Muscular System: Roles and Functions

The ability to move is a very important aspect of organisms’ lives. Locomotion in organisms is normally controlled by the body muscles and the bones, and together with the two forms of what is known as musculoskeletal coordination; this structure conceals the interior body structures from injuries and also enhances mobility in the organisms. The muscles normally work in conjunction with the other body organs such as the brain and the central nervous system to bring about various forms of locomotion. The muscles normally consist of both flesh and fats that are normally stored in them; they are of varying dimensions, forms and perform varied functions in the body. Muscles perform varying activities in the body, for instance, the muscles in the feet and the legs control the movement of the legs while those in the heart control reflex heart activities such as heartbeat. The muscles normally consist of a large number of fascicles that are made up of numerous myofibrils. These myofibrils promote motion by contracting and relaxing. The myofibrils consist of sarcomeres which consist of myofilaments that are made of both myosins of actin. This paper will discuss the muscular system, its role in body function, mechanisms that promote its function, its effect on other body systems, as well as the current scientific research taking place on this muscular system.

A cell is a basic unit of life that consists of various organelles and chemical substances all wrapped up inside a cell membrane. The cells of the muscular system are known as muscle cells. Tissues refer to a collection of cells that are similar in structure and carry out the same function; the tissues of the muscular system are known as the muscle tissues. The tissues normally come together to form the organs. An organ refers to a group of either two or several tissues working together

to achieve the same objective. Some of the organs of the muscular system include the cardiac, smooth and the skeletal muscles. Just like the tissues, the organs also join up in order to form an organ system. An organ system refers to a group of either one or two organs performing the same function; examples include the circulatory system, muscular system, nervous system and the digestive system among others.

There are various types of muscles in the body and each one of them has a particular function to perform. The types of the muscles in the body include the smooth muscle which lines the interior body organs such as the blood vessels, cardiac which control the reflex movements in the heart and skeletal muscles which are normally connected to the bones (Watson, N.d). The cardiac muscles are found along the inner linings of the heart and they control the involuntary beating of the heart. This function is quite important because as a result of this, movement of blood in the blood vessels is checked, gases such as oxygen and carbon dioxide are exchanged and signals are sent from one part of the body to the next (Watson, N.d).

The smooth muscles are found in different organs of the body and play a role in the contraction of the void organs of the body such as the blood vessels and the and the respiratory canals, as a result allowing the flow of blood in the blood vessels, movement of food through the alimentary canal, excretion of wastes from the bladder and in the expulsion of the newborns out of the uterus. The last group of muscles is the skeletal muscles which provide the bones with stability and as a result giving sustenance to the whole body. Unlike the cardiac muscles and the smooth muscles which are involuntary, the skeletal muscles only act when triggered to do so. Moreover, the muscular system plays a role in homeostasis when they relax and contract a joint thereby enabling flexion and extension to occur and this normally occur through the sliding filament theory (Watson, N.d).

The Muscles consist of fibers which go through the whole muscle which are joined to each other by the connective tissues which normally consist of blood capillaries and nerves. The fibers consist of myofibrils that are positioned parallel to the fibers, a large number of mitochondria which produce energy through respiration for the muscle activities, a large amount of the smooth endoplasmic reticulum and a lot of cell nuclei (Hutchinson, 2002). The large number of nuclei is due to the clumping together of the myoblasts (Hutchinson, 2002). Usually, the amount of muscles is normally determined during the early days of a person’s life and it is normally determined by the myostatin which is normally produced in the muscle cells but becomes a hormone in the later days of a person’s life. Myostatin normally function by repressing the increase of muscles though research has shown that mutations can occur in the myostatin thereby resulting into extremely large muscles (Hutchinson, 2002).

The muscle fiber just like a cell has several parts and these include the sarcolema which functions as plasma membrane, sarcoplasmic reticulum which has the same function as the endoplasmic reticulum, sarcomeres which provide energy for the fiber and sarcoplasma whose functions can be equated to those of the cytoplasm (Hutchinson, 2002). The difference between these muscular cells and the other cells is that in the former has both the nucleus and the mitochondria are positioned under the plasma membrane and again sarcoplasmic reticulum runs in through the myofibrils. The skeletal muscles have been observed to show an alternating prototype and as a result leading to the formation of striated muscles. The stripes are normally an alteration between the A bands which are darkly colored and the lightly colored I bands. The Z disk divides the I bands while the A bands are normally divided by the H zone which goes through the middle part of the of the fiber known as the M line (Hutchinson, 2002). Moreover, the myofibrils consist of both thin filaments and the thick ones; the thick ones are made of myosin while the thin ones are made of troponin and the tropomysin which are all proteins (Hutchinson, 2002).

Both the cardiac and the heart look alike in the sense that both of them are striated and their cells also have sarcomeres containing both myosin and actin. The cardiac muscles have additional features to assist them in aiding the blood flow through the blood vessels and they include; the cardiac muscles have myofibrils that have branches which connect with those other ones in the nearing fibers via adherens junctions; these offer protection for the fibers even when the heart pumps with a lot of force (Hutchinson, 2002). The cardiac muscles also have little glycogen stored in them and hence is easily affected by any factor that interrupts the flow of oxygen to the heart thereby resulting in reduced respiration to provide energy for the beating of the heart. The muscles also have a lot of mitochondrion for respiration and again the action potential that directs the heart’s contraction moves in sequential manner from one fiber to the next, this is important since it prevents fibrillation due to the random heart beats (Hutchinson, 2002).

The smooth muscles on the other hand consist of individual cells which have the shape of the spindle. It is not striated but it has both thin and thick muscles and they are normally attached next to the plasma membrane by the intermediate filaments. Smooth muscles are voluntary in nature and do not depend on the stimulation of the motor skills (Thibodeau and Patton, 2008, p. 177). Research has shown that they can be stimulated by the neurons of the autonomic nervous system based on the neurotransmitter substance produced by the muscles. They can also contract if chemical compounds such as paracrine which are secreted in a region around it; it is also affected by oxytocin which makes the muscles to contract in order to promote the expulsion of the baby out of the uterus. The smooth muscles contract at a slower pace than the skeletal muscles though the contraction persists for a longer duration in the smooth muscles more in comparison to the skeletal muscles (Thibodeau and Patton, 2008, p. 178).

The muscular system is normally well adapted to its functions in a number of ways, for instance, the cardiac muscles have the adherens junctions which prevent the muscle fibers from being damaged even when it beats with a lot of force (Baldwin and Cheadle,1977); it also has a lot of mitochondria to provide it with energy and the action potential that enhances the contraction of the cardiac muscles normally move in a systematic manner from one fiber to the next via the gap junctions thereby preventing possible fibrillation (Baldwin and Cheadle,1977). The skeletal muscles have an increased number of mitochondria as well as a high rate of respiration in order to enhance the amount of energy for the muscle contractions. They also have a lot of fats in the form of glycogen which they can break down to release the energy for the cells; the smooth muscles too have a high deposit of fats to provide it with sufficient energy (Baldwin and Cheadle, 1977).

The body consists of various organ systems that function either in isolation or in conjunction with the others in the body. Basically, the muscular system works hand in hand with the other system to make the body functional, for instance, the cardiac muscle constitutes the myocardium and it aids the flow of blood around the body through the contraction of the cardiac muscles (Anonymous. N.d). The muscular system plays role in the digestion of food through the smooth muscles that contract and relax, and as a result breaking down the food into smaller particles. The smooth muscles found along the uterine walls are important in the birthing process because through their contraction, the delivery of the baby is made possible. The muscular system also works together with the nervous system so as to enhance the contraction of the body muscles (Anonymous. N.d).

One of the current studies being done on the muscular system is on genetic mutation that causes an incapacitating muscle health complication known as myasthenia that is characterized by serious weakness of the muscles (Debilitating condition traced to mutation – Muscular System – myasthenia, 2003). This condition results from loss of communication between the nerve and the muscle due to interference at the point where the nerve and the muscle join. Research has shown that the condition is as a result of a mutation that prevents the muscle from responding to the impulses transmitted via the nerves (Debilitating condition traced to mutation – Muscular System – myasthenia, 2003). However, the therapy for the condition isn’t known yet but this discovery proves quite useful in the research for a possible curative procedure since its cure has not been found yet.

The muscular system is important in the body since it allows movement in organism in order for them to acquire food and escape danger among other things. The muscular system consists of different types of muscles which include the cardiac, smooth and skeletal muscles. The muscular system is normally affected by a number of health conditions which at times results into its complete incapacitation.


Anonymous. (N.d). How Does the Muscular System Help the Other Body Systems? 2010, Web.

Baldwin, K. and Cheadle, W. (1977). Time course: adaptations in cardiac and skeletal muscle to different running programs. Web.

Debilitating condition traced to mutation – Muscular System – myasthenia. (2003). USA Today (Society for the Advancement of Education). Web. 

Watson, F. (N.d). What are the Functions of Muscles in the Body? 2010. Web.

Hutchinson, L. (2002). Muscular System: Animal Sciences. Web.

Thibodeau, G. and Patton, K. (2008). Structure & function of the body. Mosby/Elsevier.

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