Contraction
When a muscle contracts it tightens and shortens, creating movement. In skeletal muscles, this is voluntary, however in many other muscles of the body it is automatic, or involuntary.
Many organs, such as those in the digestive and urinary system, use contractions to facilitate movement of its contents. In some types of urinary incontinence, Kegel exercises are used to recondition the pelvic muscles to contract appropriately.
Contrast
The word contrast has many uses, but all are derived from the idea of showing differences between two things or ideas. For example, consider the phrase “… in contrast to …”
Many medical procedures use contrasts that show a difference between two types of tissue, illuminating the desired part of the body. These are viewed through X-ray technology. Contrasts are also called X-ray dyes and contrast media.
One type of contrast is the barium enema, with which a physician can X-ray the colon using a fluoroscope. This is a time-lapse test and shows actual movement of the bowel, allowing the physician to detect rectal abnormalities both structural and motile.
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