Excretion -The Formation of Urin - Essay Example

            The normal breakdown of tissue and the leftover products from food and liquid intake deliver wastes to the blood. Nephrons are millions of tiny cells found in the kidneys which work to filter the blood. Housed inside each nephron is a glomerulus through which blood passes. The glomerulus works to filter out extra fluid and wastes while keeping the necessary proteins and cells in the bloodstream. This process takes place in the renal corpuscle and from here the filtered material goes to the Bowman’s capsule becoming part of the glomerular filtrates composed mainly of urea, water, salts, and glucose. Most of the substances, like glucose and other nutrients, passing through the renal tubules (made up of the proximal tubule, loop of Henle, and distal tubule) are returned to the bloodstream via the peritubular capillaries by a process called reabsorption. This process begins in the proximal tubule where substances like Na+ and glucose are actively transported out of the tubules and into the capillaries. The waste products move through the loop of Henle and are secreted to the distal tubule, which then moves the materials to the collecting duct. From here the collection of wastes, in the form of urine, enters the bladder from the ureter. Finally, urine is excreted from the bladder via the urethra.