MEDICAL ANIMATION TRANSCRIPT: The kidneys are located on either side of the spinal column in the posterior abdominal wall. Adrenal glands sit on top of the kidney. The medullary pyramid and outer cortex compose the renal lobe. Branches of the renal artery supply each renal lobe. The smallest branches of the renal artery called afferent arterioles, supply the excretory components of the kidney called nephrons. Each nephron consists of a renal corpuscle and a renal tubule. The first step of urine production, called glomerular filtration, occurs in the renal corpuscle. It consists of a network of capillaries called the glomerulus and Bowman's capsule. The diameter of the afferent arteriole is larger than the efferent arteriole. This size difference produces high pressure within the glomerulus. The pressure forces the smallest substances such as water, nitrogenous waste, amino acids, glucose, sodium ions, and calcium ions out of the blood into Bowman's capsule through tiny spaces in the ...