Lec. 2 - Fetal Development

chromosomes

major cause of gene loss, gynecological disorders, congenital problems

• occurs during mitosis or meiosis

• patterns of transmission - unifactoral/multifactoral

inheritance

• each gene is coded for inheritance

• carry instructions fro dominant and recessive genes

sex determination

XY chromosomes determine gender

• XX - female

• XY - male

meiosis

• undergoes 2 divisions cutting chromosomes from 46 to 23 total

• gamets split undergoing gametogenesis

zygote

result of sperm penetrating and uniting with ovum

• in outer 3rd fallopian tube near ovaries

• once in causes chemical change in membrane preventing other sperm entry

• survives in cervix up to 5 days

• sperm itselfs typically lives fro 2-3 days

• ovum can be fertilized 24hrs prior to regeneration and resorption

chorion

develops from trophoblasts and envelopes, amnion, embryo and yolk sac

• villi extend into decidua basilas on uteran wall to develop embryonic/fetal portion of placenta

Amnion

the second membrane

• thin structures protects embryo

• form with chorion to from sac filled with fluid

amniotic fluid

5 functions:

• maintain even temperature

• prevent amniotic sac form sticking to fetal skin

• allows symmetrical growth

• allows bouyancy and fetal movement

• acts as cushion protects cord, fetus form injury

yolk sac

cavity develop son 9th day after fertilization

• fxn only during embryonic life

• initiates RBC production

• continues until fetal liver takes over (6wks)

• umbilical cord encompasses yolk sac which degenerates

Primary Germ Layers - Endoderm

• lining of trachea, pharynx, bronchi

• lining of digestive tract

• linigns of bladder, urethra

primary germ layers - Mesoderm

• true skin

• skeleton

• bone and cartilage

• connective tissue

• muscles

• blood and blood vessels

• kidney and gonads

primary germ layers - ectoderm

• outer layer of skin

• oild glands, hair follicles of skin

• nail and hair

• external sense organs

• mucous membrans of mouth and anus

Placenta

organ for fetal respiration, excretion and nutrition

placental transfer - fetal deoxygenated blood/waste products leave fetus through 2 umbilical arteries

fetal and maternal blood do not typically mix

• oxygenated nutrient rich blood from mom go to intervillus space from spacial arteries in diciduai

• fetal blood release CO2/waste, and take O2 and nutrient before returning to fetus through umbilical vein

• harmful substance can transfer to fetus (drugs, nic, viral infxn agents)

umbilical cord

life line between mother and ftus

• 2 arteries away, 1 vein back to fetus

placental hormone - progesterone

maintain uterine lining for zygote

• reduce Ucs prevent spontaneous abortion

• prepares breast glands for lactation

• stim. testes produce testosterone

• aids development of reproduticve tract

PLacental hormones - Estrogen

• stimulates uterine growth

• inc. blood flow to uterine vessels

• stim. development of breast duct to prepare lactation

placental hromones - hCG : human chorionic gonadatropin

signals corpus luteum that conception occured

• basis of most preg tests

• detectoible 7-9days after arresst

placental hormones - Human placental lactogen

cause dec. insulin sensitivity and utilization of glucose by mother to make more glucose

Fetal circulation shunts - ductus venosus

first shunt

• after the umbilical vein and live

• avoid liver to go to inferior vena cava and then R atrium

fetal circulation shunts - Foramen ovale

2nd shunt after the R atirum that leads directly to left atrium and then L ventricle

• skips R ventricle and Pulmonary arteries

fetal circulation shunts - ductus arteriosus

3rd shunt

after the R ventricle and Pulmonary arteries

• skips to aorta to fetal body and umbilical arteries

fetal circulation

shunts close after birth

• placenta send Oxygenated blood to umbilical vein then liver

• umbilical liver → ductus venosus → inf ven cava → R atrium → R ventricle → pulm arts → lungs → pulm veins → L atrium → L ventricle → aorta → fetal body → umbilical arteries → placenta

Teratogens

something tha can cause a birth defect, abnormalities in developing embryo or fetus

• exposure comes from ingestion or environmental atmospheres

ex: meds, drugs, tobacco, chemical, alcohol, infxns, health problems like diabetes

Nonteratogenic agents

• spermicides, acetominophens, prenatal vitamins

teratogens - timeline

• 10-14 days affect developing embryo

• 3.5-4.5 weeks - neural tube defecets

• 20 weeks - chickenpox can result in cogenital varicella syndrome

• near delivery - chickenpox can cause neonatal vericella

Abortion

termination of pregnancy before viability (20weeks)

• several types: theatened, incomplete, complete, inevitable, missed, recurrent

ectopic pregnancy

fertalized egg implants and begins growing outside uretherin cavity

Hydantiform mole

gestational trophoblastic dz

• abnormal pregnancy from abnormal fertalization resulting excessive growth trophoblastic tissue and little or no normal fetal development

Abortion interventions - Meds

• pitocin

• rhogam

• methotrexate

• prostoglandanins

• hypertonic uterine infusions

• cytotec

• miferpristone

abotion interventions - Medical tx

• ultrasounds

• bedrest

• cerclage

• D and E

• vaccum extraction

abotion interventions - nursing interventions

• document

• amount/character of bleeding

• monitor vitals fro hypovolemic shock

  • labs

abotion interventions - s/sx

• vaginal bleeding

• abdominal cramping

• low back pain

• pass tissue or clots

• dec. pregnancy symptoms

• dilated cervix

extopic pregnancy interventions - Medications

meds to control blood loss

extopic pregnancy interventions - Medical tx

• HCG lvls

• culdocentesis

• no action

• methotrexate if tube not ruptured

• surgery to remove tube

• remove tube

ectopic pregnancy interventions

• abd pain = delyaed menses

• abnormal vaginal bleeding

• lower ABD pain w/o bleeding

• tubual rupture - sudden severe lower abd pain

• hypovolemic shock

• shoulder pain

molar pregnancy - medical tx

• may pass spontaneously

• D and E

• HCG testing for 1 yr

• Rhogam

molar pregnancy - Nursing interventions

• monitor bleeding

• provide resources for grief counseling

• pt. education, contraceptive

• delay conceiving 1x yr

molar pregnancy - other

• bleeding

• rapid uterine growth

• fail detect FHR

• s/s hyperemesis G

• early development of gestational HTN

patient edu. for all types of abortions

• report inc. bleeding

• temp Q8 for 3 days

• Fe supp.

• no tampons

• resume sex as recommended by PCP

• follow up apt

• support groups

emotional support

what to do after

acknowledg the loss

• avoid minimizing statements