Everyone knows that due to the presence of muscle tissue, it is possible to move the human body and its individual parts in space. But in our body there are still contracting organs. All of them perform functions indispensable for normal life.
What are organs
To begin with, let's figure out what such an organ is. This part of the body, which occupies a certain position, has a characteristic structure and performs one or a number of functions. A very important sign of any organ is that it contains several tissues at once.
There are four of them in the human body: epithelial, connective, muscle and nervous. All of them are formed by cells similar in structure and function.
Contracting human organs
The structure of contracting organs necessarily includes muscle tissue or cells that are close to it in properties. For example, collagen fibers are located in the skin. Thanks to this structure, it is capable of stretching and does not impede the implementation of various movements. All contracting organs can change their volume and length, after which they again return to their standard state.
Features of the structure of muscle tissue
Muscle tissue consists of individual contractile fibers called myofibrils. The latter are formed by threads of special proteins - actin and myosin. They are interconnected using transverse bridges. Nerve impulses excite muscle fibers, and they begin to contract. The essence of this process is that actin filaments are drawn between the myozone using transverse bridges. The length of the muscle fiber is reduced.
Striated muscle tissue
There are several types of muscle tissue. What contracting organs does striated or striated tissue form? These are facial and skeletal muscles, diaphragm, larynx, tongue, upper part of the esophagus. The fibers of this type of fabric are long and multi-core. Under the microscope, they look like alternating dark and light stripes.
Streaked muscle tissue is characterized by a high rate of contraction and relaxation, which are carried out consciously. After all, a person himself controls the movement of limbs and changes the expression on his face.
Heart muscle tissue
The heart is a special organ. He is constantly at work, because a person’s life depends on the frequency of his contractions. Therefore, this organ is also formed by a special type of striated tissue, which is called cardiac tissue. It has special sections in which individual fibers are interconnected. Such a structure provides a simultaneous contraction of the entire organ. A very important property of the heart muscle is conduction. It consists in the spread of excitation that has arisen in one area throughout the body. In special cells of the heart, pulses periodically occur that spread throughout the heart muscle and regulate the rhythm of its contractions. This property is called automatism.
Unstriated muscle tissue
The internal contracting organs are mainly composed of smooth, or unstriated tissue. This is the gastrointestinal tract, bladder, bronchi and lungs, walls of blood and lymph vessels. Spindle-shaped cells of smooth tissue are mononuclear and look uniform under a light microscope. Their characteristic feature is rather slow contraction and relaxation. Their activity is involuntary and does not depend on the will of man. For example, we cannot stop the contractions of the stomach or intestines.
So, the contracting organs of man have in their structure one of the varieties of muscle tissue. Coordinated automatic heart function is provided by a special variety of striated fibers. Smooth muscle tissue contracts slowly and involuntarily, forming the walls of internal organs. The movement of the body and its individual parts is ensured by striated fibers. They contract quickly and are controlled by man.