The four nitrogenous bases are A, T, C, and G. They stand for adenine, thymine, cytosine, and guanine. The four different bases pair together in a way known as complementary pairing. Adenine always pairs with thymine, and cytosine always pairs with guanine.
Human heart is comprised of four regions, components, zones or muscular containers. As, the blood quality is regulated by the blood, by keeping the deoxygenated form of blood apart from the oxygenated form of blood inside the heart and then provide suffiecient amount of materials, solutes, and other nutrients to the different tissues and organs of the human body in a proper manner.
The deoxygenated form of blood is collected and brought to the right atrium by <u>the superior and inferior venacava</u>, as it provides a more safer route for the transportation of these materials in order to remove the unwanted substance from it by sending it back to the lungs through the pulmonary artery.
Inside the lungs the blood is cleaned up and then sent back to the heart in order to be pumped into the different portions of the heart.
