Seventy percent of our body mass is water. Without keeping the right amount of water we would die. The kidney is the key means of this control (see later). 6. Temperature. The enzymes that control every chemical reaction in our body work best at their optimum temperature of 37 degrees Centigrade. If our body cells get too hot or too cold they would die.
Hywel Vaughan. answered on 25 Jun 2010: Hi wildrosa, The biggest vein in the body is the âinferior vena cavaâ â this is the vein that returns the blood from the bottom of your body to your heart. The blood is de-oxygenated, and enters the right atrium of your heart â this is at the lower right, back side of your heart.
The top of the heart connects to a few large blood vessels. The largest of these is the aorta, or main artery, which carries nutrient-rich blood away from the heart. Another important vessel is the pulmonary artery which connects the heart with the lungs as part of the pulmonary circulation system. The two largest veins that carry blood into the heart are the superior vena cava and the inferior vena cava. They are called vena cava because they are the heart's veins..