Caffeine is a potent stimulator of the central nervous system and very popular; approximately 90 percent of people worldwide consume at least one of several different sources of caffeine, according to Brown University Health Education. The stimulating feeling that caffeine causes is a result of hormone secretion from the pituitary gland.
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The Pituitary Gland
The pituitary gland is a small, pea-sized gland found at the base of the skull that secretes a number of hormones, each of which provides important signals to various tissues throughout the body. The pituitary gland is essential for regulating heart rate, blood pressure, sleep cycle, sexual functioning and emotions. This gland is divided into two portions: anterior and posterior. The anterior pituitary releases several types of hormones, including one that targets the adrenal glands that sit atop the kidneys.
Caffeine and the Pituitary Gland
After you consume caffeine, brain neurons become very activated. The pituitary gland interprets this elevated neuron activity as an emergency signal similar to the reaction your brain has when you are very frightened. This signal is transmitted through the corticotropin-releasing hormone the hypothalamus secretes. In response to this emergency signal, the anterior pituitary releases adrenocorticotropic hormone, also called ACTH.
Effects on the Adrenal Glands
The ACTH produced as a result of caffeine-induced stimulation of the hypothalamus and the pituitary gland stimulates the adrenal glands to secrete various hormones. One of these hormones is epinephrine, also called adrenaline, which has several activating effects, such as alertness. Consuming too much caffeine can cause you to feel jittery, restless and even anxious. Another hormone the adrenal glands secrete is dopamine, responsible for the addictive nature of caffeine.
Caffeine is identical in nature, no matter the source; therefore, all caffeine sources have the same effect on the pituitary gland. The common sources of caffeine include coffee beans, tea leaves and chocolate. Coffee and espresso drinks have about 80 to 90 mg of caffeine per serving; black and green teas have about half the amount of caffeine at about 40 mg per serving; and dark chocolate has about 20 mg of caffeine in each serving.