Body processes

Cell Communication – Function, Task and Diseases

Cell communication

Cell communication is a process composed of intercellular and intracellular communication. Information is first exchanged between the cells via messenger substances . Within the cell, the signal is then passed on and even amplified via receptors and secondary messengers.

What is Cell Communication?

Cell communication is used to transmit external stimuli through signal transmission between cells and within cells. The external transmission of signals takes place via special messenger substances such as hormones , neurotransmitter-mediated or ion-mediated electrical stimulus transmission, cell-bound surface molecules or high-molecular substances in the intercellular space.

The signals reach the interior of the cell via receptors or so-called gap junctions and trigger a cascade of reactions there, depending on the transmission path. In this way, second messengers (secondary messenger substances) are formed in the cell, which forward the signal to the target site and at the same time amplify it. A signal amplification takes place because an external signal results in the formation of a large number of second messengers.

In contrast to intercellular communication, in intracellular communication the signals are processed in the cell and converted into a reaction. Here the information is not transmitted from cell to cell, but forwarded by chemical messengers with amplification to the cellular destination. This entire process of intracellular communication is also referred to as signal transduction.

function & task

In multicellular organisms, intracellular communication processes both the signals transmitted by extracellular messengers and by external stimuli ( hearing , sight , smell ). Signal transduction regulates important biological processes such as gene transcription , immune response , cell division , light perception, smell perception or muscle contraction. 

The start of intracellular communication is triggered by extra- or intracellular stimuli. The extracellular triggers include hormones, growth factors, cytokines, neurotrophins or neurotransmitters . Furthermore, environmental influences such as light or sound waves are extracellular stimuli.

Intracellularly, calcium ions often trigger the signal transduction cascades. The extracellular signals are first picked up by receptors located in the cell or in the cell membrane . A distinction is made between cytosolic and membrane-bound receptors.

Cytosolic receptors are located inside the cell in the cytoplasm . They represent points of attack for small molecules that can easily pass through the cell membrane. These include steroids , retinoids, carbon monoxide and nitric oxide. After activation, steroid receptors ensure the formation of second messengers, which are responsible for transcription processes.

The membrane-bound receptors are located in the cell membrane and have both extracellular and intracellular areas. During signal transmission, the signaling molecules dock to the extracellular area of ​​the receptor and, by changing its conformation, ensure that the signal is passed on to the intracellular area. Biochemical processes then take place there, which form a cascade of second messengers.

The membrane-bound receptors are divided into three groups, the ion channels, the g-protein-coupled receptors and the enzyme-coupled receptors. The ion channels are in turn ligand-gated and voltage-gated ion channels. These are transmembrane proteins that are activated or deactivated depending on the signal and thereby change the permeability for certain ions.

A g protein-coupled receptor, when activated, causes the G protein to break down into two components. These two components are active and ensure that the signal is passed on by forming certain second messengers.

Enzyme-coupled receptors are also membrane-bound receptors that release the enzymes bound to them during signal transmission. Thus there are six classes of enzyme-linked receptors. Depending on the activated receptor, the corresponding signals are converted. For example, the receptor tyrosine kinase represents the receptor for the hormone insulin . The effect of insulin is thus mediated via this receptor.

Some cells are connected via so-called gap junctions. Gap junctions are channels between neighboring cells and are a form of intracellular communication. When a signal reaches a particular cell, the gap junctions ensure its rapid propagation within the neighboring cells.

Diseases & Ailments

Disorders of intracellular communication (signal transduction) are possible at many points in the signal transmission process and can have different health effects. Many diseases are caused by insufficient effectiveness of certain receptors. 

If the immune cells are affected, immune defects occur as a result . Autoimmune diseases and allergies are caused by faulty processing of intracellular signal transmission processes. But diseases such as diabetes mellitus or arteriosclerosis are often the result of ineffective receptors. For example, if you have diabetes, you may have enough insulin. However, due to missing or ineffective insulin receptors, there is insulin resistance here . As a result, more insulin is produced. Eventually, the pancreas may become exhausted.

Many mental illnesses can also be traced back to disruptions in intracellular cell communication, because in many cases the signal transmission is not sufficiently guaranteed due to insufficiently effective receptors for neurotransmitters.

Neurotransmitters also play an important role in mental illness. For example, it is being investigated which disturbances in the complex processes of signal transmission can lead to illnesses such as depression , mania , bipolar disorders or schizophrenia .

Genetic causes can also lead to a disruption in intracellular communication. A particular example of inherited disorders relates to gap junctions. As already mentioned, the gap junctions are channels between neighboring cells. They are formed by transmembrane proteins, the connexin complexes. Several mutations of these protein complexes can lead to severe hearing loss or even deafness . Its cause lies in the defective functioning of the gap junctions and the resulting disruption in cell communication.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.