Collecting Duct and ADH PDF

Collecting duct and ADH Anti-diuretic hormone (ADH) If the kidneys fail, a range of treatments are available: controls the permeability of the...

Collecting duct and ADH Anti-diuretic hormone (ADH) If the kidneys fail, a range of treatments are available: controls the permeability of the collecting duct to water. When it Medication can be used to control K+ and Ca2+ levels to help balance fluids. is more permeable, more water is A low-protein diet can be used to reduce the number of excess amino acids reabsorbed to the blood and less and thus the urea made. water is excreted as urine. Drugs can be used to lower blood pressure. When blood water potential is lower A dialysis could be used to artificially remove urea from the blood. than the set point, osmoreceptors in the hypothalamus detect the A kidney transplant could be used to replace the kidney that is no longer change. functioning with a healthy one. The posterior pituitary gland releases ADH into the bloodstream. Dialysis ADH attaches to receptors on the cells of the collecting duct. Aquaporins (vesicles with water channels) fuse with the membrane The collecting duct passes through a hypertonic region of the of the cells next to the lumen of the medullla. Permeability of this tubule is under hormonal control in collecting duct. order to control the volume of water lost in urine. Water moves into the cells by osmosis and then passes from the cells into the bloodstream, raising the water potential of blood. A low volume of concentrated urine is produced. As the water potential of the blood A dialysis machine is effective for the following reasons: increases, the production of ADH decreases. Less ADH leads to a Temperature at 40 °C to increase the rate of diffusion and maintains patient body less permeable membrane of the temperature. collecting duct. This will lead to the collecting duct losing less water by A large number of strands of dialysis tubing increases the surface area where osmosis and the production of a diffusion can take place. large volume of dilute urine. Dialysis tubing is a semipermeable membrane with pores that only allow small This detection of a change away molecules eg urea, water, salt through. from normal conditions and Dialysis fluid has no urea to give a concentration gradient; water leaves by consequent processes to move osmosis. There is no concentration gradient for glucose and so it doesn’t leave the conditions back towards normal is blood. called negative feedback. Fresh dialysis fluid maintains a concentration gradient. Counter current flow of blood and fluid maintains a concentration gradient.