“Relaxare” means to relax and is also used in this meaning by the field of medicine. The medical term relaxation usually refers to muscle relaxation. Disorders of relaxation can be a life-threatening condition, especially in the heart.
What is relaxation?
The medical term relaxation usually refers to muscle relaxation. Relaxation is a loanword from Latin, where the verb “relaxare” literally means to relax. The literal translation of relaxation is therefore “relaxation”. Depending on the contact, the term can develop different individual meanings in actual use. In the medical subfields of anesthesia, radiology and physiology, for example, the term relaxation is associated with different meanings. In physiology, relaxation refers to muscles and muscular organs such as the heart. Muscles are made up of individual filaments. During contraction, i.e., tension of a muscle, the actin and myosin filaments of the muscles slide into each other, thereby inducing a certain state of tension in the muscle, which is manifested in a shortening of the muscular structure. During relaxation, on the other hand, the contractile filaments slide apart, the muscular structure lengthens, and the muscle slackens. In anesthesia, the physician understands relaxation as the artificial relaxation of muscles, as it can be induced by the administration of drugs and is used preoperatively as well as intraoperatively. In radiology, on the other hand, the term relaxation stands for the development of magnetization in transverse and longitudinal directions, as is present in magnetic resonance imaging (MRI).
Function and task
Muscle contraction and relaxation have been documented in the sliding filament theory, which describes the individual processes involved in muscle fiber contraction and was codified by Huxley and Henson in the 1950s. Physiologically, muscle fibers are each composed of actin and myosin filaments. These contractile elements of muscle are interlocked. When the muscle contracts, the individual filament structures slide into each other. The filaments do not shorten themselves in the process; however, contraction causes the muscle as a whole to shorten. The structural basis for the filaments sliding into each other is the mobility of their filament heads made of myosin. Adenosine triphosphate attaches to the muscle, loosening the bond between the filament heads and the actin filaments. The head bends in this way and is thus able to slide along the actin filaments. The attachment of adenosine diphosphate to the muscle causes the filament heads of myosin to reattach to the actin filaments. The process derives the required energy from the cleavage of adenosine triphosphate into adenosine diphosphate and inorganic phosphates catalyzed by muscle myosin ATPases. Muscle contraction is subject to calcium-dependent control because only at high calcium concentrations can firm attachment of individual crossbridges to the actin filament occur. The higher the concentration, the stronger the binding. The tight binding is what makes the bridging possible in the first place, allowing the myosin and actin filaments to slide into each other. In this context, relaxation is achieved when the filaments slide apart again. Especially with respect to the heart muscle, alternating contraction and relaxation are vital. As soon as a part of the heart muscle no longer relaxes normally, there is a pathological relaxation disorder in the heart. In the context of anesthesia, the term relaxation retains its meaning from physiology, but in this field it usually refers to artificially induced muscle relaxation, such as can be brought about by the administration of muscle relaxants. These drugs reduce muscle tone by blocking stimulus transmission, acting directly in the central nervous system or intervening directly on the muscles. Direct-acting muscle relaxants inhibit the influx of calcium into the myoplasm of the muscle, preventing contraction.
Diseases and disorders
In diastolic relaxation disorder, part of the heart muscle does not relax normally. As a muscle, the heart pumps blood through the organism by means of contraction and relaxation phases, thus supplying the individual tissues and organs with important nutrients, messenger substances and oxygen.For the heart to meet this supply, the cardiac muscle must alternately contract and relax. When the heart muscle relaxes, the heart cavities fill with blood. Once the heart muscle contracts again, blood moves out of the heart cavities and is pumped into the bloodstream. In diastolic relaxation disorder of the heart, the heart cavities do not fill sufficiently with blood. Thus, during the subsequent contraction of the muscle, less blood is available to pass into the bloodstream. Such relaxation disorders are particularly common in the context of chronic blood pressure disorders. Less dangerous, but all the more common, is the relaxation disorder of skeletal muscles, which manifests itself as muscle tension. Muscle tension often occurs in the context of one-sided incorrect loading or overloading. This phenomenon can be accompanied by muscle pain, headaches and many other complaints. Stress and psychological strain can also cause permanently tense and hardening muscles. In addition to the above symptoms, stomach cramps and muscle spasms can occur. Trembling and twitching of the muscles can occur concomitantly. Tension in the body can also cause blood pressure to rise and gastric juices to become more acidic. Neurogenic spasticity, which causes increased permanent tension in the muscles, must be distinguished from muscle tension. Spasticity is caused by damage to the central nervous system. Often, the damage initially manifests as flaccid paralysis that progresses to spastic paralysis.
