Answer and Explanation:
During the body's metabolism, molecules are generated that are residues of chemical and methanbological reactions. These molecules need to be removed from the body and this process is done by the excretory system. Most of these molecules are wastewater and nitrogen compounds.
The kidneys are a very important point in this system, along with the urinary system. When blood, rich in oxygen, comes in contact with the kidneys, they are filtered by this organ. This is done through structures called the nephron which are the excretory unit of the kidneys. Within each nephron there is a collecting capsule where water and residual particles that are in the blood are captured, while the rest of the particles pass along with the blood and continue on their way to other regions of the body.
From inside the kidneys there is also a tube called the ureters, which captures the water and molecules captured by the nephron (which forms the urine) and takes them to the bladder, which directs the urine out of the body through the urethra.