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104 Cards in this Set
- Front
- Back
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What is the O2 saturation of blood in the umbilical vein?
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80%
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How is circulation different in the fetus compared to adult?
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-Blood is shunted around liver
-Blood shunts from R/L in heart |
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fetal structures within the heart allow blood to bypas what during gestation
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lungs
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what do umbilical arteries become after birth?
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median umbilical ligaments
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What are the blood volume and blood viscosity changes that occur during pregnancy?
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Total blood volume up 40%
plasma volume up 50% RBC volume up 30% Hematocrit down 2-3% (physiological anemia) |
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What are the 3 important shunts in fetal circulation?
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1. Foramen ovale
2. Ductus arteriosus 3. Ductus venosus |
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What vessel carries O2Rich blood to the fetus?
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Umbilical vein
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What does the foramen ovale do
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shunts blood from the right to left atrium bypassing nonfunctioning fetal lungs
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what does the umbilical cord consist of?
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one vein and 2 arteries
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What are the heart/function changes seen during pregnancy?
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Increased resting CO (up 30-70%)
Increased SV (due to increased vascular volume) increased HR Frank-starling improvement in performance due to increased ventricular volumes |
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Where does most of the blood that passes through foramen ovale come from?
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IVC
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What shunts blood around the liver? What does it carry it to?
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Ductus venosus - to IVC
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what does the ductus arteriosus do
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shunts blood from the pulmonary trunk to the aortic arch bypassing the lungs
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what does the umbilical vein connect? What kind of blood does it contain?
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Connects the placenta to the fetus where it connects with the left portal vein within the liver. It contains o2gyenatied blood
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What kind of cardiac remodeling takes place during pregnancy?
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there is a major increase in Left Ventricle Mass (up to 30% later in pregnancy)
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Why does blood pass thru foramen ovale?
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To bypass the lung circulation, it's not working at that time anyway.
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What shunts the blood from R/L atrium?
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Foramen ovale
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what does the 2 large umbilical arteries do
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transport deoxygenated blood from the fetus to the placenta for reoxygenation and metabolic waste removal
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Describe the course of the umbilical vein>
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-courses from the midline posteriorly and cephalad along the free margin of the falciform ligament.
-Joins the LPV -courses superior and to the right forming the transvers part of the pt portal vein. -this joins the rt portal vein. |
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How does resistance and BP change during pregnancy?
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Systemic Vascular resistance decreases by up to 50% (due to a low resistance placental circulation, and estrogen levels)
BP- MAP drops till mid pregnancy, then returns to normal. (decreased MAP due to decreased TPR) |
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What happens to the blood from IVC that passes thru foramen ovale?
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It is pumped out the aorta and goes to the head.
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What blood goes through Foramen ovale?
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That from IVC
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what does the umbilical vein do
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transports oxygenated, nutrient rich blood from the placenta to the fetus
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What is the course, and content of umbilical arteries
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they contain deoxygenated blood, and at the cord insertion site, they run inferiorly along the margin of the urinary bladder and return deoxygenated blood to the placenta
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Where does gas exchange occur for the fetus?
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in the placenta
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Where does most blood that passes thru Ductus arteriosus come from?
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SVC
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Where does blood from SVC go?
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Through the Ductus Arteriosus
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a small vessel that transports a small volume of blood from the umbilical vein to the inferior vena cava
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ductus venosus
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What does the ductus venosus do?
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shunts blood into the left or middle hepatic vein and then into the IVC
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how do the left and right sides of the heart work to pump in a fetus?
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these work in parallel
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Why does blood from the SVC go thru the ductus arteriosus?
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Because after going in the right atrium and right ventricle, then it gets pumped into the pulmonary trunk; but it doesn't need to go to the lungs, so it goes from the pulmonary trunk right into the aorta.
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What does the Ductus arteriosus connect?
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The pulmonary trunk and Aorta
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most blood entering the umbilical vein passes thru what
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the fetal liver
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What is the foramen ovale?
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an opening that allows blood to be shunted from the right atrium to the lt atrium.
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What carries oxygenated blood from the placenta to the fetus?
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the umbilical vein
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Where does the blood that passes from the ductus arteriosus into the aorta go?
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To the lower body
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What takes deoxygenated blood back to the placenta?
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Umbilical arteries
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There is high pulmonary vascular resistance due to
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hypoxia and alveoli that are mostly collapsed
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What vessels does the foramen ovale hold to gether?
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The plmonary artery and the aorta
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what carries wastes from fetus to the placenta?
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umbilical arteries
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Why does IVC blood go to the head and SVC blood goes to the lower body?
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Not really sure.
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What does the Ductus venosus become at birth?
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Ligamentum venosum
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there is low systemic vascular resistance due to what
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blood flow through the placenta
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When(after birth) is the foramen ovale closed?
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about the 10th day
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What organs does the placenta perform the functions of?
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Lungs
GI Liver Kidneys |
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What happens to fetal circulation at birth when the baby takes a breath?
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1. Pulmonary vascular resistance becomes much less
2. Now blood pumps into the pulmonary circulation, so left atrial pressure rises a lot and shuts foramen ovale |
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What does foramen ovale become?
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Fossa ovalis
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oxygenated blood flows form the placenta to where
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through the liver into the inferior vena cava
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What happens to the ductus arteriosus after birth?
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it is completely closed from the 4th to the 10th day after birth. It degenerates into the ligamentum arteriosum which connects the left pulmonary artery to the artch of the aorta
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What does the ductus venosus do?
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this shunts blood from the Umbilical vein into the IVC.
allows blood from placenta to bypass the liver (50% of blood) |
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What does the increase in oxygen in pulmonary and cardiovascular cirulation do?
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Decreases the concentration of circulating prostaglandins, failing to keep open the ductus arteriosus - so it shuts.
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What does the Ductus Arteriosus become?
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Ligamentum arteriosum
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How much of the deoxygenated blood returning to the right atrium goes to the right ventricle
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75-85%
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what does the umbilical vein become?
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the ligaentum teres
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what does the foramen ovale do?
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this is a RIGHT to LEFT shunt in the atria of the fetal heart.
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What molecule will keep the ductus arteriosus OPEN?
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Prostaglandin
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What major changes occur in fetal circulation at birth?
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-Shunts close
-Pulmonar circulation starts -Pressure on Left > Right -Umbilical vessels obliterate |
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What is the fossa ovalis
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an indentation in the inter-atrial septum and is a remnant of the foramen ovale
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what does the ductus venosus become?
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ligamentum venosum
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what does the ductus arteriosus do?
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this is a RIGHT to LEFT shunt,.
takes blood from the pulmonary artery and shunts it to the aorta |
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What molecule will SHUT the ductus arteriosus?
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Indomethacin
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pathologic patent foramen ovale (PFO)
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the foramen ovale remains open after birth
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what are 3 fetal structures that do not function until after birth
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lungs
kidney gastrointestinal |
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What is obliterated umbilical
-Vein -Artery |
Vein = ligamentum Teres
Artery = Medial umbilical ligaments |
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What is the resistance in the fetal lung like?
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it is high resistance
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What is the ligamentum arteriosum
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a tissue connection between the aortic arch and the pulmonary trunk and is the remnant of the ductus arteriosus
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what does the fetus eliminate into maternal circulation
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carbon dioxide
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what is the resistance like in the placentas vascular bed?
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this is low
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pathologic patent ductus arterisus (PDA)
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the ductus arteriosus remains open after birth
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what kind of structure is the placenta?
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intrauterine structure
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what is the CCO?
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this is combined cardiac output, it is the sum of the left and right sides of the fetal heart pumping together
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What is the placenta attached to the fetal umbilicus by?
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umbilical cord
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How much of the CCO does the ductus venous shunt? from where to where?
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this shunts 50% of CCO from the the umbilical vein into the IVC
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What is the fetal blood O2 sat when it enters the placenta?
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60% O2 sat
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Does direct mixing of maternal and fetal blood occur within the placenta?
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no, but there is diffusion across the intervillous spaces
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what is the fetal blood O2 sat when it returns to the IVC from the placenta (via ductus venous)
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85% O2 sat
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Where is the most oxgenated blood in the fetus?
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from the placenta to where it bifercates into the ductus venosus, and LT portal vein.
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What is the major change that leads to the establishment of pulmonary circulation?
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during birth, the first breath expands the lungs and cases a Decrease in Pulmonary Resistance
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Which lobe of the liver is larger in a fetus?
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the lt is larger than the right
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What cardiovascular changes does removal of the placenta trigger?
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a large increase in total peripheral resistance
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What is the most highly oxygenated area of a fetus
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The left lobe
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What are the first changes that occur when the first breath is taken?
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Relaxing of pulmonary precapillary vessels by O2
Decrease in pulmonary pressure and resistance Increased blood flow in pulmonary circuit |
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Should you put color on when looking at the fetus?
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no
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What happens to circulation when the foramen ovale closes?
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Increase in LA pressure
LA pressure exceeds RA pressure Foramen Ovale is closed |
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What is the relationship between the diameter of umbilical arteris and veins?
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the combination of the diameter of the arteries is the diameter of the vien
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What does cutting the umbilical cord do to fetal cardiovascular system?
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this decreases venous return to RA
reduces atrial pressure ductus venosus closes, resistance in system increases venous return decreases, decreasing RA/LA pressure |
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where do the vessels diverge?
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at the level of the umbilicus
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What happens when the pulmonary pressure falls below the aortic pressure?
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the flow through the ducuts arteriosus is reversed, now a left to right shunt
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where do umbilical veins travel?
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cephalic and oblique
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what cause an atrial septal defect? what happens?
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this is caused by a failure of the foramen ovale to close.
produces a LA to RA shunt, dilated RA/RV, and pulmonary hypertension |
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where do umbilical arteries travel?
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toward the legs between the rt and lt atrium via the foramen ovale.
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what does a ventricular septal defect cause?
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this is a LV to RV shunt, provides more blood to lungs
pulmonary hypertension increased blood return to LA, leads to left heart remodeling |
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How often does the foraem ovale open and close?
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2 times per cycle
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what does a patent ductus arteriosus do?
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this causes a L-R shunt, flowing from the aorta to the pulmonary artery
LV and LA are overloaded due to increased blood volume |
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where does most blood go in a fetus?
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goes from the rt atrium to the lt atrium and to the lt ventricle, then through the aorta.
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Where does most o2 profuse?
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the head
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where does less of the blood in a fetus go?
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to the rt ventricle and to the pulmnary artery.
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where is the most oxgenated blood found?
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in the liver, heart, and brain
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what is the eustachian tube?
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the IVC enters the Rt atrium through the eustachian valve
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Where does the cord insert?
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the middle of the placenta
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what does the ductus venosus form after birth?
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the ligamentum venosum
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what does the foramen ovale become after birth?
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the fossa ovalis
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what does the umbilical vein become after birth?
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ligamentum teres
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what do the umbilical arteries become after birth?
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medial umilical ligaments
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