The Muscles As a whole, they form the organ system of the muscles that enable the human body to move. Muscles are cells that have the ability to contract in response to a particular stimulus, consuming energy as sugar and oxygen from the blood.
They are divided Muscles roughly into the skeletal muscles of the locomotor system, the smooth muscles of the internal organs, and the heart muscle.
While skeletal muscles can be controlled at will, the smooth muscles work largely independently of human intentions. In the digestive system, for example, the smooth muscle cells do their work at their own pace and cannot be influenced by a person's will.
Similarly, it is hardly possible to let the heart beat at will because the heart muscle tissue is also not subject to a person's will.
The Muscles of the musculoskeletal system usually consist of a muscle belly and two tendons, which are usually attached to bones or connective tissue sheets.
Some muscles are also made up of two or more muscle bellies with a corresponding number of tendons. The muscle belly is surrounded by a connective tissue covering and is divided into numerous bundles of muscle fibers. The core of every muscle fiber is a contracting protein network consisting mainly of three proteins, myosin, actin and troponin.
The actin forms a system of short fibers that resemble the stiles on a ladder. Myosin proteins are fixed between two actin bars with the help of springy troponin proteins. In response to the corresponding nerve signal, the myosin proteins climb the actin bars like a real ladder and the muscle can thus shorten.
Heart muscle cells differentiate themselves from the other types of muscle in that they can in some cases also directly feed on fats and cholesterol from the bloodstream and generate electrical impulses of themselves at a certain heart rate and pass them on to all other cells, cell by cell, so that this Heart can beat as a whole and in a coordinated manner.
By building the Muscles A muscle can only conditionally shorten or relax. To enable movement of the limbs and the body and trunk in all directions, the muscles of the musculoskeletal system are arranged in opposing parts.
The two-bellied arm muscle is responsible for the flexion in the elbow joint, while the arm muscle with the three muscle bellies performs the extension in the elbow joint as its counterpart. Another peculiarity of how muscles work is that a muscle rarely only takes on one task. Usually several joints are moved in different directions by the same muscle.
The two-headed arm muscle not only bends the arm in the elbow joint, it also lifts the arm with its longer muscle belly away from the body or guides it back towards the body with its shorter muscle belly. It also helps with swinging the arm forward and turning the whole arm inward. It is also the strongest muscle that rotates the forearm inwards.
The smooth muscles, on the other hand, have the function within the body of joining together in the internal organs, including the blood vessels. One of the peculiarities of smooth muscle cells is that they can not only join together and relax, but can also remain in a joined state.
The most common complaints that can occur in the skeletal muscles are muscle hardening, pulled muscles together with sore muscles or muscle cramps.
Diseases that can occur in the muscles include a variety of genetically caused muscle weakness diseases such as Becker syndrome, in which the body cannot properly produce an essential protein in the muscle and the muscle becomes inoperable and weak as a result.
Many metabolic or nerve diseases such as paralysis show up in the muscles. There are also anti-immune diseases caused by the body's own immune system. The other two types of muscles, on the other hand, are affected by other diseases. Inadequate oxygen supply can range from heart pain to heart attack.