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bruscki
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∙ 11y ago
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When does a baby have a heart?
A fetus's heart develops early (3-5 weeks after conception). It starts out as a tube and then grows into 4 chambers around 5 weeks. It starts beating around 5 weeks but usually can't be heard until 7-9 weeks. During weeks 20-24 a fetus's heart heart develops more fully. An ultrasound of the heart during this time can rule out some congenital heart defects (CHDs) just by looking at the shapes of the four chambers of the heart. (Some CHDs are not detectable by ultrasound.) Before birth, the fetus's heart pumps blood oxygenated in Mom's lungs received via the placenta. During this time, an extra pathway (PDA) exiting the baby's heart is left open. After birth, this extra pathway closes and the heart pumps blood to the baby's lungs to get oxygen in the bloodstream.
What is the incidence of atrial septal defect?
Atrial septal defects (ASDs for short) are caused by a defect in the development of the wall between the two upper chambers (the atria) of the heart. During the development of the fetus, the heart begins as a single hollow tube that must fold, twist, and otherwise contort itself into the four-chambered heart seen at birth. In early fetal life, the first attempt at this produces a heart with two chambers: an upper atrium and a lower ventricle. These two chambers are then partitioned by adding a wall in the middle of each; thus two chambers become four chambers. The wall that separates the two atria is called the atrial septum, while the wall that separates the two ventricles is called the ventricular septum. In normal development, the atrial septum begins with a few holes in it. These holes are important for the normal circulatory system of the fetus. During development, however, tissue must grow over these holes in order to sustain life outside of the mother's womb. If the two holes are not completely covered over, then there is a defect in the wall separating the atria -- an atrial septal defect. The precise causes for atrial septal defects are not known, although they have probably often have to do with defective communication between cells that form the septum. Some septal defects tend to run in families and have known associations with genetic irregularities such as Down syndrome.
Chart of the DOW Industrial Average from January 2005 to November2008?
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