Parenhüümirakud

Parenhüümirakud, also known as parenchyma cells, are the fundamental cellular components found in various biological tissues, particularly in plants and some animals. In plants, they constitute the bulk of the plant body, filling soft tissues like those in roots, stems, leaves, flowers, and fruits. These cells are typically thin-walled, unspecialized, and living at maturity. Their primary functions are diverse and depend on their location within the plant. Photosynthesis is a key role for parenchyma cells in leaves, where they are packed with chloroplasts. In roots and storage organs, they serve as sites for storing food reserves, such as starch, and water. Parenchyma cells can also be involved in secretion, producing and releasing various substances. They possess the ability to dedifferentiate, meaning they can revert to a more primitive cell type, and then redifferentiate to form other cell types, which is crucial for plant growth and repair.

In animals, the term parenchyma is used to describe the functional tissue of an organ, as distinct from the supporting connective tissue (stroma). For example, the parenchyma of the liver consists of hepatocytes, which perform the liver's metabolic functions, while the stroma is made up of connective tissue and blood vessels. Similarly, in the kidney, the parenchyma includes nephrons, the functional units responsible for filtering blood and producing urine. The specific characteristics and functions of animal parenchyma cells vary greatly depending on the organ and the organism.