Urine (wee wee), how it is produced. The basics.
How Urine is produced. The basics.
The Urinary system basically consists of 2 kidneys, each having 1 Uterer joining it to the Bladder, from the bladder is 1 discharge tube, called the Urethra.
Each kidney is composed of around 1 million units called Nephrons, it is these that actually collect the urine from our blood.
The main process in the production of urine is that of Simple Filtration, this takes place between the semi permeable walls of the glomerulus and the glomerular capsule. From the blood, water and other small enough molecules can pass through from the glomerulus into the glomerular capsule (though some may be reabsorbed later whilst passing through the loop of Henie). Blood cells, plasma proteins and other large molecules are too big to filter through.
This filtration is assisted by differences in pressures; note the diameter of the efferent arteriole is less than that of the afferent arteriole, thus creating a build up in pressure (see figures in diagrams).
Substances that can filter through are water, mineral salts, amino acids, ketoacids, glucose, hormones, creatinine, urea, uric acid, toxins and certain drugs. This mixture becomes urine, liquid waste.
Substances that cannot filter through are leukocytes, erythrocytes, platelets, plasma proteins and some drugs.
The produced urine then leaves the kidney through the collecting ducts and into the uterers and on to the bladder for storage until one needs to urinate.