Which type of endocytosis can be described as "cell drinking"?

Pinocytosis is often referred to as "cell drinking" because it involves the uptake of small amounts of extracellular fluid along with dissolved nutrients and solutes. In this process, the cell membrane invaginates, forming small vesicles that incorporate the fluid. This mechanism allows cells to sample their environment and intake various substances that are present in the fluid they are engulfing.

In contrast to phagocytosis, which is the engulfment of larger particles or cells ("cell eating"), pinocytosis targets the fluid phase and is nonspecific regarding the substances it internalizes. Receptor-mediated endocytosis involves specific interactions between receptors on the cell surface and particular molecules, making it distinct from the more generalized nature of pinocytosis. Exocytosis, on the other hand, refers to the process of expelling materials from the cell, which does not align with the concept of "cell drinking." Thus, pinocytosis accurately captures the essence of this particular form of endocytosis.