Term
| when does the cardiovascular sys begin to develop in the fetus? |
|
Definition
| at the end of the third week |
|
|
Term
| when does the heart start to beat in the fetus? |
|
Definition
| at the beggining of the fourth week |
|
|
Term
| what is the critical period in cardiac development for the fetus? |
|
Definition
| 20-50 days after fertilization |
|
|
Term
| what vessel deleivers oxygenated blood to the fetus |
|
Definition
|
|
Term
| The umbilical vein enters the portal venous sys where it empties most of the blood into the _________ which connects to the __________ |
|
Definition
| most of the blood into the ductus venosus which connects to the inferior vena cava |
|
|
Term
| what is the O2s% in umbilical vein? in fetal circulation? |
|
Definition
| 80% in umbilical vein and 67% in fetal circulation |
|
|
Term
| the majority of blood entering the right atrium goes into the ____________ |
|
Definition
| foramen ovale and into the left atrium |
|
|
Term
| connects the main pulmonary artery to aorta bypassing the lungs |
|
Definition
|
|
Term
| what is the O2s% of blood in the vena cava of the fetus? |
|
Definition
|
|
Term
| blood that actually enters the right ventrical usually comes from: |
|
Definition
|
|
Term
| what happens to blood that exits the right ventricle in the fetus? |
|
Definition
| enters into the pulmonary artery and exits the pulmonary artery via the ductus arteriosus which connects to the aorta |
|
|
Term
| The ductus arteriosus should close functionally within ______ and structurally within________ after birth |
|
Definition
| functionally closes within 15hrs and structurally clloses within a few weeks |
|
|
Term
| describe the umbilical arteries: |
|
Definition
| two vessels that allow unoxygenated blood to flow from the descending aorta back to the placenta. |
|
|
Term
| what affects does the baby's first breath have on blood flow? |
|
Definition
| increase in pulmonary blood flow |
|
|
Term
| how does the removal of the placenta affect baby's blood flow? |
|
Definition
| removal of placenta removes source of prostaglandins keeping the foramen ovale, ductus venosus and ductus arteriosus open, so they will close |
|
|
Term
| why does the pressure in the left heart increase after baby's first breath? |
|
Definition
| blood from the perfused lungs is filling the left atrium |
|
|
Term
| what affect does the increased left atrium pressure have on the foramen ovale? |
|
Definition
|
|
Term
|
Definition
| flap on the left side of the atrial septum helps to form the foramen ovale |
|
|
Term
|
Definition
| rigid portion of the atrial septum on the right side that the septum primum closes against |
|
|
Term
| why would these ducts remain open longer in premature infants? |
|
Definition
| decreased lung maturity = decreased O2 levels |
|
|
Term
| what substance is released by the lungs upon initial inflation that causes closure of the ductus arteriosus? |
|
Definition
|
|
Term
| what is bradykinins mechanism of action: |
|
Definition
| potents contranctile effects on smooth muscle |
|
|
Term
| at what PO2 levels does the walls of the ductus arteriosus start to constrict? |
|
Definition
|
|
Term
| how does O2 affect prostaglandin levels? |
|
Definition
| decreases PG E2 & prostacycline |
|
|
Term
| how might PG E2 work in the Tx of coarctation of the aorta? |
|
Definition
| infusion of PGE2 might open up the coarctation to restore proper blood flow |
|
|
Term
| why does the vascular pressur in the lungs fall and how does this affect the flow through the ductus arteriosus? |
|
Definition
| increase in O2 causes vasodilation in the lungs and pressures fall which decreases the force of blood through the ductus arteriosus |
|
|
Term
| why is the umbilical cord not tied for 30-60 seconds after birth? |
|
Definition
| to xfer fetal blood from the placenta to the infant |
|
|
Term
| what significantly contributes to the increase in systemic vascular resistance after birth? |
|
Definition
| closing of the umbilical arteries |
|
|
Term
| compare right and left ventricles in fetus/infants: |
|
Definition
| right ventricle wall is thicker in the fetus/infant until after about the first month; right ventricle atrophys due to its lighter workload |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| medial umbilical ligaments/superior vesicular artery = |
|
Definition
| umbilical arteries & abdominal ligaments |
|
|
Term
|
Definition
|
|
