The body of all animals, including humans, consists of four types of tissue: epithelial, nervous, connective and muscle. The latter will be discussed in this article.
Types of muscle tissue
It is of three types:
The functions of muscle tissue of different species are somewhat different. Yes, and the structure too.
Where are muscle tissues in the human body?
Muscular tissues of different species occupy different locations in animals and humans. So, from the heart muscles, as the name implies, the heart is built.
Skeletal muscles form from the striated muscle tissue.
Smooth muscles line the inside of the cavity of organs that need to contract. This, for example, the intestines, bladder, uterus, stomach, etc.
The structure of muscle tissue of different species varies. We will talk about it in more detail later.
How does muscle tissue work?
It consists of large-sized cells - myocytes. They are also called fibers. Muscle tissue cells have several nuclei and a large number of mitochondria - organoids responsible for energy production.
In addition, the structure of muscle tissue in humans and animals involves the presence of a small amount of intercellular substance containing collagen, which gives the muscles elasticity.
Let's look at the structure and functions of muscle tissues of different types separately.
The structure and role of smooth muscle tissue
This tissue is controlled by the autonomic nervous system. Therefore, a person cannot consciously contract muscles built from smooth tissue.
It is formed from mesenchyme. This is a type of embryonic connective tissue.
This fabric shrinks much less actively and quickly than striated.
Smooth tissue is constructed from spindle-shaped myocytes with pointed ends. The length of these cells can be from 100 to 500 micrometers, and the thickness is about 10 micrometers. The cells of this tissue are mononuclear. The nucleus is located in the center of the myocyte. In addition, organoids such as agranular EPS and mitochondria are well developed. Also in the cells of smooth muscle tissue there is a large number of inclusions from glycogen, which are stocks of nutrients.
The element that provides the reduction of muscle tissue of this type are myofilaments. They can be built from two contractile proteins: actin and myosin. The diameter of myofilaments, which consist of myosin, is 17 nanometers, and those that are built of actin are 7 nanometers. There are also intermediate myofilaments, the diameter of which is 10 nanometers. Orientation of myofibrils longitudinal.
The composition of muscle tissue of this species also includes the intercellular substance from collagen, which provides a link between individual myocytes.
The functions of muscle tissue of this type:
- Sphincter. It consists in the fact that from smooth tissues circular muscles are arranged that regulate the transition of contents from one organ to another or from one part of an organ to another.
- Tow truck. It consists in the fact that smooth muscles help the body remove unnecessary substances, and also take part in the birth process.
- Creating a lumen of blood vessels.
- The formation of the ligamentous apparatus. Thanks to him, many organs, such as, for example, the kidneys, are held in place.
Now let's look at the following type of muscle tissue.
Striated
It is regulated by the somatic nervous system. Therefore, a person can consciously regulate the work of muscles of this type. Skeletal muscles are formed from striated tissue.
This fabric consists of fibers. These are cells that have many nuclei located closer to the plasma membrane. In addition, they contain a large number of glycogen inclusions. Organoids such as mitochondria are well developed. They are located near the contractile elements of the cell. All other organelles are localized near nuclei and are poorly developed.
The structures by which the striated tissue contracts are myofibrils. Their diameter is from one to two micrometers. Myofibrils occupy most of the cell and are located in its center. Orientation of myofibrils longitudinal. They consist of light and dark discs that alternate, which creates a transverse "striping" of the fabric.
The functions of muscle tissue of this type:
- Provide movement of the body in space.
- Responsible for the movement of body parts relative to each other.
- Able to maintain body posture.
- Participate in the process of temperature regulation: the more actively the muscles contract, the higher the temperature. When freezing, striated muscles can begin to contract involuntarily. This explains the trembling in the body.
- Perform a protective function. This is especially true of the abdominal muscles, which protect many internal organs from mechanical damage.
- Act as a depot of water and salts.
Heart muscle tissue
This fabric is similar at the same time to striated and smooth. Like smooth, it is regulated by the autonomic nervous system. However, it is contracting as actively as striated.
It consists of cells called cardiomyocytes.
The functions of muscle tissue of this type:
- It is only one: ensuring the movement of blood throughout the body.