Cell process
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A cell process is a component of a cell , which is a protuberance of the cell membrane or a special formation on the cell membrane.
These can be extensions of the cell of different lengths and shapes or, compared to membrane proteins, large protein complexes that are anchored in or on the cell membrane and serve special functions.
Forms of cell processes
Cilia , flagella and pseudopodia serve individual learning for locomotion. Cells in multicellular living beings can also use it to move about ( cell migration ). Some epithelial cells also use kinocilia or cilia to generate fluid flows, for example in the bronchial passages or in the fallopian tubes .
Microvilli enlarge the cell surface or form filter funnels, just as the plant root hairs serve to absorb food.
Individual cilia can act as a mechano or chemosensor for a cell. They are also important in embryonic development for the formation of differentiated tissues. The nodal cilia of the primitive knot play a special role in animals , the stroke of which determines the direction of the periembryonic flow. As a result, signal proteins (such as Nodal ) are expressed differently on the sides , which ultimately leads to the lateralization of internal organs.
Cilia appear with specific features in sensory cells, for example in an olfactory cell in the mucous membrane ( olfactory epithelium ) of the nose or a visual cell in the retina of the eye. The extensions of the mechanoreceptive hair cells in the cochlea of the inner ear carry several stereovilli in addition to a cilia , as well as those in the equilibrium organ and those in the lateral line organs .
Of particular importance for the development of a nervous system are the cell processes formed by nerve cells , with which neurons selectively establish contacts with other individual cells. These processes can serve as neurites, primarily for the ( efferent ) transmission of neuronal signals, or as dendrites for the ( afferent ) reception of signals from other cells or of stimuli - for example in those neurons that are also olfactory cells.
Further cell processes are pilus , lamellipodium , undulipodium , rhabdomer and also a pollen tube .