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.
superior vena cava, the second largest vein of the body, returning deoxygenated blood from the upper half of the body to the right atrium. It is about 2 cm in diameter and 7 cm long.