Final answer:
Damage to the glomerulus results in a decrease of colloid osmotic pressure in the glomerular capillaries while also reducing the net filtration pressure. Hydrostatic pressures in the Bowman's capsule and glomerular capillaries may not be directly affected.
Step-by-step explanation:
When the glomerulus is damaged, filtration membrane integrity is compromised, allowing large molecules like red blood cells and large proteins to escape into Bowman's capsule. This disrupts the colloid osmotic pressure normally maintained by these large solutes within the glomerular capillaries, as they contribute to the retention of fluid within the blood vessels by osmosis. Consequently, when these large molecules leak into the urine, they leave behind less solute in the blood, diminishing the blood's ability to draw water back, therefore reducing the colloid osmotic pressure within glomerular capillaries.
Since osmotic pressure is responsible for attracting water towards solutes, its reduction would mean there would be less reabsorption of water back into the capillaries from Bowman's space, potentially increasing urine output and volume. Additionally, this would also result in a decrease in net filtration pressure (NFP) because colloid osmotic pressure is a key component that offsets the glomerular hydrostatic pressure to determine NFP. However, the hydrostatic pressure in the Bowman's capsule or the glomerular capillaries may not necessarily decrease directly because of the damage to the glomerular filtration membrane, although systemic changes could eventually modify these pressures as well.