Final answer:
Phagocytosis is a cellular process that engulfs large particles like bacteria and is used by immune cells to destroy pathogens. Pinocytosis, in contrast, is the intake of extracellular fluid and its dissolved solutes, functioning almost continuously to absorb nutrients.
Step-by-step explanation:
Understanding Phagocytosis and Pinocytosis
Phagocytosis and pinocytosis are two forms of endocytosis, where cells engulf external substances. Phagocytosis, often referred to as "cell eating," involves the cellular intake of large particles such as bacteria or dead cells. During this process, the cell extends pseudopodia to surround and enclose the particle in a phagosome, which then fuses with a lysosome where the particle is digested. In the immune system, cells such as neutrophils utilize phagocytosis to engulf and destroy invading pathogens.
Conversely, pinocytosis, known as "cell drinking," involves the intake of extracellular fluid and the solutes dissolved within it. This process occurs continuously as part of cellular function, with the plasma membrane forming small vesicles that encapsulate the fluid and solutes, without merging with lysosomes. Both mechanisms are crucial for cellular function, with phagocytosis playing a significant role in the immune response and pinocytosis in nutrient absorption.