How Tea and Coffee act as a CNS Stimulant ? Actions and Mechanism



A cup of hot tea or coffee which kickoff the day for most of the people across the globe. It is common known beverages.

China and India are the lead producers of tea where as Brazil and Vietnam are the key producers of coffee.

In general, we take tea or coffee because it helps to reduce sleepness and make brain sharp so that we can work effectively. But ever wonder how they act as CNS stimulants and how it reduce drowsiness or sleepness ? If yes then here is how it works.

Constituents in Tea and Coffee

Generally, tea or coffee contains methylxanthines (a group of alkaloid) like caffeine, theophylline and theobromine.

Nuts of cocoa plants also contains caffeine, present in cola flavored drinks.

A cup of hot coffee contain about 100-200 mg of caffeine while a cup of hot tea contain approx 25-50 mg caffeine.

Caffeine and Theophylline

They both have very similar kind of CNS stimulant effect. Humans can experience reduction in fatigue, leading to sleeplessness, improvising the concentration power, reduce reaction time

They also relaxes smooth muscles, increases the heart rate, dilates bronchioles and blood vessels.

Theobromine

Theobromine generally act as a vasodilator. It also have diuretic effect so it increases the urine formation.

Mechanism

Caffeine inhibits the formation of phosphodiestrase. The role of phosphodiestrase is to breakdown cAMP (cyclic adenosine monophosphate). But due to inhibition of phosphodiestrase, the breakdown of cAMP get stop which leads to prompt the noradrenaline in the heart.

Caffeine also antagonize the effect of adenosine.

Effects of Adenosine

In CNS, adenosine generally exhibit the depressant action, reduce motor activity, induce sleep, depress respiration and reduce anxiety.

Due to increase in adenosine through out the day, it induces the sleep. But caffeine somewhat nullify its action.

Caffeine also produce the effect similar to β adenoceptor agonists which lead to increase the heart rate, vasodilation, bronchodilation, etc 

Conclusion

Coffee contains more amount of caffeine than tea so tea serve as a better option for those who have some heart related problems like blood pressure. Although both have their own benefits and disadvantages.

What do you prefer ? Share your thoughts in comments below.


  

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