Difference between Voluntary and Involuntary Muscles

Locomotion and movement are the essential features of all organisms, whether they are unicellular or multicellular. For this action, there is a specific type of tissues known as muscular tissue. The cells of muscular tissue are called muscular cells. The muscular tissues are formed from the embryonic mesoderm. All muscular tissues and cells work accordingly to support the movement of the body and all parts. The primary function of the muscular tissues is to provide movement to the body but it also maintains the body posture and circulation of blood in the vascular system.

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The muscular system of the human body includes more than 700 muscles and comprises 40 per cent of the total body’s weight. These muscles are attached to bones, blood vessels and internal organs of the body. Muscles are of different types based on the structure and movement. Skeletal muscles, smooth muscles and cardiac muscles are three main types which are further classified into two main classes on the basis of their control; mechanism; voluntary muscles and involuntary muscles.

Voluntary muscles which are also known as striated muscles are those who work according to the one’s desire whereas involuntary muscle which is also known as white or smooth muscles are those who are not under one’s control. Examples of voluntary muscles are bicep muscle, alimentary muscle and urogenital tract whereas examples of involuntary muscles are abdominal muscle, locomotors muscle, middle ear muscle and diaphragm.

Comparison Chart

Basis for ComparisonVoluntary musclesInvoluntary muscles
DefinitionVoluntary muscle is the type of tissue which is under the control of the will and attached to the skeletal.Involuntary muscle is the type of muscles that contract without conscious control and found in the walls of internal organs.
ShapeSkeletal, stripedPlain and unstriped
Another nameStriated muscleWhite or smooth muscle
Nucleus numberMultinucleatedUninucleated
Nucleus locationPeripherally locatedCentrally located
Type of cellsLong cellsShort cells
SarcolemmaThickThin
DiscsZ discsSome with intercalated discs
Presence of troponinPresentIn a few muscles
Controlled byCentral nervous system (CNS)Autonomous nervous system (ANS)
ContractionsRapid and powerful contractionsSlow and rhythmic contractions
EnergyNeeds high energyNeeds low energy
FatigueGet fatigued easilyGet fatigued slowly
ExamplesSkeletal musclesSmooth muscles, Cardiac muscles
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What is a voluntary muscle?

Voluntary muscle form almost 40 per cent of the body’s weight. These muscles are under the control of the peripheral and central nervous system. Voluntary muscles are also known as striated or skeletal or striped muscles. These are formed of bundles of muscle fibres in the human body. Voluntary muscles’ bundles are long and present near the bones. These are unbranched and cylindrical and range between 1 mm to 30 cm.

The bundles of muscle fibres are bounded by the sarcolemma which has sarcoplasm and sarcoplasmic reticulum. Sarcolemma has two layers; plasma membrane and basement membrane. It is a transparent membrane and surrounds the muscle fibres. Sarcoplasm resembles the cytoplasm of the cell and present in the muscle fibre known as sarcoplasm. Syncytial is the nuclei present below the sarcolemma and has an oval or flat shape. There are many other organelles are present such as enzymes, fat drops, mitochondria, endoplasmic reticulum and Golgi apparatus. There are many parallel expanded threads like rods are present in the sarcoplasm of muscle fibres which are known as myofibril or sarcostyles. These myofibrils help in the contraction and relaxation of the muscle.

The entire muscle is covered by the epimysium, which is kind of connective tissue. Each end of the muscles is attached with the bones through tendons. There are dark and light bands present between each running fibre called myofibrils.

What is involuntary muscle?

Involuntary muscles are also known as unstriated or unstriped muscles. These muscles are under the control of one’s own desire. These are present in the walls of the internal organs such as urinary bladder, uterus, stomach, alimentary canal etc. because of this reason also called visceral muscles.

The cells of the involuntary muscles are long, thin and spindle shape but structurally very simple. There is an oval nucleus present in the centre of each cell. The nucleus is surrounded by the sarcoplasm. These are long, thin, parallel filaments present in the sarcoplasm is called myofibrils. These muscles do not exhibit dark and light bands, although action and myosin are present.

The primary function of the involuntary muscles is to help in movement but these muscles also enable the body to keep posture and body position, stabilize joints as well as produce heat to maintain average body temperature. Some diseases that affect the involuntary muscles include occlusion of the coronary arteries caused by atherosclerosis or thrombosis.

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Key Differences between Voluntary and Involuntary Muscles

  1. Voluntary muscles are under conscious control, whereas involuntary muscles are under unconscious control.
  2. Voluntary muscles are in the control of the autonomic nervous system whereas involuntary muscles are under the power of the somatosensory nervous system.
  3. Voluntary muscles include skeletal muscles that are attached to the bone and skin, whereas involuntary muscles include smooth muscles that line organs and cardiac muscles of the heart.
  4. Voluntary muscles do not contract in rhythmic cycle whereas some involuntary muscles contract in a continuous rhythmic period.
  5. Voluntary muscles contain multinucleated cells, whereas involuntary muscles contain uninucleated cells.
  6. Voluntary muscles are located on the edges of the cell, whereas involuntary muscles are located in the centre of the cell.
  7. Voluntary muscle’s cells are very long, whereas involuntary muscle’ cells are small.
  8. Voluntary muscles’ cells have sarcomeres, whereas involuntary muscles cells do not have sarcomeres.
  9. Voluntary muscles cells join at a Z disc, whereas involuntary muscles cells are joined by an intercalated disc.
  10. Voluntary muscles have troponin, whereas a few involuntary muscles (cardiac) have troponin in them.
  11. Voluntary muscles tire easily, whereas involuntary muscles do not tire out easily.

Conclusion

In conclusion, voluntary and involuntary muscles are the type of muscles based on their movement. Movement of voluntary muscles is under the man’s conscious, whereas involuntary muscles do the movement with their own will.

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