Caffeine in 1820 was discovered in coffee. Later in 1827 a substance called theine was discovered in tea. At that time caffeine and theine were considered different substances. A few years later in 1838 it was proven that caffeine and theine were identical substances.
Caffeine has a bitter taste and produces a recognizable physiological effect. A stimulant that occurs naturally in coffee beans, tea leaves, kola nuts and cocoa beans. It has been used in manufacture of cola beverages.
It is odorless, white, crystalline solid ,and slightly soluble. It increases blood pressure,stimulates the cerebral cortex, stimulates action of heart and lungs,and is a diuretic. It is an alkaloid found in coffee, tea, cacao.
The effects caffeine has on the body is a stimulant effect on all organs and tissues. Caffeine works on chemical reactions within individual cells. Caffeine causes the adrenal glands to release epinephrine (adrenaline) and norepinephrine (noradrenaline) hormones that stimulate cell activity.
In the brain cells are stimulated and drowsiness and fatigue are reduced. Reactions are speeded up and concentration is improved. Large amounts of stimulation cause anxiety, irritability and restlessness. This can cause insomnia, or a hangover effect with excessive fatigue and drowsiness in the mornings.
The heart is stimulated the blood circulates faster and blood pressure increases for a short period. To much stimulation could result in palpitations.
In the stomach small amounts of caffeine are actually good, for it helps in digestion. To much however causes abdominal pain and nausea.
In the skeletal muscles small amounts of caffeine improves the muscles performance in exercise. Because caffeine improves short term performance caffeine is banned in sports competitions.To much caffeine could cause the muscles to twitch.
In the Kidneys caffeine increases the production of urine.
Some people are particularly sensitive and suffer side effects from small amounts of caffeine. People who consume large amounts of caffeine find their system has adapted and their tolerance has increased therefore they must increase their amounts to feel any stimulant effect. If this person goes without caffeine for even a few hours they suffer withdrawal effects such as tiredness,irritability, and headaches. This is due to psychological and physical dependence on caffeine.
The medical use of caffeine includes the use for migraine, narcotic poisoning and shock. In medicine caffeine is mixed with certain analgesic. Caffeine has been used in analgesic to enhance their pain killing action. This is being reevaluated since recent studies may prove that it does not have this effect after all.