What is the primary method by which materials such as O₂, CO₂, and nutrients are exchanged between blood and the surrounding tissues
A)passive diffusion of substances across the capillary wall down their concentration gradients
B)active transport of materials across the capillary wall
C)osmotic pressure drawing water and solutes out of the capillary, and bringing these dissolved nutrients into contact with the tissue cells
D)the processes of ultrafiltration and reabsorption

Question

Quizplus · Accepted Answer

The primary method of exchange between blood and surrounding tissues is passive diffusion of substances across the capillary wall down their concentration gradients. This occurs due to the small size and thin walls of capillaries, which allow for easy exchange of molecules and gases between the blood and the tissues. Active transport may occur for some specific molecules, but it is not the primary method of exchange. Osmotic pressure plays a role in drawing water and solutes out of the capillary, but it is not the primary method of exchange either. Ultrafiltration and reabsorption are related to the formation of urine in the kidneys, not to the exchange of materials between blood and tissues.

What Is the Primary Method by Which Materials Such as O₂