Genetics, Conception, Fetal Development Flashcards
1
Q
Chromosomal Abnormalities
A
- A major cause of reproductive loss, congenital problems, and gynecologic disorders
- Can occur during mitosis (somatic cells) or meiosis (sex cells)
> chromosome #: down syndrome
> a single gene controlling a trait, disorder, or defect
> sex chromosome abnormalities
2
Q
Clinical Genetics - Multifactorial
A
- Most common genetic malfunction
- Combination of envir’t and genetic factors
> cleft lip/palate
> congenital heart disease
> neural tube defects
> pyloric stenosis
3
Q
Genetic Counseling
A
- Standard practice in obstetrics
- Goal is to identify risk
- Genetic hx should be obtained using a questionnaire or checklist
- Genetic counseling
> info
> education
> support
4
Q
Conception
A
- Fertilization
- Cleavage - 1 day
- Morule - 3 days
- Blastocyst - 4 days
- Implantation - 6 days
5
Q
Process of Implantation
A
- Endometrium becomes thick and vascular
- Decidua after implantation
> trophoblasts make contact w/ endometrium
> maternal side of placenta develops - Morula and blastocyst develop trophoblast
> becomes chorion
> chorion produces HCG
> chorionic villi develop out of trophoblas and extend into blood-filled spaces of endometrium
6
Q
Intrauterine Development
3 stages
A
-
Ovum or Preembryonic Stage
> conception - 14 days -
Embryonic Stage
> day 15 - 8 weeks gestation
> most critical time; teratogens -
Fetal Stage
> 9 weeks - birth
7
Q
Intrauterine Structures
A
-
Yolk sac
> aids in transferring maternal nutrients & oxygen -
Umbilical cord
> supplies the embryo w/ maternal nutrients & oxygen
8
Q
Chorion & Amnion Membranes
A
- The 2 layers of amniotic sac
- Functions:
> provides space for movement & growth
> maintains consistent temperature
> protects from pressure/impact
> barrier against ascending infection
> cushions umbilical cord
> composed of water secreted by amnion & fetal urine
9
Q
Amniotic Sac & Fluid
A
- Incrs during pregnancy and peaks at 38wks, then starts to dcr
- Important factor in assessing fetal well-being
-
Normal range of AFI = 5-20cm on U/S or 300-2000mL
> less than 300mL = oligohydramnios; concerning for renal abnormalities
> greater than 2000mL = polyhydramnios; concerning for gastrointestinal tract abnormalities
10
Q
Placenta Structure
A
- Maternal>placental>embryonic circulation by day 17
- Functional unit of placenta divided into 15-20 cotyledons
11
Q
Placenta Function
A
- Endocrine gland (hCG, human placental lactogen, & estrogen)
- Metabolic func & waste
- Nutrient storage
12
Q
Fetal Circulatory System
A
- Cephalocaudal formation
> most oxygen-rich blood circulation in head, neck, & arms - 3 characteristics for sufficient oxygenation:
> fetal Hgb 20-30% more oxygen than mom
> Hgb concentration 50% greater than mom
> FHR 110-160, cardiac output per unit body weight higher than an adult
13
Q
Fetal Maturation
hematopoietic syst
renal syst
respiratory syst
A
-
Hematopoietic
> formation of blood occurs in the yolk sac -
Renal
> urine = major constituent of amniotic fluid -
Respiratory
> primary surfactants: prevents lung collapse during exhalation and reduces lung surface tension making breathing easier
> also used as a measure of fetal lung maturity: lecithin to sphingomyeline ratio 2:1
14
Q
Fetal Maturation
gastrointest syst
hepatic syst
A
-
Gastrintestinal
> fetal nutrition & elimination is taken care of by placenta -
Hepatic
> prominent liver for blood production
15
Q
Fetal Maturation
neurologic
endocrine
A
-
Neurologic
> stressors on fetus & neonate can damage CNS long after embryonic stage
> sensory awareness (taste, sounds, purposeful movements) -
Endocrine
> thyroid develops in 1st few weeks as head develops; maternal thyroxine does not cross placenta
> pancreas forms in mid-1st trimester
