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Lab 7: Vertebrate Anatomy: Difference between revisions
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→Circulatory System Adaptations for Oxygenation in the Fetus
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While a fetus is in utero the exchange of oxygen, nutrients,and waste products occurs across the placenta. Since the digestive tract, lungs and kidneys of the fetus will not begin to function until after birth the fetal circulation has been modified to adjust blood flow to these organs. Oxygenated blood is brought to the fetal heart through the umbilical cord, umbilical veins, and vena cava. <BR><BR> | While a fetus is in utero the exchange of oxygen, nutrients,and waste products occurs across the placenta. Since the digestive tract, lungs and kidneys of the fetus will not begin to function until after birth the fetal circulation has been modified to adjust blood flow to these organs. Oxygenated blood is brought to the fetal heart through the umbilical cord, umbilical veins, and vena cava. <BR><BR> | ||
Follow the umbilical vein, transected earlier in the dissection, as it seems to disappear in the liver. In Figure 7.5 there is a portion of the vein labeled <u> ductus venosus</U>, that is shunting about ½ the oxygenated blood directly to the vena cava and thus to the fetal heart. This is one of three modifications to the fetal circulatory system. After birth the umbilical vein and umbilical arteries atrophy and the ductus venosus gradually fills with connective tissue and closes (ligamentum venosum). <BR><BR> | Follow the umbilical vein, transected earlier in the dissection, as it seems to disappear in the liver. In Figure 7.5 there is a portion of the vein labeled <u> ductus venosus</U>, that is shunting about ½ the oxygenated blood directly to the vena cava and thus to the fetal heart. This is one of '''three modifications''' to the fetal circulatory system. After birth the umbilical vein and umbilical arteries atrophy and the ductus venosus gradually fills with connective tissue and closes (ligamentum venosum). <BR><BR> | ||
Since the lungs are not functioning in the fetus, | Since the lungs are not functioning in the fetus, two modifications to the circulation are found within the heart: The <u>ductus arteriosus</u> and the <u>foramen ovale</u>. We will look at these two modifications more closely when dissecting the calf heart. | ||
=='''Comparative Adult Anatomy of Systems in Vertebrates'''== | =='''Comparative Adult Anatomy of Systems in Vertebrates'''== | ||
