Kidney Kidney The kidneys are two bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood exits into the paired renal veins. Each kidney is attached to a ureter, a tube that carries excreted urine to the bladder. The nephron is the structural and functional unit of the kidney. Each adult kidney contains around 1 million nephrons. The nephron utilizes four processes to alter the blood plasma which flows to it: filtration, reabsorption, secretion, and excretion. The
Pulmonary artery Pulmonary artery A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The largest pulmonary artery is the "main pulmonary artery." or "pulmonary trunk" from the heart, and the smallest ones are the arterioles, which lead to the capillaries that surround the pulmonary alveoli. In order of blood flow, the pulmonary arteries start as the pulmonary trunk or main pulmonary artery. The main pulmonary artery begins at the base of the right ventricle. It is short and wide—approximately in length and in diameter. The main pulmonary