In medicine, adhesion describes the force of attachment between two or more organic layers or structures. For example, it enables blood cells to attach to the vessel wall and thus move independently of the blood flow. In a pathological sense, adhesion is an adhesion of sections of organs that may occur, for example, after surgery.
What is adhesion?
Adhesion allows blood cells, for example, to attach to the vessel wall and thus move independently of the blood flow. Adhesion (also known technically as adhaesio) is the attachment of molecules to a phase interface. The phase interface occurs between two layers or objects, each of which is relatively homogeneous and thus separates itself from its surroundings. For example, a phase interface exists between different tissue layers: Each layer has a different molecular structure and thus forms its own entity. The phase interface is not a physical, additionally existing, tissue layer but refers to the contact area between the molecules or tissues. The attachment force occurs due to physical interactions. Molecules attract, repel, and react biochemically with each other. In adhesion, these effects cause the molecules to attract each other.
Function and task
Adhesion plays an important role in countless processes in the human body. For example, some blood cells adhere to the walls of blood vessels to avoid being caught in the bloodstream. Some blood cells are also able to move along the vessel walls in this way. This benefits, among others, cells of the immune system, which can specifically seek out foci of infection. Recent research shows, for example, that a certain type of T cell not only moves along the inner wall of blood vessels, but can also migrate against the bloodstream. It is also documented that these T cells can even cross the blood-brain barrier. Despite some theories, the purpose of migration is not yet conclusively understood; however, it appears to be related to neurological diseases. In addition, platelet adhesion is essential for blood to clot. It is the organism’s response to injury and prevents excessive blood loss. During blood clotting, the platelets form a relatively stable association by adhering to each other. Other cells are also subject to adhesion. The tissue of a skin or organ consists of numerous cells that form a homogeneous mass. Different tissues adhere to each other to form the various structures in an organ, for example. Serosa, a reddish skin, also adheres to organs thanks to adhesion. In cell adhesion, the tissue cells attach to proteins of the extracellular matrix. The extracellular matrix is tissue in the intracellular space. It consists mainly of connective tissue and is involved in cell supply, signal transduction, and shaping. The adhesion of bacteria to mucous membranes is relevant to bacteriology. Many bacteria that spread through the air we breathe enter the human body through the mucous membranes. In the course of evolution, bacteria have therefore adapted to the molecular properties of mucous membranes. They are thus able to penetrate the organism and multiply in the body. Bacterial infections often – but not always – lead to the development of diseases.
Diseases and ailments
Adhesion also has pathologic significance in medicine. Inflammation can alter the adhesion of tissue layers. As a result, connective tissue adhesions form. Fibrin sticks the tissue together in the process. Fibrin is a protein that acts like a glue when activated and is normally involved in blood clotting, among other things. The adhesions that are formed in this way can take on either a planar or rod-like shape. Pathologic adhesions involve sections of organs that are contiguous and covered by the serosa. Adhesions and adhesions need not be immediately noticeable, but soon lead to functional limitations of the affected organs. One form of pathologic adhesion is adhesion belly or bride. “Bride” is derived from the French word “brider,” which means “to bind together.”In the case of adhesion abdomen, the adhesion is located in the abdominal cavity and forms a scar strand. Due to the location of the adhesion, medicine also refers to the condition as intra-abdominal adhesion. It can occur after surgery, for example; however, slightly more than 10% of brides form for other reasons. An adhesion abdomen does not have to pose an immediate danger to the organism and can be completely harmless even in the long term, if the pathological adhesion is limited mainly to supporting tissues. A possible complication that may develop as a result of adhesion in the abdominal cavity is adhesion ileus or bridenileus. Ileus is the medical term for an intestinal obstruction that carries the risk of rupture of the intestine. Less commonly, adhesion ileus results in restriction or interruption of blood supply. If part of the tissue no longer receives an adequate blood supply, the cells may die (necrosis). Adhesive ileus represents a mechanical ileus. Unlike functional ileus, mechanical ileus is often treatable with the help of surgery. Functional ileus may be due to poisoning or paralysis of the intestinal muscles, for example. The therapy depends on the specific cause. Physicians also occasionally refer to rod-shaped adhesions in joint capsules and other regions of the body as brides. This type of adhesion may limit the functionality of the affected joint.
