|
 In a normally functioning heart, each of the four valves has its own set of “gates” or tissue flaps that swing open to let blood flow from one area to the next. Between contractions, the flaps should neatly close again until the next cycle begins. Thus, blood should flow only in one direction and only at the right time. The routes traveled by oxygen-rich and oxygen-poor blood are:
- Oxygen-rich blood returns to the left side of the heart from the lungs, via the pulmonary veins, and travels to the left atrium. From the left atrium, it passes through the mitral valve and into the left ventricle. From the left ventricle, it is pumped through the aortic valve (sometimes referred to as the “gatekeeper” of the heart) and into the aorta to nourish the rest of the body.
- Oxygen-poor blood returns to the right side of the heart from the rest of the body via the veins, and enters the right atrium. From the right atrium, it passes through the tricuspid valve into the right ventricle. From the right ventricle, it is pumped through the pulmonic valve and into the pulmonary artery, which carries the blood to the lungs for more oxygen.
| 
/doctor_89.jpg "ulcerative colitis tips")
