(PhysOrg.com) -- Water vapor and clouds are the major contributors to Earth's greenhouse effect, but a new atmosphere-ocean climate modeling study shows that the planet's temperature ultimately depends on the atmospheric level of carbon dioxide.
Deoxygenated blood enters the right atrium through three major veins: the superior and inferior vena cava and the coronary sinus. The superior vena cava returns all of the blood to the heart from tissues superior to the heart in the head, neck, arms and upper thorax.Likewise, the inferior vena cava returns blood to the heart from tissues inferior to the heart, including the legs, abdomen and lower thorax.he right atrium is one of the two atria of the heart, which function as receiving chambers for blood entering the heart. It is located to the right of the left atrium and superior to the much larger and more muscular right ventricle.
The Inferior vena cava-just like the Superior vena cava -, returns blood to the heart. When blood is returning to the heart, that blood is already circulated in the body, therefore it is already downloaded the oxygen to the body tissues, and picked up the carbon dioxide from them.he Inferior vena cava-just like the Superior vena cava -, returns blood to the heart. When blood is returning to the heart, that blood is already circulated in the body, therefore it is already downloaded the oxygen to the body tissues, and picked up the carbon dioxide from them.