Kidneys

• Regions of the kidney

  • Cortex
  • Medulla
  • Pelvis
• • Renal artery
  • Renal vein
  • Ureter= transports urine to the bladder
• Ultrafiltration 

  Glomeruls is supplied with blood by a wide afferent arteriole from the renal artery.

  Blood leaves through a narrower efferent arteriole so there is high hydrostatic pressure in capillaries of the glomerulus.

  This forces blood out the capillary wall.

  Substances that leave are glucose, amino acids, ions, water and urea.
• Structure of a nephron

  • Bowmans capsule
  • Proximal convoluted tubule.
  • Descending limb of the loop of Henle.
  • Ascending limb of the loop of Henle.
  • Distal convoluted tubule.
  • Collecting duct.
• Reabsorption

  • Glucose and amino acids diffuse back into capillaries by active transport from proximal convoluted tubule.
  • Water moves by osmosis from loop of Henle and collecting duct.
  • Ions diffuse from distal convoluting tubule.
• Adaptations of bowmans capsule

  1. Blood forced through the capillary wall made of endothelium.
  2. Passes through a basement membrane which is made up of collagen fibres. Most of the plasma contents pass through except blood cells and large proteins.
  3. Wall of bowmans capsule involves cells called podocytes which have extensions called pedicels that wrap around the capillary.
• Adaptations of proximal and distal convoluted tubule

  • Microvilli= increases surface area
  • Many mitochondria= provide ATP for active transport.