Laughter is the most common yet mysterious expression of humans. Although the intensity and tone of laughter vary from person to person, as soon as you burst into laughter, your brain will quickly send signals to the muscles and glands throughout your body. The recently published American magazine *Reader's Digest* describes a series of reactions that occur in various organs after a good laugh.
Face: When you laugh, 15 facial muscles contract and deform to create your unique smile. Blood flow to the face increases, making your cheeks flush red and revealing an expression of joy.
Eyes: When laughter is intense, tear glands are stimulated, which is what we call "crying from happiness." Whether they are tears of sadness or joy, they both have a stress-relieving effect.
Mouth: Laughter naturally causes people to open their mouths wide. Studies show that after a good laugh, the content of immunoglobulins in saliva and "disease-fighting" T lymphocytes in the blood significantly increase. This indicates that laughter can...