Dark bluish blood, low in oxygen, flows back to the heart after circulating through the body; returns to the heart through veins and enters the right atrium. This chamber empties blood through the tricuspid valve into the right ventricle.
The right ventricle pumps the blood under low pressure through the pulmonary valve into the pulmonary artery. From there the blood goes to the lungs where it gets fresh oxygen. After the blood is refreshed with oxygen, it’s bright red. Then it returns by the pulmonary veins to the left atrium. From there it passes through the mitral valve and enters the left ventricle.
The left ventricle pumps the red oxygenated-rich blood out through the aortic valve into the aorta. The aorta takes blood to the body’s general circulation. The blood pressure in the left ventricle is the same as the pressure measured in the arm.
This excellent brochure is distributed by the American Heart Association. Their National Center is located at 7272 Greenville Avenue, Dallas, Texas 75231-4596 or visit online. Your contributions will help support research and educational programs.
While a baby is in the womb the baby’s heart has a duct (passageway) that runs from the left side of the heart to the right side of the heart. Blood flows from the right side of the heart directly into the left side of the heart through this baby duct, picking up oxygen on the way through the umbilical cord. Of course, a baby in the womb does not use lungs to get oxygen. Oxygen is obtained, and carbon dioxide is carried away, through the umbilical cord. This baby duct starts to close within hours after birth as the baby’s lungs function and the baby’s left side of the heart takes over the job to pump the oxygenated blood throughout the body.