The urinary tract system is a group of organs of the body, which are responsible for the excretion of urine. In humans, the urinary system includes 2 kidneys, a pair of tube-like structures, called the ureters, which connect the kidneys to the bladder. The bladder is connected to the urethra, which delivers the urine to the outside of the body. The primary function of the urinary tract system is to remove substances from the blood, to form urine and help to regulate various metabolic processes.
The kidney is responsible for two primary functions. First, the kidneys work by extracting water, urea, mineral salts, toxins, and other waste products from the blood with filtering units called nephrons. Secondly, the kidneys regulate the production of red blood cells, blood pressure, blood volume, blood composition and pH of the blood. The functional unit of the kidney is called the nephron. From the nephrons, the collected urine passes through thick-walled tubes called ureters.
The kidney is one of a pair of small bean-shaped organs of the urinary system, located near the spine. They lie on either side of the spinal column in a depression high on the posterior wall of the abdominal cavity, and are positioned behind the parietal peritoneum, called the retroperitoneum, against the deep muscles of the back. The nephron consists of a renal corpuscle made up of a glomerulus and Bowman's capsule, and a renal tubule made up of a proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct. The kidney contains a hollow chamber, called the renal sinus. Through the renal sinus passes various blood vessels, nerves, lymphatic vessels and the ureter. The superior end of the ureter is expanded to form a funnel-shaped sac called the renal pelvis, which is located inside the renal sinus. The renal pelvis is subdivided into several tubules, or major calyces. The major calyces are then subdivided into minor calyces.