CAFFEINE

 


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History of Coffee

Kaffe Kantate

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Caffeine's activity comes from its resemblance to adenosine and cAMP

caffeine works in two ways :
it blocks the Enzyme phosphodiesterase from removing the secondary messenger cAMP, so the excitory signals from adrenaline etc. persist much longer (recall that viagra works in a similar manner)
and
it blocks Adenosine receptors in the brain. Adenosine builds up in the course of a day, and when levels are high enough, the adenosine binds to receptors that cause nerves to release inhibitory signals that lead to drowsyness and sleep. Adenosine also causes a dilation of blood vessels to the brain , presumably to provide more oxygen and nutrients to cells needing to be replenished.
 

adenosine
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protein ribbons
reset

So, the effect of caffeine is to disable braking systems in the brain (adenosine) and the body (phosphodiesterase) resulting in a prolonged sense of wakefulness and alertness. Among the physiological effects is a constriction of blood vessels which can relieve the pressure of migraines and other headaches. Caffeine can significantly increase the effectiveness of analgesics such as aspirin and is often included with them.

Tolerance

Withdrawal

 

 
However there can be a rebound effect when the caffeine has worn off (been metabolised) and you can end up with a worse headache. Headaches are also a common sympton of caffeine withdrawal for the same reason.
 
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