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55 Cards in this Set
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Terms Drawing, Normal adult flow and fetal heart flow due wednesday 1 hw friday, 1 hw wednesday START NRP book for friday. need to do the online courses |
Fertilization, union of sperm and ovum (egg) (zygote) in the fallopian tubes Gestational age: time since conception Normal pregnancy = 38 weeks to 42 weeks Term pregnancy is 40 weeks, or 38 to 42 weeks anything before 38 is preterm, after after 42 is post term |
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Stages of untrauterine life |
First stage is the period from conception to implantation (12 to 14 days) ovum First 3 months: embryo 4th month: delivery: Fetus :it is in this phase where general growth and fine development occur Gain about half a pound a week the last 4 weeks in uterine growth |
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Fertilizations |
Zygote: fusion of the nuclei of egg and sperm |
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Cellular division |
Fertilizaed ovum travels from fallopian tube toward uterus. Reaches uterus in 4 to 5 days Zygote divides into identical cells with further division of 4, 8, 16, et BLASTOMERES: Cells produced during cellular divison Zona Pellucide: transparent tissue that surrounds blastomere |
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Fertilizations |
MORULA: when 16 to 50 cells grow and form a ball, they mooed towards the uterus :Fluid builds around the morula and a cavity forms in the center BLASTOCYST( 5 days after conception) this contains stem cells. Further deelopment occurs only if this is implanted into the uterus (endometriums) Tropholblast: replaces zone pellucida and becomes part of the placenta |
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Implantation begins |
5 to 6 days Cells secrete an enzyme that creates the implantation site Site becomes swollen with new capillaries and circulation begins to the site Planceta: spongy structure in the uterus where fetus gets O2 and nutrients and CO2 carried away No direct contact with moms blood and babies blood |
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Impmlantation complete |
Placental circultaion begins 7 to 12 days New capillaries start placental growth Cells continue to divide into embryo, amniotic sac ETC Ideal site for implantation, upper 1/3 of uterus on the back wall towards mothers spine |
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Germ layers (21 days) |
Endoderm: lungs mouth, pharynyx, liver Mesoderm: muscles, blood bone diaphragm Ectoderm: brain, spinal cord, skin |
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Week 1 to 4 |
Heart tubes form one single tube and starts to contract: this will carry them throughout life! :Contractions begin around week 4 Face and skull start to form Neural tubes form to develop the nervous system (brain, spinal cord, skin) No blood vessels yet Primitive lungs begin to form |
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Week 5 |
arms and legs |
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Week 7 |
4 chambered heart Trachea, larynx and bronchi begin Diaphragm forms and is completely develop at 7 weeks Walsh pages 14 and 15 |
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8 weeks |
muscles develp and spontaneous movement Pulmonary arteries and aorta form Cartilage and bones begin to from Webbed fingers and toes 0.61 inches long 0.04 ounce |
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Weeks 10 |
Now called a fetus The most critical part of development is complete Volume of amniotic fluid increases 1.22 inches 0.14 ounces |
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Weeks 12 |
fetus begins to move although mom cannot feel it Heart beat can now be detected Heart pumping 24 quarts/day Swallowing and sucking developed 2.13 inches 0.49 ounces |
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16 weeks |
Meconium accumulating in bowels |
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5 months 18 to 20 weeks |
dramatic growth period Fetus has phases of sleep and waking, may have a favoring sleeping position lANUGO FORMS: fine hair VERNIX develops cheese like substance that covers fetus Brown fat develops, helps in keep fetus warm (after birth), located primarily on back shoulds Babies down shiver or sweat. |
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Week 22 |
Reccognizes maternal sounds: Voice Respiratory system developing but not able to carry on gas exchange |
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Week 24, 6 months |
Eyes respond to light Respond to outside noises Nostrils begin to open Blood vessels in lungs develop closer to air sacs Surfactant is beginning to be produced Colnial atresia, nostrils are closed
surfact begins to be developed
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26 weeks |
Lungs are capable of breathing air Brain wave patterns resemble a full term baby |
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28 weeks |
breathing and body temp controlled by brain lanugo disapears, except on back and shoulders fat begins to accumulate under skin at 30 weeks, fetal position takes place because of lack of space in uterus |
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week 34 |
may start to position into the head down position (vertex position) Skin appears light pink because vessels close to the surface |
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35 weeks |
surfactant is mature Body is round and poump due to fat storage intestines accumulate large amount of meconium This may be a problem with delayed or difficult births |
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38 to 42 weeeks |
baby is full term has 300 bones, some will fuse together as adults have 206 bones Skull if not fullly solid. fontanels separate bones for delivery process
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Sensitivity |
in early stages of developemnt the embryo is sensitive to drugs, radiation and infections leading to congenital malformations :most way before mom knows shes pregnant In later stages, the getus is less sensitive as the organs at this point only grow |
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Development following delivery |
Neonate: delivery to 1 month of age Infant: 1 month to 1 year Child: over 1 year If born prior to 38 weeks, gestation, it is termed, premature neonate |
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Fetal Lung development |
Points of fetal lung Lung is nonfunctional until near term Fetal lung activity: some respiratory movements and produces some secretions Needs to be able to function IMMEDIATELY at birth Chief cause of perinatal death from 24 week gestation until 4 weeks after birth is failure of the respiratory system at 23 weeks, a gray line if they can survive, usually 24 weeks is the minimum |
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The trachea breaks off from the esophagus |
This increases the chances of a trachealesophageal fistula |
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A few interesting points |
Canalicular phase :24 weeks: 24 million terminal air sacs, then theh increase in size and number after birth until age 7. :After this they increase in size only as an adult we have 300 million 24 to 26 weeks; formation of alveolar capillary units suffiicent for extrauterine life
Saccular phase :Surfactant is mature by week 35 :at birth aroughly 50 million alveoli present |
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Development of upper resp tract |
Choanal atresia, when the membrane does not disinegrate between the nsaal and oropharynx
Page 455 there can be complete or unilateral nasal obstruction Usually associated with other abnormalities, especially CHD Happens to 1 in 700 live births :females to males are 2 to 1 |
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Surfactant and surface tension |
Remember chapter 2 in pulonary anatomy and physiology
Surface tension :Molecules inside a liquid drop attract to each another :in air/liquid layer, molecules on the surface are drawn inward and together :The inward pull causes the droplet to retract to the smallest size
Alveoli: an air/liquid layer :The surface molecules are attracted inward, thus shrinking the alveoli to its smallest diameter
Without surfactant, alveolus is much harder to expand, and higher probablity of collapse, this decreases compliance, harder to breath, first breath is the hardest |
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La Place law |
As the radius of a bubble (alveoli) decreases, the surface tension increases Once the patient has exhaled, the alveoli are smaller, there is more surface tension so it takes more pressure to inflate the lung for\next breath |
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Surfactants roles |
Produced from alveolar type 2 cells and stored in lamellar inclusion bodies Starts to form at 24 weeks gestation LOWERS SURFACE TENSION STABILIZES THE ALVEOLI ALLOWS THE NORMAL V/Q RAIO PROTESTS ALVEOLAR TISSUE FROM BAROTRAUMA lack of surfactant is: leading cause of pulmonary complications in neonates |
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Surfactant on breathing |
Surfactant is released on inspiration and spreeeeeeeead along the alveolar surface Inspiration: surfactant things out, so surface tension builds INCREASES SURFACE TENSION CAUSES ALVEOLI TO COLLAPSE (EXPIRATION) expiration: surfactant thickens on alveolar surface, so surface tension decreases. This prevents alveolar collapse |
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Lack of surfactant |
Non compliant lungs, hypoxia, patient has loss of energy even for breathing, they are now responsible for everything, so they need lots of energy
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Make up surfactant |
Phopholipids make up the majority 90% lipids :Lecithin or PC phosphatidylcholine :sphingomyelin :PG: does not start to develop until late stages of gestation growth, around week 35
:10% proteins |
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Surfactant |
Immature surfactant 1st surfactant produced 24 weeks and lacks PG Premature infants are high risk
Mature surfactant :PG is now added at 35 weeks gestation :PG is produced as surfactant reaches maturity |
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Lung maturity |
L:S RATIO: NORMAL 2:1 LEXITHIN PC: lipid that is part of the cell membrane SPHINGOMYELIN: lipid produced by the fetus. remains fairly constant throughout gestation Indicates lung maturity 35 weeks (expected) Obtained from amniotic fluid |
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Lung Maturity |
Lamellas Body Count :Another method to determine lung maturity :Uses amniotic fluid (1 ml) :takes 15 mins to have results :A value of 32k or greater is indicative of lung maturity in 99% of cases
Lamellar body counts provide relizable estimate of fetal lung maturity, lamellar body counts can be performed easily with many hematology analyzers using platelet count channel
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Lung Maturity |
SHAKE TEST: (FOAM TEST) :this is an old test, no longer available :Mix amniotic fluid with alcohol (ethanol) :shake for 15 seconds. let side for 15 minutes If a ring of bubbles are present; enough lecithin present (+ test) If not, steroids (decadron) may be given to mother to enhance surfactant maturity (decadron) :Given @ 27 to 34 weeks gestation and at least 48 hours before delivery (no more than 7 days prior |
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Lung maturity |
Lung profile Tests for L:S ratio Tests for PG
A better indicator than L:S ratio alone |
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Fetal lung fluid |
Appears early in gestation and continues until delivery and initiation of entilation Fetal lung produces and secretes itw own fluid Term: infant: the lung is filled with 20 to 30 ml/kg of fluid FRC established |
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Function of fetal lung fluid |
Patency of developing airways Helps form size and shape of alveoli Fluid exits the fetal lung through the trachea, mouth and is either swallowed or expelled into amniotic saac
Must be completely evacuated from lungs at birth Vaginal delivery: 1/3 is removed by squeezing of thorax, 2/3 is absorbed by lunphatics
TTHN transient tachypnea of the newborm |
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Complications of removal |
Cesarean section Due to lack of squeeing around chest during uterine contract TTN (transient tachypnea of the newborn) Seen a few hours post delivery
Treatment: NICU for observation, O2 CPAP, ventilation rare |
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Heart Development |
1st major organ that finishes development, beating and fuctioning by week 4, should be a 4 chambered structure |
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Fetal Heart |
Cells originate from mesoderm 2 tubes surrounded by myocardial tissue 4th week gestation: Heart beats Looks like an adult heart at 5th week |
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Fetal circulation |
oxygenated blood going to the inferior vena cava of the newborn, once umbilicord is cut, this ends It goes up into right atrium, then blood flow has an option, either tricuspid valve to RV, or across RA via foramen ovale that goes directly to the left atrium. After birth there is a muscular flap that slams that door shut (this is shunt number 2)
If it goes into the pulmonary arteries(to the lungs or), it can go to the ductus vensus directly to the aortic arch to the umbilical veing to the unbelical cord
If it does go through
Ductus venousous at the inferior vena cava
The foramen ovalle between the RA and LA
Also the umbilical arteries which branch off the descending aorta
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What makes the right heart pressure higher |
Increased pulmonary vascular resistance (PVR) Low PaO2 in fetal blood The lungs are very collapsed in utero So... the right heart works harder causing increased pressures PVR in a newborn is lower than a baby in utero |
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Why is the left side heart pressure lower? |
Placenta offers little resistance to blood flow Placenta has a large amount of vasculature which lets the blood return with ease So... less pressure |
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Fetal Shunts |
Ductus Venosus: diverts blood from umbilical vein into inferior vena cava (no problems because once cord is cut, no blood flow)
Foramen ovale: diverts blood from right atrium to left atrium (can cause problems)
Ductus arteriosus: diverts blood from pulmonary artery to descending aorta (can cause problems) |
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Fetal circulation: blood flow |
Placenta to umbilical vein :Has the highest O2 concentration with a PaO2 = 29 torr and SpO2 = 80%
Blood leads to liver where 1/2 goes to liver and the other 1/2 bypasses the liver through the ductus venosus and goes directly into the inferior vena cava. |
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Fetal circulation : Blood fllow |
At the IVC, the blood mixes with deoxygenated blood from the lower extremities and drops the SpO2 to 67% This blood enters the right atrium :The SpO2
From right atrium, it can go to right ventrical or through the foramen ovale into the left atrium
Left atrium :if it goes to left vent and out to the ascentding aorta (to feed the upper body), to the descedning aorta to feed the lower body :Then back to the placenta via the 2 umbilical arteries
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Fetal circulation: blood flow (lets back track) |
Right ventricle (if blood does not shunt to left atrium) :To the pulmonary artery ::Here you have the 3rd shunt, ductus arteriosus
::Blood can go to the lung, but only 10% does because the fetal lung is filled with fluid and massive vasoconstriction (increased PVR) (pulmonary hypertension) due to the low PaO2 |
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Fetal circulation blood flow |
So, 90% of the blood bypasses the lung and goes through the ductus arteriosus into the descending aorta to gain access to the umbilical arteries
The blood then goes to the lower extremities and back to the placenta via the 2 umbilical arteries |
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NBRC question The average oxygen saturation in the umbilical ein is? |
80% |
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The premature infant appears dusky and ECHO reveals that the formaen ovale and the ductus arteriors is patent. which would cause this |
pulmonary hypertension |
