WE REMOVE HAND when we touch the hot kettle, close our eyes when the ball is flying directly at us, and try to turn as conveniently as possible when falling. These reactions are controlled very quickly, at the level of the spinal cord, and are called reflexes. True, the cerebral cortex can also be connected in the process – for example, if you fall with your beloved mother’s favorite cup in your hands, the brain will have to weigh the pros and cons before making a final decision. Basically, reflexes are designed to protect us from real and potential threats, although the function of some of them is difficult to understand. Let’s try to figure it out with everyone.
Unconditional and conditional
Simplified to the maximum, a reflex is a quick reaction of the nervous system to a stimulus that is outside of our control. We are born with most of them – these are, as they said at school in biology, unconditioned reflexes. But there are also conditioned reflexes – those that we acquire by necessity during life. One of the first researchers of conditioned reflexes was the Russian physiologist and winner of the 1904 Nobel Prize, Ivan Pavlov. His legendary experiment, in case you forgot, was to induce gastric acid production in a dog with a stimulus that had nothing to do with digestion: sound or light.
Reflex research continues and leads to unexpected discoveries. Vertebrates have a so-called vestibulo-ocular reflex – it allows you to focus on one point when the head moves. It has long been thought to be controlled by the brain stem, but scientists at King’s College London have shown that higher-order brain regions are involved in its control, among other things, for hand movements. So primitive reflexes may not be so primitive.
Autonomous and infant
After brain death, some patients may move their limbs . And this confuses the relatives – after all, if the main organ is dead, then nothing like this should happen, right? Not really. In this case, we are talking just about the spinal reflexes, which can occur within 24 hours after the death of the brain, including a sequence of movements known as the ” Lazarus phenomenon “.
Most of the reflexes are autonomous and work within the body. For example, spikes in blood pressure in response to stress or digestion in response to food entering the stomach. Babies have a number of reflexes that are not found in adults: palmar, sucking, searching and some others .
We used to think of coughing as something not very positive, but in general, the cough reflex is what helps us stay healthy, because it removes pathogenic particles from the airways. In short, if the cough does not cause pain and discomfort, and the doctor has not given other recommendations, you should not suppress this reflex. If a person chokes and coughs, there is no need to pound on the back – no external influence is as powerful as a cough.
Cough is a protective reflex that is triggered when foreign particles enter the larynx, pharynx, bronchi; sneezing occurs if particles of dust, mucus or pollen are caught in the nose. The principle is the same – a fast air flow cleans the nasal cavity from unnecessary components. Finally, eyes watery from dust, wind, or makeup is also a simple example of a protective reflex.
Why do doctors knock
on the knee
Exposure to a stimulus, in this case a hammer, causes the thigh muscle to stretch slightly. Sensory (sensory) nerves in the muscle send a signal to the spinal cord; a response signal travels along the motor nerve, causing the muscle to contract. In this case, the knee is slightly unbend.
This simple reaction, the so-called monosynaptic (that is, working through one nerve synapse) reflex, helps the doctor to understand a lot about the state of the nervous system. Given the simplicity and speed of execution, it should come as no surprise that tapping with a hammer has become part of the routine inspection.
Reflexes can be pumped
Although reflexes seem to be something constant and unchanging, they can be improved. For example, one study found that relaxation (in this case, meditation practice) improves the speed of response tasks, while tension, on the contrary, complicates the process. The reaction speed is also practiced in various sports – for example, in boxing.
Potential helpers are eggs and spinach, which contain tyrosine, an amino acid that may also be associated with improved responsiveness. Researchers at the University of Rochester have generally found that action-packed video games can help people make faster, but better decisions. And while it sounds too good, you can try.
Why does one want to go to the toilet at the sound of water
The situation everyone was in: you tell your friends that you urgently need to go to the toilet, and at this moment the main joker in the company starts to turn on the sounds of streams and waterfalls on the phone, although you have not even seen the coveted door yet. And this is really terrible, because the urge to go to the toilet starts to get even more.
While science has no definitive answer to the question of why this is happening, it has speculations. One of the most viable among them says that, learning to relieve ourselves, first sitting on the potty and then on the toilet, we are accustomed to the fact that this action is accompanied by characteristic sounds (not only urine itself, but also flushing water and even washing hands).
This is a kind of conditioned reflex, which eventually became so firmly entrenched in our consciousness that some people may want to use the toilet even when they are just looking at the water (although this is not certain).
Knismesis, Gargalesis and others
The story with water is a textbook example, but, of course, strange reflexes are not limited to it. There are, for example, tremors or cramping after urination , which are more common in men than in women, and although scientists do not know exactly what causes them, this may be due to the loss of some warm fluid simultaneously with the exposure of a part of the body or a natural decline. pressure after the procedure. Sometimes people faint after urinating (according to some sources , this is 8% of fainting), but this has nothing to do with reflexes.
Another reflex, known as a “prisoner’s movie” , is observed in people who spend a lot of time in complete darkness (astronauts, meditation practices ). We are talking about flashes of light (and color) that scientists think occur when phosphenes (spots and stars that we see when we close our eyes) combine with a tense psychological environment.
There is also knismesis and gargalesis – two types of tickling that psychologists J. Stanley Hall and Arthur Allin identified back in 1897. Knismesis is a mild type of tickling that is accompanied by an itchy sensation (such as from a feather or a fly), but not laughter. Gargalesis is an active tickling, accompanied by laughter, but capable of being painful if the person who performs the action does not want to stop. Interestingly, we ourselves can cause knismesis, but never gargalesis.
Other surprising reflexes are flushing from shame , over-excitement, or emotional stress (emphasize as needed) associated with an overactive sympathetic nervous system; goosebumps provoked by cold or, again, emotions – here, most likely, there is a “program error”, since the same communication channels are activated as when reporting a low temperature. As for the reasons for yawning, science continues to argue – whether it is a lack of oxygen or the need to maintain an optimal brain temperature, scientists have not yet decided. The latter is more likely because people tend to yawn when the height changes.
Finally, most mammals have an unusual diving reflex that allows them to stay underwater longer. It works only in water with a temperature below 21 degrees Celsius and only when the face is immersed in it. If this happens, the heart rate slows down and the blood concentrates in the limbs, greatly increasing the chances of survival.
Japanese scientists suggest that it is human reflexes that will help create unique defense systems in the future. Because even biometric data can be copied, although it is difficult, but copying saccades (micromovements of the eyes while looking at something) and other reflexive things is much more difficult. Perhaps one day our strange reflexes will play an important role in shaping the new cybersecurity.