inserted through the vagina between the uterus and chorion with the aid of Ultrasound Sample of chorionic villi is taken Can be used]]]

Lecture 36- Fetal Period Flashcards

(60 cards)