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.
Effects on the Body: Hormones- You can feel the effects of caffeine in your system within a few minutes of ingesting it, and it stays on your system for many hoursâit has a half-life of four to six hours in your body. While in your body, caffeine affects the following hormones: