Loop of Henle

• What type of transport do cells use to move ions out of the loop of Henle?

  Active transport.
• What is the role of sodium and chloride ions in the loop of Henle?

  • They create concentration gradients that facilitate the movement of substances.
  • they allow urine to be more concentrated than blood
• What is the state of the filtrate entering the descending limb of the loop of Henle?


  It is isotonic with the blood.
• What is the permeability of the descending limb to sodium and chloride ions?

  It is not permeable to sodium and chloride ions.
• What is the permeability of the first section of the ascending limb of the loop of Henle to sodium and chloride ions?

  It is very permeable to sodium and chloride ions, allowing them to diffuse out.
• What is the state of the fluid at the top of the ascending limb?

  It is hypotonic to the blood.
• Describe the counter-current multiplier system

  • use of energy to produce concentration gradients that facilitate the movement of substances such as water
  • Counter-current flow- fluid flows in opposite directions in descending and ascending limbs, maintaining a concentration gradient
  • differential permeability- different permeabilities of the limbs to water and ions
• Describe the main function of the loop of henle

  • Creates an area of high solute concentration or low WP in medulla
  • produces urine which is more concentrated than the blood
  • Different areas of the loop have different permeabilities and this aids the way it functions
• true or false? the ultrafiltrate (the filtrate left after ultrafiltration) is less concentrated than the blood plasma

  TRUE- it's hypotonic to blood
• describe the processes that occur as blood enters and leaves the loop of henle

  • descending limb- filtrate entering is isotonic with blood. Permeable to water- water then moves out by osmosis into blood. This happens because the concentration of sodium and chloride ions decrease down the loop because of the activities of the ascending limb
  • at the bottom of the loop, filtrate is hypertonic to blood (more conc than blood)
  • ascending limb- first section- sodium and chloride ions move out by diffusion down a conc grad.
  • second section- sodium and chloride ions are actively pumped out. This increases the [Na and Cl-] in the medulla, needed for the kidneys to produce urine hypertonic to blood. The ascending loop is impermeable to water so water cannot follow these ions by osmosis, therefore the filtrate becomes very dilute again, hypotonic to blood

  
• what is the state of the filtrate at the bottom of the loop of Henle?

  It is hypertonic to blood