osmoregulation

• loop of henle

  A) efferent arteriole

  B) afferent arteriole

  C) Bowmans capsule

  D) Glomerulus

  E) proximal convoluted tubule

  F) Loop of Henle

  G) descending limb

  H) ascending limb

  I) distal convoluted tubule

  J) collecting duct

  
• diagram

  A) active transport

  B) diffusion

  C) water impermeable

  
• water is lost in urine and sweat
• the kidneys role is to reabsorb water by osmosis to maintain the water potential of the blood
• the loop of henlé is the countercurrent multiplier mechanism
• the ascending limb is impermeable to water
• the descending limb is impermeable to ions
• in the ascending limb Na+ / Cl- actively transport into the medulla
• in the loop of henle Na+ / Cl- diffuse into the medulla
• in the descending limb the medulla has a low water potential so water moves into the medulla by osmosis
• the collecting duct has a higher water potential than the medulla so water moves into the medulla by osmosis
• water is reabsorbed into the capillary network
• a fennec fox has a longer Loop of Henle so it can reabsorb more water as there will be more time for active transport of ions into the medulla creating a larger water potential gradient so more water can be reabsorbed
• a frog doesn't have a loop of henle as it lives in water so can absorb it all the time