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
Urinary bladder a series of ridges, thick mucosal folds known as rugae that allow for the expansion of the bladder. The Latin phrase for "urinary bladder" is "vesica urinaria", and the term "vesical" or prefix "vesico -" appear in connection with associated structures such as vesical veins. The modern Latin word for "bladder" - "cystis" - appears in associated terms such as cystitis (inflammation of the bladder). The outside of the bladder is protected by a serous membrane. The bladder wall itself is smooth muscle. The inner side of the bladder is lined with a mucosal membrane consisting of a surface glycocalyx