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Peri 1,2,3,4, 5
WillWallace Perinatology Ch 1, 2, 3, 4, 5
Question | Answer |
---|---|
perinatology | subspecialty of obstetrics concerned with the care of the mother and fetus at high than normal risk of complications |
types of disorders Perinatologist treat | diabetes, premature labor, perinatal infectious disease, multiple gestation, perinatal pharmacology |
what do perinatologist treat or asses in the fetus | gestational age and growth, evaluation for congenital anomalies, placenta and amniotic fluid and adequacy of uteroplacental function |
where does fertilization take place | outer third of the fallopian tube |
stage 1 aka ovum stage, what happens and how long is it | conception to implantation (12-14 days), |
stage 2 aka embryonic stage, what happens and how long is it | end of ovum until head to rump is 3cm (54-56 days), major organs develop, very vulnerable to drugs, infection etc |
stage 3 aka fetus stage, what happens and how long is it | from embryonic until end of pregnancy, growing |
how long does it take the ovum to reach the uterus | 4-5 days |
what is cleavage | cell division by daughter cells inside the ovum, 1 becomes 2, 2 becomes 4 |
blastomeres | cells produced by rapid cleavage inside the ovum, they are surrounded by a clear envelope called the zona pellucida |
zona pellucida | transparent envelope surrounding the blastomeres |
morula | blastomeres that have grown in numbers to form a ball (16-50 cells) and is what ovum is called as it enters uterus |
blastocyst | fluid builds up inside murula and it is now called blastocyst, has a cavity inside filled with fluid consisting of uterine fluid and fluid excreted by blastomeres |
trophoblast | the new outer layer of the blastocyst, takes the place of the zona pellucida |
what and where are the germ layers | cells inside blastocyst differentiate into 2 layers, endoderm (inside) and ectoderm (outside and thicker), short time later mesoderm forms in between. |
What do the germ layers do | it is from the germ layers that all tissues organs and organ systems will arise |
what arises from the endoderm | respiratory tract, epithelium of the digestive tract, bladder and thyroid, primary tissue of the liver and pancreas |
what arises from the ectoderm | epidermis, hair and nails, lens of the eye, central and peripheral nervous system and the skin glands |
what arises from the mesoderm | dermis, muscles, bone, connective tissue and lymph tissue, reproductive organs and cardiovascular system |
when does the pulmonary system start to develop and when does it end | starts 24 days after conception and ends around age 8 |
what are the 5 stages of lung development | embryonic period (conception-6weeks), pseudoglandular period (7-16 weeks), canalicular period (17-26 weeks), saccular period (27-32/34) alveolar period (32-34 weeks gestation to to 8years) |
lung development during the embryonic period (stage 1) | conception to 6weeks, lung buds appear followed by two branches, airway branches begin, pulmonary arteries perfused developing lung tissue, airways divide |
lung development during the pseudoglandular period (stage 2) | 7-16 weeks, branching continues to term bronchi, muscle, elastic tissue and early cartilage forms in airways, mucus glands formed diaphragm develops |
lung development during the canalicular period(stage 3) | 17-26 weeks, airways increase in length and diameter, airways end in blind pouches, few pulm capillaries present early and proliferate rapidly toward the end of period, alveolar ducts form, type I & II cells, immature surfactant |
lung development during the saccular and alveolar period(stage4-5) | alveoli appear, merging of alveolar epithelium and the pulmonary capillaries, appearance of mature surfactant, alveoli continue to increase in size and number |
what causes surface tension | similar molecules attract each other from all directions, bead of water, or spider to walk on water, constant inward pull of molucules. |
What causes surface tension in alvioli and what does it cause | alvioli are largly liquid filled with gas, liquid is attracted inward due to the attraction causes alvioli to shrink to its smallest diameter |
laplace's law | importance of relationship between internal pressure of a sphere, it's radius and surface tension...as the radius of the bubble (alvioli) decreases, the surface tension increases. |
Apply laplace's law to a balloon and alvioli | small balloon is hard to blow up, but balloon half blown up is easy, same with alvioli, at end exhalation alvioli are small and (would if not for surfactant) require > energy and work to inflate the lungs |
surfactant | substance found in alvioli wall that reduces surface tention, unique composition and fact that it remains stable in the alveoli, allows it to exert varying influence on alveoli as they enlarge and shrink |
what is the importance of the varying influence of surfactant on alveoli | as alveoli increase in size, surfactant thins and tension builds, aiding passive ventilation, as alveoli shrink, surfactant thickens weakening surface tension and preventing alv from collapsing |
where is surfactant produced | type II cells |
what is surfactant made of | phospholipids, mainly phosphatidylcholine (PC) and phosphatidyglycerol (PG), neural lipids and protein, since first surfactant only has PC, it is considered immature until PG is present around week 35 |
babies born befor 30 weeks are especially prone to what disorders | hypoxia, hypothermia and acidosis |
hypoxia, hypothermia and acidosis cause what in premature infants less than 30 weeks | inhibits surfactant production and commonly leads to resp distress syndrome |
L/S ratio of lung maturity | fetal lungs are considered mature when ratio is 2:1, two time as much lecithin (PC) as sphingomyelin, approx 35 weeks |
what is amniotic fluid tested for when looking for lung maturity | PG |
what is the shake and foam test | test of lung maturity, mixing amniotic fluid with ethanol for 15 seconds, read 15 minutes later if there is a ring of bubble, then there is enough lecithin (PC) for lung maturity. No foam do L/S ratio |
what other lung maturity tests are there | surfactant-albumin ratio (SAR), fluorescence polarization essay |
how can lung maturity be artificially induced | administration of glucocorticoids |
what are the limitations of glucocorticoids in inducing lung maturity | must be administered between 27-34 weeks, at least 48 hours prior to delivery and delivery must be within 7 days |
what other factors influence lung maturation | thyroxine thyrotropin-releasing hormone, b-adrenergic drugs, estrogen, prolactin and epidermal growth factor |
do fetus of preeclamptic woman show acceleration of lung maturation | no, once thought to be true, it is not. |
Surfactant is vital, it enhances capillary circulation allowing for what | normal V/Q ratios, protection against barotrauma (it also aids in evacuation of lung fluid) |
what is the leading cause of pulmonary complications in neonates | lack of surfactant or deterioration of its production following birth |
what happens to lungs with little or no surfactant | they become stiff and noncompliant, causing >WOB |
why is support indicated for infants with little or no surfactant | they will exhaust and die from combination of energy loss, hypoxia and hypoventilation |
what is the fluid content of the lung at term | 20-30 mL/kg, roughly equivalent of FRC |
what is the composition of fetal lung fluid | lower in ph, protein and bicarb than amniotic fluid, but higher in sodium and chloride, produced all through gestation until just befor birth |
what is the function of fetal lung fluid | maintain patency of developing airways, helps in formation, size and shape of potential airways |
how is lung fluid expelled prior to delivery | 1/3 is squeezed out when thorax descends maternal pelvis during delivery, the rest is absorbed with in hours of delivery |
hazards of lung fluid retention | (especially in cesarean section delivery) lack of thorax squeeze cause retained secretions, if not rapidly absorbed PPV can help. Failure to remove can cause transient tachypnea of the newborn (TTN) or RDS type II, |
what is the first major organ to develop? | heart |
why is pressure in the right or venous circulation higher than the left in fetal circulation | 1fetal lungs have very high resistance to blood flow and high pulm vascular resistance-high pressures in right side, also becouse placenta offers little resistance to blood flow-so low resistance on left side |
fetal blood flow to the heart | nutrients and 02 from placenta, to umbilical vein, ductus venosus (shunt liver), inferior vena cava, right atrium (mix w/venous from superior v cava), foramen ovale (shunt r to l atrium), right atrium to pulm artery, ductus arteriosus (shunts to aorta) |
fetal blood flow beyond the fetal heart | foramen ovale to left vent, aorta and combines with blood from ductus arteriosus (some blood to upper organs), aorta split into two common iliac arties, further split to internal/external illiac arteries, internal illiac become umb arteries, to placenta |
best way to remember fetal blood flow | veins travel toward the heart, arteries travel away, in fetal veins carry o2 rich blood from mom, and arteries carry o2 poor toward mom, |
baroreceptors | receptors located in the bifurcaton of the carotid arteries and aortic arch, stimulation leads to bradycardia and hypotension |
chemoreceptors | present but not active in fetus, located in carotid arteries and orta, sensitive to PaO2, PaCO2 and PH they regulate ventilation-help initiate first breath |
intrauterine structures | placenta, umbilical cord, amnion, amniotic fluid |
Placenta | |
chorionic villa | projectiles of the trophoblast that attach to the endometrium of the uterus |
inervillous spaces | small pockets surrounding chorionic villa that contain maternal blood |
cotyledons | one of 15 to 25 segments on the maternal side of the placenta, each segment contains a villa and a inervillous space |
umbilical cord | lifeline between mother and fetus, 3 vessels surrounded by a tough gelatinous material caled whartons jelly, 3 vessels-2arteries, 1 vein |
wharton's jelly | tough gelatinous material that surrounds and protects the umbilical cord, allowing it to bend but protecting it from collapsing, kinking and occluding blood flow |
amnion | sac that surrounds the growing fetus and holds the amniotic fluid, arises from trophoblast at around 7th week |
amniotic fluid | dynamic fluid that surounds fetus, serves to protect fetus from trauma, thermoregulation, and facilitation of getal movement |
what is dynamic fluid mean in relation to amniotic fluid | it is constanly being absorbed and replenished |
where is surfactant stored | in lamellar bodies, produced in type two cells |
at what stage of embryologic development does the ovum enter the uterus | morula |
the respiratory system arises from which germ layer | endoderm |
the earliest development of the lung begins when | 24 days |
dichotomy of the airways occurs during which phase of lung development | pseudoglandular (7-16 weeks) |
the following statement best describes surface tension | the tendency of liquid surface to contract |
what is the best indicator found in ambiotic fluid of lung maturity | PG |
what does not appear to accelerate fetal lung maturation | maternal preeclampsia |
the following are true statements about lung fluid | approx 20-30mL/kg present at birth, lower ph, protein and bicarb than ambiotic fluid, higher sodium and chloride than ambiotic, helps to maintain patency of developing airways |
what is one of the biggest hazards of cesarean section | TTN |
heart develops from what germ layer | endoderm |
embryologic truncus arteriosus develops into what | pulm artery and aorta |
path of blood that is shunted through forament ovale is | right to left atruim |
ductus arteriosus shunts blood where | pulm artery to the aorta |
the folling statement about baroreceptors is correct | they are actually stretch receptors |
in the placenta, the fetal vessels are cantained in the | chorionic villa |
polyhydramnios is defined as | excessive amniotic fluid |
what are the possible causes of polyhydramnios | hydrocephalus, esohageal atresia, down syndrom, cleft pallate |
assessment of the fetus during the first trimester is facilitated by what technique | transvaginal ultrasound |
can infection be detected by ultrasound | no |
what can be detected by ultrasound | position of the fetus, position of the placenta and volume of amniotic fluid |
a high level of alpha-fetoprotein found during amniocentesis indicates what | neural tube defect |
what test of amniotic fluid is used to help determine fetal kidney maturity | creatinine level |
bilirubin from amniotic fluid tests for what | liver maturity |
monitoring fetal heart rate during labor and delivery is used to detect what? | placenta insufficiency, compression of the umbilical cord and bradycardia secondary to vagal stimulation |
the most accurate method of measuring fetal heart rate is | fetal scalp electrode |
common cause of fetal bradycardia is | asphyxia |
type III decelerations are caused by | compression of the umbilical cord |
fetal scalp ph is the lower limit of what | 7.25 |
the following statements are true about fetal movements | greatest activity between 28-34 weeks, destress and stillbirth are common if fetus is inactive, move can be detected as early as 7 weeks |
what are the common measurements in a biophysical | fetal breathing, gross body movement, fetal tone, reactive NST and amniotic fluid volume (normal score 8-10) |
cordocentesis | removing fetal blood sample from the cord |
factors of maternal history that place fetus at high risk | previous miscariage, previous premature labor, asthma, maturnal obesity |