This action causes mucous to discharge from the nose and may run down the back of the throat in order to prevent these substances from causing infection or irritation. Runny nose may be triggered by other conditions such as allergies, a cold or the flu, infections or particular medicines.
The largest veins in the human body are the venae cavae. The superior vena cava carries blood from the arms and head to the right atrium of the heart. The inferior vena cava carries blood from the legs and abdomen to the heart.n the circulatory system, veins (from the Latin vena) are blood vessels that carry blood toward the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart.
Blood vessels which carry blood back to the heart from the rest of the body are called veins. The main vein is the vena cava, which carries deoxygenated blood to the right atrium. The pulmonary vein carries oxygenated blood from the lungs to the left atrium.The arteries are blood vessels which carry blood away from the heart. The main artery is the aorta, which carries oxygenated blood from the heart to the rest of the body.The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs.he main vein is the vena cava, which carries deoxygenated blood to the right atrium. The pulmonary vein carries oxygenated blood from the lungs to the left atrium. The arteries are blood vessels which carry blood away from the heart.