Question

7. Decide whether the following changes would increase or decrease peritubular capillary reabsorption (4 pts.) a. Increased colloid osmotic pressure in the peritubular capillary: increase b. Increased hydrostatic pressure in the peritubular capillary: decrease c. Increased colloid osmotic pressure in the renal interstitium d. Increased hydrostatic pressure of the renal interstitium

Answer 1

7. a) Increased colloid osmotic pressure in the peritubular capillaries represents the pressure exerted by proteins in the plasma. This implies that the water content is low (as protein pressure is high). Hence, this increases reabsorption of water into the peritubular capillaries.

b) Hydrostatic pressure implies the pressure exerted by water inside the capillaries. As pressure of water is already more, more water need not be taken into the capillaries. Hence, reabsorption decreases.

c) Increased colloid osmotic pressure in renal interstitium implies that more proteins are present in the interstitium than water. Due to this less water is reabsorbed. Hence, reabsorption decreases.

d) Increased hydrostatic pressure in the renal interstitium implies that more water is present in interstitium which can be reabsorbed. Hence, reabsorption increases.