What does a ”talking” cell say to a “listening” cell? The study of cell communication focuses on how a cell gives and receives messages with its environment and with itself. Cell signaling is part of a complex system of communication that governs basic cellular activities and coordinates cell actions.
The ability of cells to perceive and correctly respond to their microenvironment is the basis of development, tissue repair, and immunity as well as normal tissue homeostasis. Errors in cellular information processing are responsible for diseases such as cancer, autoimmunity, and diabetes.
In order to respond to changes in their immediate environment, cells must be able to receive and process signals that originate outside their borders.Individual cells often receive many signals simultaneously, and they then integrate the information they receive into a unified action plan. But cells aren't just targets. They also send out messages to other cells both near and far.
Neurotransmitters play a key role in cell signaling. Most cell signals are chemical in nature. For example, prokaryotic organisms have sensors that detect nutrients and help them navigate toward food sources. In multicellular organisms, growth factors, hormones, neurotransmitters, and extracellular matrix components are some of the many types of chemical signals cells use. These substances can exert their effects locally, or they might travel over long distances. For instance, neurotransmitters are a class of short–range signaling molecules that travel across the tiny spaces between adjacent neurons or between neurons and muscle cells. Other signaling molecules must move much farther to reach their targets. One example is follicle–stimulating hormone, which travels from the mammalian brain to the ovary, where it triggers egg release.
Hormonal signaling Cell communication over long distances via the bloodstream is known as endocrine (hormone) signaling. Some cells also respond to mechanical stimuli. For example, sensory cells in the skin respond to the pressure of touch, whereas similar cells in the ear react to the movement of sound waves. In addition, specialized cells in the human vascular system detect changes in blood pressure – information that the body uses to maintain a consistent cardiac load.
Thus, Cell signaling is most extensively studied in the case of human diseases and signaling between cells of a single organism. However, cell signaling may also occur between the cells of two different organisms. In mammals, early embryonic cells exchange signals with cells of the uterus. Bacteria exchange signals with each other in human epithelial and immune system cells.