The Muscular System | Mechanism behind Locomotion

The muscles are an integral part of the human anatomy essential for locomotion or the ability for an individual to transport himself from one site to another. They are responsible for movements on a position, mixing of food in the stomach, pumping of blood, making sounds, speaking and regulation of body temperature. The muscles also contribute to the appearance of an individual; it could make you look sexy and attractive especially if you have a six-packs or you could look beta-male with low muscle tone. You can imagine a situation in which we have no muscles but a broad floppy mass of skin worn over the skeletal structures. Without muscles, the body wont be able to participate in a lot of life activities.

The muscles of the body are responsible for posture and appearanceHumans have more than 600 muscles which are classified into different types on the basis of human's ability to control them, presence or absences of striations and depending upon situation.

Classification of Muscles

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The muscles of the body classified on the basis of human ability to control them can be distinguished by the of accessibility of these muscles. There are two types of muscles under this classification; voluntary and involuntary muscles Voluntary muscles can be controlled at will. Examples of these muscles include the bicep brachii of the arm, rectus abdominis of the abdomen, obicularis oris of the eyes etc. They are majorly muscles of the body responsible for movement in man and are usually palpable (touchable). All skeletal muscles are voluntary muscles. On the other hand, involuntary muscles are muscles with have the ability to move and create an effect but their movement are not controlled by will. No one can control his heart and no one can control his intestines. The muscles that make up these organs are involuntary muscles.

Striation as seen in skeletal muscle under a microscope

Classification of muscles based on striation is dependent on the presence of cross pattern on the muscles. These striation can only be observed when muscle tissues are studied under a microscope. Skeletal muscles and muscles of the heart are striated muscles while smooth muscles are non striated muscles. These striation patterns on the muscle fibers are caused by differences in the density and size of protein filaments of the muscles. These protein filaments are actin, myosin and troponin; they are responsible for contraction and relaxation of muscle fibers, this in turns causes movement.

The final basis of classifying muscles is based on situation. These muscles include: Skeletal muscles, Cardiac muscles and Smooth muscles. 30 - 40% of the body mass is made up of skeletal muscles. These muscles are striated and voluntary (they can be controlled by will). They are the most abundant of the three types of muscles on the basis of situation. The fiber of the skeletal muscle are arranged parallel. These muscles supplied by somatic nerves; somatic nerves are a set nerves associated with voluntary control of the skeletal muscles. Skeletal muscles are attached to bones in conjunction with the bone, they cause locomotion, they are also responsible for maintaining the body posture. Cardiac muscles form the musculature of the heart and are adapted to contraction and relaxation through out life. They are supplied by autonomic nerves and can not be subjected to human control. They are striated and pump blood into blood vessels. Smooth muscles are deep muscles which can not be seen or touched unless in surgical opening of the human body. They are major constituents of the esophagus, stomach, intestines, blood vessels, bladder, etc. The cells of these muscles are spindle in shape and can not be controlled.

The table below shows a few comparism between skeletal, cardiac and smooth muscles.

Feature	Skeletal Muscle	Cardiac Muscle	Smooth Muscle
Location	In association with bones	Heart	Internal Organs
Striation	Present	Present	Absent
Fatigue	Possible	Impossible	Impossible
Tetanus	Possible	Impossible	Possible
Contraction Speed	Fast	Intermediate	Slow
Control	Voluntary	Involuntary	Involuntary
Innervation	Somatic Nerves	Autonomic Nerves	Autonomic Nerves

Functions of the muscles

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The functions of the muscles have been mention severally paragraphs above and its importance to everyday activities has been established. Below is a list of the functions of the muscles and the muscular system:

• Role in chewing food and mixing with saliva.
• Mechanical mixing and grinding of food, seen in muscles of stomach.
• Aid mobility and movement non-positional change movement.
• They enable vaginal penetration for deposition of sperm, seen in muscles of the penis.
• Muscles help to produce heat for maintaining body temperature.
• They help maintain a good posture.
• They contribute to the appearance of the face and body.
• Muscles of the heart help pump blood in the body.
• Muscles aid complex activities such as writing, picking objects etc.
• Muscles help burn fat when exercised

Muscles, energy utility and heat production

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The muscles is able to perform it functions with the help of energy in form of ATP. This ATP is gotten from fuels such as glucose, glycogen and fatty acids. When ATP is broken down, the muscles contract and produces water and heat. In times of cold, this mechanism is adopted by the body; it begins to shiver and in the process, ATP is broken down, heat is produced and the body temperature is brought back to normal. Energy usage is higher during physical exercise, this causes more fuels such as fat to be broken down to keep the demand of ATP for energy, this is the mechanism behind exercising and loosing weight. The skeletal muscles use oxygen in the process of ATP utilization, this is also the reason why we breath heavily during physical exercise; the heart pumps faster to get enough oxygen to complement the situation.

Muscles, Pathology and Epidemiology

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Muscle pain can be as a result of accidents, excessive exercise or infectionsThere a number of disease that affect the muscles; some causes pain while some go painless. There are cases when muscle pain are as a result of excessive exercise or other underlying disease. Common diseases of the muscles are muscle cramps, tendinities, myositis, myopathy etc. A very common pathology of muscles is tetanus.

Tetanus is an infection caused by bacterium clostridium tetani. This bacteria is found in the soil, manure and dust. It can gain entrance into the body through a breakage in the skin. Tetanus is characterized by muscle spams usually starting with the jaw. Tetanus however only affect smooth muscles and skeletal muscles and never cardiac muscles meaning the heart is not affected. Tetanus can lead to death if not treated, however even after treatment 10% of people who contract tetanus die. Tetanus vaccines are administered to create immunity against the bacterium.

Muscles and Exercise

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Exercising is a fundamental of healthy livingExercise is very good for the body; muscles are worked out, blood is pumpeed , there is increase in oxygen intake and also blood flow to the brain. Exercising is essential for burning fats, developing strength, improving posture etc. It is a fundamental part of healthy living. Other ways of caring for the muscle include maintaining you weight, stretching muscle, avoiding stimulants and cigarette, eating balanced diet and making use of them.

Further Reading:

• Muscular System
• Muscles
• List of skeletal muscles
• Somatic Nervous System
• Metabolism in Muscle
• Energy in Muscle
• Diseases of Muscle
• Tetanus

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Thanks for taking your time to read this post on Musocles, I'm sure you learnt a lot from this article.
Do leave a comment on what you think about muscles.

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