What is the definition of merocrine secretion?

Merocrine secretion is characterized by the process of releasing substances through exocytosis from secretory vesicles. This method allows cells to secrete their products without losing any part of their cellular structure. During exocytosis, vesicles containing the secretory product fuse with the cell membrane and release their contents into the extracellular space. This mechanism is commonly seen in glands such as sweat and salivary glands, where the integrity of the cell remains intact after secretion.

The other options describe different types of secretion or cellular processes. The option that refers to the breakdown of the entire cell pertains to holocrine secretion, where the cell disintegrates to release its contents. The option related to direct hormone release into the bloodstream describes endocrine secretion, which is a different mechanism that bypasses the cellular secretion process. The option about cells absorbing substances is more aligned with the process of endocytosis rather than secretion. Understanding these differences is crucial for identifying and recognizing various secretion mechanisms in human physiology.