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Unconditional reflexes are reactions that occur without our will - their example is when we withdraw a limb from a hot vessel after we accidentally touch it. We simply come into the world with unconditional reflexes - we don't have to learn them. However, the question remains: in what mechanism unconditional reflexes take place?

Unconditional reflexesare the ones we are born with. In physiology, a reflex is a reaction to a stimulus (external or internal) that occurs with the participation of the central nervous system (i.e. the brain or spinal cord). Generally, there are two types of reflexes, which are conditioned reflexes and unconditional reflexes. The first of them are acquired during life, and in the case of unconditional reflexes, we simply bring them into the world.

Unconditional reflexes: mechanism of occurrence

The unconditional reflex takes place completely without our will. These reflexes are reactions that we are not even aware of - they occur without our awareness.

Unconditional reflexes could, in the simplest terms, be treated as automatic reactions of the body to various factors - but for this to happen, the reflex arcs must function properly.

The reflex arc consists of several elements, which are:

  • receptor
  • sensory neuron
  • nerve center (i.e. spinal cord or brain)
  • motor neuron
  • effector

The task of the receptor is to perceive a stimulus (e.g. pain). After the receptor receives this information, it is transmitted to the nervous center via a sensory neuron. The signal finally goes to the aforementioned nervous center (e.g. spinal cord), from where the motor neuron transmits relevant information to the effector (executive organ, e.g. a muscle fiber).

The simplest example of a reflex arc has been described above - because they can be monosynaptic (with only two neurons), and polysynaptic, where apart from the sensory and motor neurons, they also include intermediary neurons (interneurons) .

This is the principle of unconditional reflexes: the impulse received by the body quickly reaches the structures of the central nervous system andthe appropriate response of the organism to it is also generated.

All these reactions take place without the involvement of the cerebral cortex, therefore the unconditional reflex appears shortly after contact with a factor - considering that they are often designed to protect a person from various harmful factors, the speed of appearance unconditional reflexes is absolutely essential.

Unconditional reflexes: examples

Unconditional reflexes occur in many situations - an example is the one where we burn ourselves with something and then we automatically withdraw the burned part of the body, the same is with other factors that cause us pain - after all, we also automatically run away from them. However, there are definitely more unconditional reflexes - examples of them include:

  • tendon reflexes (such as the knee reflex or the Achilles tendon reflex, which can be observed by irritating the relevant areas with a neurological hammer - then the muscle groups automatically contract)
  • eye accommodation reflex (related to the automatic adaptation of the optical system of the eye to the objects viewed at the moment - it is thanks to this reflex that we are able to see sharp objects located close, and then objects located at a much greater distance)
  • pupil reflex (consisting in changes in the width of the pupil depending on the amount of light reaching the eyeball - the pupil narrows under intense lighting and expands under low light intensity)
  • gag reflex
  • drooling after food is in the mouth
  • cough reflex
  • vestibulo-ocular reflex (noticeable when the whole body rotates and consists in the fact that the eyeballs then move in the opposite direction)

Unconditional reflexes in newborns and infants

As already mentioned, unconditional reflexes are present in us from birth. However, just as some of them accompany us throughout our lives (as is the case, for example, with the knee reflex), others are present only up to a certain point in life and then disappear. We are talking about unconditional reflexes in newborns and infants. Such are, among others :

  • Moro reflex(embracing reflex): it occurs, for example, when a loud noise appears in the child's environment or the child is scared in some other way; it consists in automatically straightening the upper and lower limbs, and then bending the body into an arc and tilting the head back, after which the child clenches his fists and embraces his limbsupper your chest
  • grasping reflex : after the child's hand is irritated by an object, the baby's fingers are automatically clasped on it
  • automatic gait reflex(aka support and tread): when a child is held under the armpits and their feet touch the ground, they begin to move their lower limbs as if they were to to walk

The above unconditional reflexes in children, as mentioned earlier, begin to disappear with the passage of time. It happens, however, at different stages of life, and just as the grasping reflex is no longer visible in a 3-month-old baby, the Moro reflex can be observed even until the child is 5 months old.

Unconditional reflexes in newborns are quite important when assessing the overall he alth of a child - thanks to them it is possible to analyze whether the pace of development of the children's nervous system is correct.

About the authorBow. Tomasz NęckiA graduate of medicine at the Medical University of Poznań. An admirer of the Polish sea (most willingly strolling along its shores with headphones in his ears), cats and books. In working with patients, he focuses on always listening to them and spending as much time as they need.

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Category:

Neurology