Caffeine
Caffeine is an alkaloid found in tea leaves (up to 4%), coffee seeds (up to 2%), Cola nuts (up to 6%), cocoa beans (up to 4%). As you can see, this substance is widely distributed in nature. For medical purposes, however, caffeine is produced synthetically. From a medical point of view, caffeine is a classic psychomotor stimulant. It has the property to excite the nervous system, reduce the feeling of fatigue, increase mental activity, and banish sleep. However, it should be borne in mind, especially for athletes, that caffeine does not increase physical activity, but, on the contrary, reduces it.
The stimulating effect of caffeine is associated with its ability to block the receptors of epinephrine-the inhibitory mediator of the Central nervous system. Caffeine reduces the sensitivity of nerve cells to adrenaline and thus, indirectly, has an excitatory effect. Caffeine, however, can also have a direct stimulating effect. Like other methylxanthines, it blocks an enzyme (phosphodiesterase) that restricts the conduction (transmission) of nerve impulses to the cell. As a result, any excitatory signal begins to affect the nerve cells more strongly. If you overdo it with caffeine, you may develop a pronounced psychomotor agitation (excitement of the mental and active sphere).
At the dawn of our century, caffeine was used in large doses to provoke symptoms in mental patients. Simultaneously with the Central nervous system, caffeine excites the autonomic (innervating internal organs) system. Increases the frequency and strength of heart contractions, increases the secretion of gastric juice, increases sweating, increases body temperature, etc. Blood pressure does not change, because although caffeine stimulates the release of vasoconstrictors, it also stimulates the release of vasodilators. In addition, caffeine has a diuretic effect, which in turn does not allow the rise of blood pressure. After taking caffeine (caffeinated drinks), your health improves, you feel refreshed, and your muscle processes and motor sphere are activated. Comprehensive studies of the effect of caffeine on performance have shown that after a single dose of it increases concentration and muscle strength, manifested simultaneously. Along with this, there is a decrease in all types of endurance and increased oxygen consumption, and this has an adverse effect on the heart muscle. Heart vessels may not always provide adequate blood flow and oxygen supply to the heart. The tolerance of high temperatures worsens, but the tolerance of cold improves. This is caused by a sharp increase in the intensity of metabolism. Caffeine slightly reduces blood clotting, increases urination, activates the processes of tissue oxidation. This increases the breakdown of glycogen. Its reserves in the liver and in the muscles are reduced. The vessels of the brain, skeletal muscles, heart, and kidneys expand. Increasing the breakdown of glycogen leads to an increase in the blood sugar content. Caffeine also has the ability to destroy subcutaneous neutral fat and increase the content of fatty acids in the blood. An increase in blood sugar and fatty acids is one of the reasons for the appearance of a feeling of cheerfulness and a surge of energy. It is fatty acids, once in the blood, that cause increased heat transfer and an increase in body temperature.
Constant long-term intake of caffeine, which blocks inhibitory adenosine receptors, causes a response in the body - the formation of new adenosine receptors and the synthesis of more than the normal amount of adenosine. As a result of this adaptive adjustment of the Central nervous system, the stimulating effect of caffeine is reduced. Addiction develops, in which already large doses of caffeine are required to achieve the same stimulating effect. Sudden withdrawal of caffeine, taken for a long time, leads to the fact that adenosine replaces all the receptors. There is a strong inhibition in the Central nervous system. Appear lethargy, General depression, drowsiness, nervous depression. Chronic caffeine intake depletes the nervous system. There is a slowdown in thought processes, a weakening of willpower, and a lack of self-confidence.
The most common caffeine - containing plant is tea. Its culture is the most ancient. More than five thousand years ago, Chinese shepherds noticed that animals, after gnawing on some bushes, became unusually frisky and mobile. The Chinese began to use tea leaves as a medicine for excessive sleepiness and lethargy. The Chinese " cha " means a young leaf. Chinese monks prepared tea as a sleep-inducing drink during multi-day festivals and ceremonies.
Coffee beans have a much lower caffeine content than tea leaves. The stronger stimulating effect of the coffee drink is simply due to the large amount of coffee used to make the drink.
Cocoa beans contain very little caffeine. Cocoa drink and chocolate, which are made from cocoa beans, have almost no stimulating effect, but contain a large amount of fat.
Quite a lot of caffeine in Cola nuts. There are about 125 species of Kola shrubs in total. Cola nuts contain cocaine in addition to caffeine.
All caffeinated beverages remove vitamin B1 (thiamine) from the body. Therefore, when using them, it is necessary to include a sufficient amount of this vitamin in the diet. It is best to take vitamin B1 in the form of phosphatemia in which the thiamine molecule attached to a single phosphate residue.
Summing up the above, we can conclude that you can use caffeinated drinks, but only to the place and time.
