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
Bladder cancer blood. Blood in the urine may also be caused by other conditions, such as bladder or ureteric stones, infection, kidney disease, kidney cancers or vascular malformations, though these conditions (except kidney cancers) would typically be painful. Other possible symptoms include pain during urination (dysuria), frequent urination, or feeling the need to urinate without being able to do so. These signs and symptoms are not specific to bladder cancer, and may also be caused by non-cancerous conditions, including prostate infections, overactive bladder or cystitis. Patients with advanced disease refer pelvic or bony pain, lower-extremity swelling, or flank pain. Rarely, a palpable