Differences between Voluntary and Involuntary Muscles – Voluntary vs Involuntary Muscles

What is Voluntary muscles?

• Voluntary muscles are muscles that are movable by at the discretion of a person . They are usually connected to the skeleton system.
• The muscles are connected to bones via the use of tendons. They are responsible for all types of vertebrates’ movements.
• Voluntary muscles comprise around 40 percent of the total body weight and tend to be long and located close to bones.
• Stripped muscles in the voluntary muscle are called striated since the muscles comprise long thin, multinucleated muscle fibers . They are crossed in regular patterns of white and lines of white and red which create the appearance of striated.
• Every muscle cell has a nucleus, with the nucleus remaining in the peripheral region within the cells.
• These muscle fibres covered by a specific cell membrane, called myolemma, also known as the sarcolemma.
• The sarcolemma is a thick layer of the voluntary muscles and connects the fibers of the muscles to each other as well as the connective tissues.
• Additionally, the muscles are composed of contractile units, the sarcomeres, which shrink, causing the muscles to relax and contract. Sarcomeres have myosin and actin proteins that together cause the contraction of muscle through sliding against one another.
• Each muscle fiber is connected to each other by connective tissue. They interact with each other via blood vessels and nerves.
• The muscle control is managed by a portion of the peripheral nerve system called”somatic nervous system.
• The nervous system that is somatic comprises of efferent and afferent nerves that transmit messages to the central nervous system (CNS) and those that relay data from CNS towards the voluntary muscles to enable their contraction.
• They aren’t myogenic, and they require an external stimulation from a nerve to cause contraction.
• These muscles use a significant amount of energy to support their relaxation and contraction. Therefore, they have many mitochondria to satisfy the energy demands.
• Voluntary muscles show rapid contraction and relaxation when compared to the muscles that are involuntary. But, they also fatigue quickly and require frequent intervals of rest.
• They are vital as they play a role with the movements of parts of the body and in the locomotion of the body.
• A few examples of voluntary muscles are the triceps and biceps and quadriceps, diaphragm and pectoral muscles, abdominals, hamstrings.

Examples of voluntary muscles

Diaphragm

The diaphragm is the primary respiratory muscle which aids breathing by enhancing and decreasing the size that the thoracic walls contain. This is the shape of a dome muscle that is located underneath the lungs as well as the heart. It is a barrier that separates the abdominal part and the chest. The diaphragm is a muscle that is voluntary which controls by the phrenic nervous system that connects the neck up to the diaphragm.

There are numerous openings in the diaphragm to allow for the movement of certain structures such as the esophageal artery for the vagus nerve as well as the aortic opening for the aorta as well as the opening to the inferior vena cava. In addition to respiratory function the diaphragm also is involved in other functions other than respiratory. The diaphragm is responsible for increasing abdominal pressure in order to aid in the elimination of vomit, urine and the feces. It also creates an esophagus-wide pressure in order to stop acid reflux. A spasmodic inhalation diaphragm movements produce the distinctive sound that is referred to as hiccupping.

Biceps

Bicep muscles are muscles that have two heads or two points of origin. The two for humans are the Bicep femoris and bicep brachii. The bicep is the muscle that is located on the front on the arm’s upper part. The tendons that connect it to the protrusion of the inner limb near to the head portion of the radius, which is one of two bones that make up the forearm. The biceps brachii bends the forearm towards the upper arm, and is therefore used in pulling and lifting motions.

A bicep’s size brachii’s size is believed to be a sign of the strength of your body. The bicep is an example of a muscle located behind the thighs. It is located at the rear of the isthmus, and the at the back of the femur. It is connected to the fibula’s head and the tibia. It plays a role in the motion of the thighs, as well as the it is involved in bending the leg when kneeling.

What is Involuntary muscles?

• Involuntary muscle are those muscles which aren’t managed by force or consciousness and are usually connected to organs that show constant and frequent contractions and relaxation.
• Involuntary muscles are also referred to as smooth muscles or non-striated muscle since there aren’t any strenuous lines when examined under a microscope.
• The muscles are found in the internal organs’ walls such as the stomach, intestine urinary bladder, blood capillaries.
• The individual muscle cells of smooth muscles are thin, long and spindle-shaped, with the nucleus located in the middle.
• The myolemma or the sarcolemma found as cells membranes of muscles that serves to connect the muscles to one another. The sarcolemma that is present in the body is thinner and is less concentrated.
• One of the most common examples of muscles that are involuntary includes the heart muscle, which is different both in function and structure from other muscles that are involuntary.
• The muscle of the cardiac is made up of individual cells of the heart known as cardiomyocytes, which are joined with intercalated discs. The muscle cells are surrounded by collagen fibers as well as other components that make up an extracellular matrix.
• The contraction of the cardiac muscle differs from the contraction of smooth and skeletal muscles. It is created by the muscles through electrical stimulation.
• This could trigger an expulsion of calcium-ion ions out of the cells into the sarcoplasm-reticulum. The rise of calcium ions causes the myofilaments to slide past each other, causing excitation-contraction.
• Myogenic muscle in the Cardiac Muscle is in which nerve impulses are created within the muscles.
• The majority of the muscle cells that make up the fibers of the muscles that are involuntary work as an entire unit, where relaxation and contraction happen together.
• The muscles that are involuntary can be controlled through the autonome nervous system that is part of the peripheral nervous system.
• The motor nerves of the autonomous nervous system consist of a type of neurotransmitter-filled bulges termed varicosities.
• Because gap junctions connect muscles in the involuntary muscle and nerve signals, they can be transmitted from one cell to the next through neurotransmitters.
• Relaxation and contraction of the involuntary muscles is gradual and happens frequently.
• This means that muscles don’t tire quickly and are able to work for a long time.
• They also have a lower energy requirements when as compared with voluntary muscles and therefore have less mitochondria.
• Involuntary muscles play a role in the movement of internal organs. They also assist in the movement of food and fluids in the digestive system.
• Examples of involuntary muscles include the cardiac muscle as well as smooth muscle that lines of the gut tracts and blood vessels respiratory tracts, urogenital tracts and more.

Examples of involuntary muscles

Cardiac muscle

The Cardiac Muscle is an involuntary striated muscular found on the heart’s wall and experiences relaxation and contraction regularly. The muscle of the cardiac is comprised of individual cells of the heart called cardiomyocytes that are joined with intercalated discs. The muscle cells are enclosed by collagen fibers as well as other components that make up an extracellular matrix. The cardiac muscle’s contraction differs from the contraction of smooth and skeletal muscles.

Cardiac muscle is myogenic in which nerve impulses are produced within the muscles. Action potentials are created by the muscles through electrical stimulation. This could trigger releases of calcium ions from cells into the sarcoplasm-reticulum. The rise of calcium ions causes the myofilaments to slide past each other, causing excitation-contraction. Cardiac muscles are encircled by sympathetic and vagal nerves which regulate the contractions of muscles’ fibers.

Smooth muscle

Smooth muscle is a nonstriated, involuntary muscle made up of single unit or unitary muscle as well as multiunit muscles. Smooth muscle forms the walls of many internal organs, such as the urinary tract, the intestinal tract tract, as well as blood vessels. The ciliary muscle in the eye also has a muscle which regulates the dilation of the eye and also controls its iris, which alters the form of the lens.

Single unit smooth muscles comprise muscles in which the relaxation and contraction of the whole muscle take place in a single unit. Multiunit muscles can relax and contract separately as separate units. Muscle fibers exist enclosed by nerve fibers that consist of vesicles referred to as varicosities, or boutons that transmit neurotransmitters.

Key Differences between Voluntary and Involuntary Muscles

1. The voluntary muscles are under conscious control, while involuntary muscles remain under conscious control.
2. Voluntary muscles are under the management of autonomic nerves. those that are not voluntary are controlled by the nervous system somatosensory.
3. Voluntary muscles are the skeletal muscles, which are connected to the skin and bone while involuntary muscles are the smooth muscle that lines organs as well as heart muscle.
4. Voluntary muscles don’t contract in a rhythmic pattern, however certain involuntary muscles contract during an ongoing rhythmic cycle.
5. Voluntary muscles have multinucleated cells while involuntary muscles have non-inucleated cells.
6. Voluntary muscles can be found in the outer edge of the cell and involuntary muscles can be found in the middle within the cells.
7. The cells of voluntary muscles are long, while involuntary muscle’s cells are smaller.
8. The cells of the voluntary muscles are Sarcomeres, while involuntary muscle cells don’t contain Sarcomeres.
9. Voluntary muscle cells are joined by Z discs, while the involuntary muscles cells are joined through the intercalated disc.
10. Voluntary muscles contain troponin however, a few muscles that are involuntary (cardiac) have troponin within their muscles.
11. Voluntary muscles tire quickly however involuntary muscles will not get tired easily.

Similarities Between Voluntary and Involuntary Muscles

• Involuntary and voluntary muscles comprise two in the tissue of muscles found in the body.
• Both involuntary and voluntary muscles are made up of muscles cells.
• Both involuntary and voluntary muscles are controlled of the nervous system

Voluntary vs Involuntary Muscles