Reflexes and reactions
Why the cat always lands on paws? What forces us to blink? How it turns out, what we continue to breathe even during a dream? All these actions the automatic reactions which are not giving in to the conscious control, - reflexes operate.
Reflexes differ on complexity degree - from automatic otdergivanija hands from a hot surface to more difficult reflexes keeping position of a body at loss of balance. Since the birth we already possess a considerable quantity of primary reflexes (congenital) on which are gradually imposed set of the reactions got by us.
That such a reflex?
The Reflex is an automatic reaction on concrete razdrazhitel, not supervised by consciousness. For reflex occurrence presence of the sensitive nervous termination is necessary; nervous fibres for transfer of the message which bears razdrazhitel; body, reformative the information in reaction; and, at last, muscles and glands for realisation of the reaction - usually any mechanical movement.
Conscious reaction sometimes allows to overcome some reflexes - for example if we are reckless enough we can hold a hand on a hot plate, but it is necessary to make conscious effort it. Thus, reflexes provide to a body almost instant protective reactions, especially on danger signals. Few reflex actions, for example, breath, play so important role that even if they manage to be stopped for a while by means of conscious efforts, they renew sooner or later contrary to the consciousness control.
Types of reflexes
There is a set of various types of reflexes. Some supervise reductions of muscles, the basic functions of a body and orientation of movements. More difficult reflexes program our reactions to danger.
Muscular reflexes would be more correct to name "ёѕ§юцшыіэ№ьш Ёх¶ыхъёрьш" as vibrations of sinews serve as their reason. All reflexes make a part of the difficult mechanism (independent nervous system) in a spinal cord, supervising a tone of muscles, that is their readiness for action. Spinal cord actions, in turn, are supervised by a brain. So, spinal cord reflexes can become more active (supervised by sympathetic nervous system) or to be slowed down (supervised parasympathetic nervous system) agree "ѕё=рэютъх" received from above. The Same mechanism of a spinal cord is connected with receptors (sense organs) in a skin that provides fast reflex reactions at reception of dangerous stimulus.
If you have slipped on an ice path, the body itself is bent in the necessary direction, and you throw up hands to stop falling. It is a bright example of with what speed can work the reflexes supervising our position and orientation. Considered reactions are programmed by more difficult parts of our impellent system. The sensitive perceiving devices which are in ears, constantly supervise our position in space. When we fall, the messages sent by them, are quickly transferred in a cerebellum located at the basis of a brain which chooses necessary sequence of commands for muscles of hands and feet. The elementary examples such orientatsionnyh reflexes can be observed at kids. If, for example, suddenly to release a head of the baby, it extends hands, as though trying to grasp something. The given reflex is called as a reflex of Moro (by name for the first time the doctor who has described him) and, at normal development of the child, disappears already after several weeks of a life.
Reflexes of corporal functions
While the child in diapers, the conscious control over mocheispuskaniem at it is absent. When the bladder is full, thanks to pressure arising in it in a spinal cord signals about necessity to involve a reflex oporozhnenija arrive. Developing, the child gets ability to suppress this reflex till the moment, there will be no yet a possibility to be released from urine. But even adult people cannot do it infinitely: there comes the moment when the bladder under the influence of a reflex is released "ёрьюяЁюшчтюыіэю" (actually, by means of a spinal cord). Similar reflexes supervise many basic functions of an organism, including breath. Of them, for example, oporozhneniem a bladder and, to a lesser degree, breath, it is possible to operate some meaningly; others, such as heart reduction, are completely automatic.
These are the most difficult reflexes used for standard behavioural reactions of a body in extreme situations. The best example can so-called reaction "сюЁю=іё serves or to escape схуё=тюь" - model of the reflex reactions arising in reply to danger. Having met the street robber, we either are protected, or we escape; the same choice faces to an animal at the moment of an attack on it of a predator. Requirements of a body substantially same irrespective of, resistance decides our brain to run or remain and show. Accordingly, this difficult reflex automatically provides an optimum mode of warm reductions, breath, etc.
The Given group of reactions includes process of allocation of sweat (providing with that loss of heat by an organism during struggle or flight) and pallor of a skin (as the blood arriving earlier to a skin, goes to muscles). This reflex turns in due course in conditional and works at one only thoughts on a frightening or menacing situation.
The Reflex name conditional if it is caused by the stimulus which is distinct from initial (or from congenital). It occurs, when the second razdrazhitel repeatedly repeats together with natural stimulus.
The Given kind of a reflex has been described for the first time by the outstanding Russian physiologist Ivan Pavlovym who has noticed that if each time during feeding of a dog to call in a hand bell after a while at it the saliva in reply to a hand bell sound starts to be allocated - at first this reflex reaction was caused only by food. The described version of a conditioned reflex underlies many methods used for training of animals.
For what reflexes are necessary?
Without demanding conscious intervention, reflexes are the important part of our nervous system. Being very proof and more or less automatic, they save time and intellectual energy when it is required to make fast, and often saving action.
In medicine reflexes with success are used for research of various sites of nervous system that allows to localise illness. For example, suhozhilnyj the reflex is organised in a spinal cord on segments. The doctor investigates each of them by turns, yet will not allocate segments operating properly. It allows it to define, what part of a spinal cord is amazed by illness.
If reflexes are lost
Importance of reflexes in an everyday life of the person is various. In itself loss of a knee reflex a little that changes, though the reason which has caused its loss, can lead to occurrence of any other symptoms.
Occasionally people are born without some suhozhilnyh reflexes that does not prevent to live it a high-grade life. However there are vital reflexes, for example, orientatsionnyj a reflex. In its loss result some diseases of a cerebellum, and in this case it is very difficult to person to support balance without special intellectual concentration. In a similar way, at loss migatelnogo a reflex the motes which have got to it which could be removed blinking can easily harm an eye.
The People who have lost an automatic respiratory reflex, appear in very difficult situation at night when the conscious control of breath is absent. They require special supporting treatment for the period to a reflex complete recovery.