Certified Nephrology Nurse Certification (CNN) Practice Exam 2025 – Comprehensive All-in-One Study Guide for Exam Success!

The movement of particles from an area of high concentration to an area of low concentration is known as diffusion. This process occurs naturally as particles tend to move towards a state of equilibrium, where concentrations are balanced across a space. It is a fundamental principle in biology and chemistry, relevant to many physiological processes.

For example, in the kidneys, diffusion plays a crucial role in the regulation of substances such as electrolytes and urea, allowing for the proper balance of these materials in the blood and urine. This process is passive and does not require energy, which distinguishes it from active transport mechanisms that move substances against their concentration gradient.

In contrast, osmosis specifically refers to the movement of water across a semipermeable membrane, while ultrafiltration involves the movement of water and small solutes through a filter, influenced by pressure. Contraction does not relate to particle movement in the context of concentration gradients. Understanding these distinctions is essential in nephrology and overall physiological processes.