Human body
Blood vessels carry blood throughout the body, which moves because of the beating of the heart. Venules and veins collect blood low in oxygen from tissues throughout the body. These collect in progressively larger veins until they reach the body's two largest veins, the superior and inferior vena cava, which drain blood into the right side of the heart. From here, the blood is pumped into the lungs where it receives oxygen and drains back into the left side of the heart. From here, it is pumped into the body's largest artery, the aorta, and then progressively smaller arteries and arterioles until it reaches tissue. Here blood passes from small arteries into capillaries, then small veins and the process begins again. Blood carries oxygen, waste products, and hormones from one place in the body to another. Blood is filtered at the kidneys and liver.
Thyroid ima artery
The artery is only present in approximately 3–10% of the population. Thyroid ima artery is of surgical importance; due to its relatively small size and infrequent presence it can cause complications such as severe bleeding in surgery of the thorax, trachea, thyroid or parathyroid glands. Knowledge of occurrence of the artery is especially important during tracheostomy and thyroidectomy. Because the artery is smaller than the other thyroid vessels, and having an origin from one of the bigger vessels, a brisk cut while performing the surgery may cause complications such as severe hemorrhage and significant blood loss. The artery, if dissected, may draw back into the mediastinum and further complicate the condition by causing hemorrhage and clots in the thoracic cavity.