the excretory system

• Each kidney is about the size of your fist.
• the excretory system includes 7 organs : the skin, lungs, liver, kidneys, ureters, urinary bladder, and urethra
• The kidneys are bean-shaped structures located on either side of the spine at the level of the middle back
• the skin eliminates wastes by releasing sweat.
• the lungs eliminate wastes, such as carbon dioxide, by exhaling.
• the liver converts nitrogen wastes into less toxic urea.
• urea is transported to the kidneys.
• kidney filters blood and removes waste products from it.
• ureters transport urine from the kidneys to the urinary bladder where it is stored until it is released through the urethra.
• the excretion is the process by which metabolic wastes are eliminated to maintain homeostasis.
• each kidney contains nearly a million individual processing units called nephrons.
• nephrons are where impurities are filtered out, wastes are collected, and purified blood is returned to the circulation.
• blood purification in the kidneys involves two processes : filtration and reabsorption.
• passing a liquid or gas through a filter to remove wastes is called filtration.
• the filtration of blood mainly takes place in the glomerulus.
• find the glomerulus and bowman's capsule

  A) glomerulus

  B) bowman's capsule

  
• much of the fluid from the glomerulus capillaries flows into Bowman’s capsule.
• the process by which water and dissolved substances are taken back into the blood is called reabsorption.
• Kidneys filter your 5 Liter blood volume 400 times/day
• Most of this fluid is returned to your blood, you only excrete ~1.5 Liters of urine/day
• A number of materials, including salts, vitamins, amino acids, fats, and glucose, are removed from the filtrate by active transport and reabsorbed by the capillaries.
• The presence of protein or glucose in urine can be indicators of diseases
• Drugs generally remain in the filtrate and are eliminated in urine.
• Substances such as calcium, magnesium, or uric acid salts in the urine can crystallize and form kidney stones.