Excretion

• Gouty arthritis

  Gout defect in metabolism uric acid deposited in joint which causes pain and joint problems Increased uric acid level in blood
• Excretory structures in animals

  . Invertebrates - simple tubular forms

  . Vertebrates - complex tubular organs called kidneys

  . Unicellular organisms - contractile vacoule - collects and discharges wastes across cell membrane.
• Excertory structures

  . Protonephridia or flame cells - In platyhelminthes( flatworms eg planaria) rotifers,some annelids and the cephalochordate Amphioxus

  . Nephridia - Earthworms and other annelida

  .Malphighian tubules - most of the insects including cockroach

  . Antennal glands or green glands- in crustacea like prawns

  . Kidneys in vertebrates evolved to be highly specialised organs

  Metanephric kidney - most advanced , present in adults reptiles,birds ,mammals.
• Kidneys

  . Reddish brown, bean shaped

  . Situated between the levels of last thoracic ( T- 12) and third lumbar (L 3) vertebra

  . Close to the Dorsal inner wall of abdominal cavity Retroperotonial

  . Right kidney is slightly lower in position than the left kidney (Reason- Due to liver)
• Renal artery


  Branch of descending aorta that supplies oxygenated blood to the kidney
• Renal vein

  Tributor of inferior vena cava that collects deoxygenated blood from the kidney. Lowest urea content
• Size of kidney 10-12 cm length, 5-7 cm width and 2-3 cm thicc
• Weight of kidney 120-170g
• Hilum

  Notch towards the centre of inner surface of the kidney through which the ureter, blood vessels and nerves enter
• Pelvis


  Fine-shaped space where urine collects and then proceeds into the ureter
• Zones of the kidney

  • Outer cortex
  • Inner medulla
• Inner medulla

  • Medullary pyramids
  • Renal columns (columns of Bertini)
• Medullary pyramids

  Conical masses that project into the calyces
• Calyces

  Singular - calyx. Space where urine collects and then proceeds into the ureter
• Renal columns (columns of Bertini)


  The cortex extends in between the medullary pyramid as renal columns
• Functions of the kidney

  . Eliminate Nitrogenous waste ( like urea,uric acid,creatinine)

  . Water electrolyte balance (osmoregulation)

  . Acid- base balances (PH)

  .Hormones and enzymes- renin,erythropoietin and calcitrol ( vitamin deficiency D)

  . Removal of foreign substances and drugs

  . Maintain internal environment constant ( Homeostasis)
• Ureter

  . 2 ducts carry urine from the kidney to urinary bladder by peristalstic contractions

  . Opens obliquely into the bladder to prevent back flow of urine.
• Urinary bladder

  . Pear shaped structure with thick muscular wall lined by transitional epithelium that allows expansion.

  . Thick layer of smooth muscles called Detrusor muscle

  . Bladder stores urine temporarily and expels it out at intervals through urethra ( 350- 500 ml)

  . It's opening is quadrapled by sphicter muscles called urethral sphincters .

  . External sphincter - voluntary ( skeletal muscle)

  . Internal sphincter - involuntary ( smooth muscle)