What process describes the movement of water across a capillary wall?

What process describes the movement of water across a capillary wall?

• A. Facilitated diffusion.
• B. Osmosis.
• C. Filtration.
• D. Pinocytosis.

Answer: (C)

The movement of water across a capillary wall is best described by filtration. Filtration refers to the process by which water and small solutes move through a semipermeable membrane, such as the capillary wall, driven by a pressure gradient. In the context of the capillaries, the blood pressure within the capillaries forces water and certain solutes out of the blood and into the surrounding tissue and interstitial fluid. This process is crucial for nutrient delivery and waste removal in biological systems. While osmosis involves the movement of water specifically in response to solute concentration gradients, it does not directly describe how water moves across capillary walls under pressure. Facilitated diffusion refers to the passive transport of molecules across a membrane via specific transport proteins, while pinocytosis is a form of endocytosis where the cell engulfs liquid. Neither of these processes specifically pertains to the movement of water through capillary walls driven by pressure, which is why filtration is the most accurate choice in this context.

The movement of water across a capillary wall is best described by filtration. Filtration refers to the process by which water and small solutes move through a semipermeable membrane, such as the capillary wall, driven by a pressure gradient. In the context of the capillaries, the blood pressure within the capillaries forces water and certain solutes out of the blood and into the surrounding tissue and interstitial fluid. This process is crucial for nutrient delivery and waste removal in biological systems.

While osmosis involves the movement of water specifically in response to solute concentration gradients, it does not directly describe how water moves across capillary walls under pressure. Facilitated diffusion refers to the passive transport of molecules across a membrane via specific transport proteins, while pinocytosis is a form of endocytosis where the cell engulfs liquid. Neither of these processes specifically pertains to the movement of water through capillary walls driven by pressure, which is why filtration is the most accurate choice in this context.