The muscle tissue is formed by a responsible mesodermal derivation of the movement of bodies that are parts of the body of a living being that play a role distinct from the bodies is formed by cells very elongated called muscle or myocytes fibers is a spindle cell that is spindle-shaped and multinucleated are eukaryotic cells that have more than one nucleus inside with the ability to contract very easily, in addition each of the muscle fibers is enveloped by a thin sheet of connective or connective tissue that is a heterogeneous set of organic tissues that share a common origin from the embryonic mesenchyme originating from the mesoderm.
Muscle tissue is tissue made up of cells capable of contracting, known as myocytes or muscle fibers. These have a protein framework formed by myosin and actin, with which they can contract from electrical, mechanical, physical, or chemical stimuli.
It is for this reason that muscle tissues are fundamental to the motor capacity of an organism. Within vertebrates, muscles represent around 40% of the body’s mass, and in many cases they are attached to the bone system through tendons.
Since the muscle cells that make up this type of tissue are highly specialized, their organelles are given different names than the organelles of another cell type. For example, the cytoplasm is known as sarcoplasm , the mitochondria are known as sarcosomes, and the smooth endoplasmic reticulum is known as smooth sarcoplasmic reticulum.
Types of muscle tissue
Muscle tissue is classified into three types:
- Skeletal muscle : Also known as voluntary or striated muscle, it is a tissue made up of long multinucleated and cylindrical cells that have a large number of mitochondria. This kind of tissue can be found in 90% of all muscles in the human body, attached to the skeleton within fascia and cartilage. These are usually contracted voluntarily, although they can be done involuntarily as a result of illness.
These are responsible for moving and moving the body, protecting the body, maintaining posture and generating heat, among other functions. They are usually classified into fusiform, unipeniform, bipenniform, multipenniform, wide, flat, short, bicep , digastric, and polygastric.
- Smooth muscle : Also known as non-voluntary or non-curved muscle, it is a tissue made up of mononucleated cells whose nucleus is in the center. This kind of tissue can be found around blood vessels , sex organs, and internal organs. The movement of these is controlled by the autonomic nervous system, so their contraction is not voluntary. Smooth muscles are generally classified into unitary smooth muscle tissue, such as those of the uterus , gastrointestinal tract, and ureter ; and multi-unit smooth muscle tissue, such as the iris , trachea, and nictitating membrane .
- Cardiac muscle : Also known as myocardium, it is a self-excitable (myogenic) tissue that works involuntarily without any nerve stimulation. This tissue covers the heart and is responsible for pumping blood throughout the body through the circulatory system.
This type of tissue has 5 properties: excitability, since it is capable of transmitting action potential; automatism, since it generates the impulses that cause its own contraction; contractility, since it is capable of contracting; relaxation, since it pumps calcium into the sarcoplasmic reticulum as if it were a single cell; and impulse conduction, since it conducts the impulses created by the cardiomyocytes of the pacemaker of the sinoatrial node through the electrical conduction system of the heart.