Excretion

• Each capillary cluster in the kidney is associated with the cup shaped end of a coiled tube called Bowman's capsule, which collects the filtrate

  
  
• Each kidney has numerous filtration units called nephrons packed closely together.Each nephron has a Bowman's capsule containing a bunch of capillaries called glomerulus.Blood gets filtered in the glomerulus.
• Substances like glucose, amino acids, salts, and a major amount of water are selectively re-absorbed from the initial filtrate as urine flows along the tube
• The amount of water re-absorbed depends on the excess water in the body and the amount of dissolved waste to be excreted
• Urine from each kidney enters the ureter, a long tube that connects the kidneys with the urinary bladder
• Urine is stored in the urinary bladder until the pressure of the expanded bladder leads to the urge to pass it out through the urethra
• The bladder is muscular and under nervous control, allowing us to usually control the urge to urinate