Iris (Definition) The iris is a structure within the eye that helps reduce the amount of light that reaches the retina. The iris is known as the colored part of the eye, and can be blue, brown, or any color or combination of colors in between. The iris is the portion of the eye that responds to light stimulation. ...Read more.
Scientists also speculate that caffeine may provide a mood-boosting effect that helps ease pain. Regardless of the mechanism by which it works, the data does indicate that caffeine does indeed make pain medications more effective and help ease pain.
Explanation. Caffeine's effects on your heart rate occur indirectly, as a result of its effect on your nervous system. It has a chemical structure similar to adenosine, a chemical naturally found in the brain.affeine is also found in soda and tea as well as in some prescription and non-prescription medications, such as pain relievers and cold medications. Caffeine has a number of metabolic effects on the body and may increase the heart rate in some instances.