What is a primary function of ultrafiltration in dialysis?

Ultrafiltration in dialysis primarily focuses on the removal of excess fluid and certain small solutes from the blood, using a membrane that selectively filters based on size and concentration gradients. The primary function is to manage the balance of electrolytes and fluids in patients with compromised kidney function.

While excess electrolytes can be removed, ultrafiltration's main role specifically highlights fluid management, helping address conditions such as fluid overload. This is crucial for maintaining homeostasis in patients undergoing dialysis.

The other choices do not capture the central role of ultrafiltration accurately. Large solutes are not the primary concern of ultrafiltration, as this process mainly targets smaller dissolved substances along with excess fluid. Filtering out bacteria is not a direct function of ultrafiltration in dialysis, as the focus is on small molecules and fluids. Concentrating blood cells is contrary to the goals of dialysis, which is to remove unwanted waste and fluids rather than concentrate any components in the blood. Thus, the correct understanding aligns with the removal of excess electrolytes as a significant aspect of ultrafiltration's function in dialysis.