HGH (Human Growth Hormone) is a protein hormone which is produced by the endocrine system in the human body. It is made from 190 individual amino acid molecules, and is secreted by the pituitary gland.
However, in pulmonary circulation, the arteries carry deoxygenated blood from the heart to the lungs, and veins return blood from the lungs to the heart. The difference between veins and arteries is their direction of flow (out of the heart by arteries, returning to the heart for veins), not their oxygen content.he pulmonary veins carry relatively oxygenated blood from the lungs to the heart. The superior and inferior venae cavae carry relatively deoxygenated blood from the upper and lower systemic circulations, respectively. The portal venous system is a series of veins or venules that directly connect two capillary beds.
  Veins take blood to the heart, arteries take blood away from the heart. The vessels that carry blood to the heart are called veins. Those that supply the body with blood â¦ from the heart are called arteries.Examples are the jugular veins that return blood from the head, and the carotid arteries that supply blood to the head.+ 1 other found this useful.he answer to the question is veins, they are the vessel that carries blood back to the heart. The arteries to the opposite, the carry blood away from the heart and to the res â¦ t of the body.