- How are voluntary movements produced?
- Striated and smooth muscles
- Myosin and actin
- Automatic movements
- References
The voluntary movements are those that man does willingly, like taking something with your hands, talk, stand or lie in bed. The opposites are involuntary movements, such as heartbeat, blinking, or peristaltic movements.
All voluntary movements are made possible by the nervous system, an intricate network of neurotransmitters that send and receive electrical signals to or from the brain, where they are processed and transformed into action.
Breathing is one of the voluntary human movements
In the specific case of movement, it originates from the contraction of the muscles and the movement of the bones and joints that accompany them. With each movement, a group of muscles are put into action that allow the body to move.
The voluntary movements of the body are carried out basically at the level of the outer part of the body, that is, those carried out by the muscles that cover the skeleton, called skeletal muscles.
The rest of the internal activity of the body, such as the beating of the heart, the pumping of blood through veins and arteries, the processes of the different internal systems and organs (breathing, digesting, etc.) are not voluntary movements.
How are voluntary movements produced?
Voluntary movements are active because they are activated from the central nervous system (CNS). This system is made up of the brain, cerebellum, and spinal cord.
In the cortex of the brain reside nerve impulses - a tiny electrical discharge that lasts milliseconds and is measured in milli volts - that travel through the nerves and spinal cord to the skeletal muscle to produce movement.
As a result of this signal, proteins such as actin and myosin are alternately activated and overlapped, producing the excitation of a certain group of muscles and the relaxation or inhibition of the opposite group, thus allowing their length to change and the desired movement to be carried out..
This action is clearly visible when, for example, we try to bend an arm or a leg, or in the act of walking or going up and down a ladder.
As a muscle is stretched to flex the limb, its opposite has to shrink to complete the movement.
Voluntary muscle contractions are controlled by the brain, while reflexes and involuntary movements are controlled by the spinal cord.
Striated and smooth muscles
Most of the muscles susceptible to being moved by the will of the individual (skeletal) are striated muscles, named for the rough appearance they have when viewed under the microscope.
In contrast, the muscles that cover the internal organs, which perform movements not controlled by man, are smooth muscles, with the sole exception of the cardiac muscle, which is also striated, but constantly moves without the intervention of its wearer.
Myosin and actin
If the skeletal muscles are observed under the microscope, the change in appearance of the muscles can be clearly appreciated when they are in a state of relaxation and when they contract, mainly due to the greater or lesser overlap of the muscle fibers due to the action of myosin and actin.
In this change, actin completely overlaps myosin when the muscle is contracted and withdraws when it is distended.
This overlap occurs thanks to the action of mechanical, chemical and electrostatic forces in which substances such as calcium, sodium and potassium intervene.
Automatic movements
Most of the voluntary movements of our body are quite automated and we do them almost without realizing it.
However, these depend on our decision to do them or not. We decide to walk, scratch our noses or turn our heads from side to side as many times as we want, and we also decide when to stop doing those movements.
In either case, each movement previously required a highly complex process at the level of the cerebral cortex, which, due to its rapid and repetitive nature, is no longer highly elaborate.
The reason that they are movements that seem simple to us is because we have a lot of time repeating them in the same way; The experience and the information we get from the outside world, the practice in short, is what allows us to make these movements in a fluid and coordinated way.
To understand this process of learning and practice, it is enough to observe a baby learning to grasp objects with his hand, to walk or to speak. They are definitely not simple procedures at all and they take us quite a long time to master them expertly.
This mastery and control of body movements is achieved in two ways: visual representations, in which the individual repeats movements that they see in their environment, or through synaesthetic representations, that is, memorization by the repetition of previously performed movements, which leads, over time, to have better control of them.
The automation of movements then evolves gradually and in conjunction with motor habits, creating stereotypes and movements that, although they may be unconscious, do not cease to be produced by the clear will of the person who performs them.
These habits and stereotypes are what make all human beings walk in a similar way, chew in a similar way, gesture and do all kinds of daily activities in a very similar way without the geographical area, social stratum or race interfering in a decisive way.
References
- Baltazar Medina (1980). Theory of movement. University of Antioquia, Institute of Sports Sciences. Physical Education and Sport Magazine. Year 2, number 2.
- Voluntary Movement. Recovered from facmed.unam.mx.
- Muscle contraction. Recovered from es.wikipedia.org.
- Action of actin and myosin on muscle contraction. Recovered from masbiologia2bct.blogspot.com.ar.
- Voluntary movements. Recovered from medicinalwiki.com.
- The ability to move. Recovered from espasa.planetasaber.com.
- Voluntary muscles and involuntary muscles. Recovered from anatomy-body-human.blogspot.com.ar.
- Voluntary and involuntary. Recovered from academia.edu.
- Parts of the human body that respond to voluntary movements. Recovered fromcuídodelasalud.com.
- Luca Merini. Mechanism of muscle contraction. Recovered from youtube.com.