izločala

• The liver plays a tremendous role in directing dead cells and leftover chemicals to the digestive and urinary systems
• The liver can't actually escort waste out of your person
• The lungs can lend a hand, exhaling carbon dioxide, and the colon will eventually poop out unusable stuff and old cell-parts
• Much of your chemical waste still needs to be sorted and disposed of, so the urinary system steps in to bat clean-up
• Urinary system


  Regulates water volume, ion salt concentrations, pH levels, and influences red blood cell production and blood pressure
• Urinary system's main purpose

  Filters toxic leftovers from your blood and ferries it out of the body
• Most of what's in your blood is totally removed by the kidneys, then your body pulls back what it wants to hold onto, before the rest is sent to the bladder
• Metabolizing nutrients, especially protein


  Produces ammonia, which is toxic
• Liver


  Converts ammonia into less-toxic urea, which the kidneys filter out into pee
• Dirty, pee-soaked toilets and cat litter boxes smell like ammonia because urea can degrade back into ammonia
• Kidneys


  • Pair of dark red, fist-sized, bean-shaped organs that sit on each side of the spine against the posterior body wall
  • Retroperitoneal, lying between the dorsal wall and the peritoneum
• Layers of the kidney


  • Cortex
  • Medulla
  • Renal pelvis
• Kidneys filter about 120 to 140 liters of blood every day
• Nephrons


  Microscopic filtering units in the kidneys, where the real business of blood-processing and pee-making begins
• Nephron function


  1. Filtration

  2. Reabsorption

  3. Secretion
• Glomerulus


  • Tangle of capillaries in the glomerular capsule that allow fluid, waste products, ions, glucose, and amino acids to pass from the blood into the capsule, but block out bigger molecules like blood cells and proteins
• Filtrate


  The stuff that gets squeezed out of the blood into the glomerulus
• Parts of the renal tubule


  • Proximal convoluted tubule (PCT)
  • Nephron loop/Loop of Henle
  • Distal convoluted tubule (DCT)
• Proximal convoluted tubule (PCT)


  Reabsorbs valuable commodities like ions, glucose, and water back into the blood
• Loop of Henle


  Creates a salt concentration gradient in the medulla to drive the reabsorption of water
• Urea


  Used by the kidneys to ramp up the concentration gradient in the medulla, making it more effective at drawing out water from the collecting duct
• Urea recycling


  Urea escapes the urine, finds its way back into the loop of Henle, and runs the whole course again back to the collecting duct
• Tubular secretion


  Selectively transports extra waste like hydrogen, potassium, and certain organic acids and bases out of the blood and into the urine
• The kidneys filter metabolic waste and balance salt and water concentrations in the blood