There are three main types of muscles in the human body. They´re strong elastic tissues that contract to allow different parts of the body to perform movement, such as jumping, walking, breathing, digesting food, blinking, etc. Most of muscle contractions occur without any conscious thought and is essential for survival, like cardiac muscle (peristalsis). Muscle contractions can also be voluntary, such as the movements of hands and fingers. Approximately 40 to 50% of the human body is made up of muscle tissue.
The muscular system is composed of cells known as fibers. All muscle tissue possesses properties, including contractility, extensibility, and elasticity which allow the body to perform its various movements. The combination of bones, joints, and skeletal muscles produces movements, including running, walking, bending, eye movement, etc. Muscle contraction also fulfills other important functions, such as posture and heat production. Approximately 85% of body heat is produced by muscle contraction.
Skeletal muscles vary in size and shape. They range from tiny strands of muscle like the stapedium muscle in the middle ear to large muscle fibers, such as the muscles in the thigh. Skeletal muscles depend upon the direct control of the nervous system. They´re made of bundles of fascicles which are surrounded by connective tissue called epimysium; each fascicle contains individual cells called muscle fibers, which are among the largest cells in the human body (up to 30 cm long), extending the full length of the muscle.
Each individual muscle cell is surrounded by connective tissue known as endomysium. A single muscle fiber is made of bundles of myofibrils and possesses multiple nuclei. The connective tissue coverings offer protection and support for the cells, allowing to withstand the forces of contraction. Before any skeletal muscle exerts contraction, it has to receive an impulse from a nerve cell. Tissue surrounding the muscles contains blood vessels and nerve cells which transmit signals to the muscle. When signals are received, calcium is released, causing muscle contraction.
Smooth muscle is found in the walls of internal organs, including the gastrointestinal tract, uterus, blood vessels, and bladder, and performs slow and rhythmically contractions needed to maintain these systems. Smooth muscle is made up of elongated cells arranged in bundles, containing a single nucleus. Inside the intestinal tract, smooth muscles produce constrictions and wave-like motions to move ingested food along. The smooth muscles are controlled by the autonomic nervous system, meaning, they cannot be controlled consciously, thus, they act involuntarily.
Cardiac muscle is found exclusively in the walls of the heart (myocardium). This type of muscle continuously generates strong contractions which pump blood throughout the human body. Cardiac muscle cell contains a single nucleus, similar to the smooth muscle, and is also striated, like skeletal muscle. Cardiac muscle is controlled by the autonomic nervous system, meaning, it is involuntary. Unlike other muscles, the cardiac muscles continuously contracts and relaxes without stopping to maintain blood circulating throughout the human body.
The three main types of muscles are essential for performing the daily movements which allow us to perform a variety of functions, including respiration, digestion, circulation, and body temperature. To maintain the muscular system in optimum shape it is very important to follow a healthy diet, as well as to engage in daily activities, so as to provide the necessary strength, contractility, and elasticity to your muscles.
The three types of muscles are essential for performing the daily movements of our bodies, allowing us to perform a variety of functions, including respiration, digestion, circulation, and body temperature. To maintain these three types of muscles in optimum shape, it is essential to follow a healthy diet, as well as to engage in daily activities which can confer strength, contractibility, and elasticity to these muscles.