Ask Doctor Cory.

Dr. Cory:

How do our bodies work when we laugh?

Paige Vega Lake Isabella, California

Dear Paige:

When we laugh, the rib muscles, the abdominal wall muscles (surface muscles of the abdomen), and the diaphragm (the main muscle used for breathing, found just below the ribs) all move as we let out a long breath of air ending with a "ha" sound. The lungs then take in more oxygen as we breathe in deeply. Our heart rate increases, pumping blood and carrying oxygen to all the body cells. Endorphins, our natural pain killers, are released so that after laughing, we feel a sense of relaxation.

Not only does laughter help to reduce stress in our lives, but it exercises our bodies as well. Some people call it "internal jogging." Researchers have suggested that the average American needs to laugh fifteen times or more a day to be healthy.

Dr. Cory:

How does poison ivy get inside your skin?

Andrew Glass Rixyville, Virginia

Dear Andrew:

Poison ivy contains an oil called urushiol (u-ROO-she-ol). Whenever the stem, leaves, flowers, or roots are broken or crushed, the oil comes out. If you come in contact with the plant, you may get this oil on your skin. Unless you are extremely allergic to the oil, it usually causes a very itchy, blistering rash. The rash can begin anytime from six hours to six days later.

Smoke or fire from the burning plants can cause the oil to spread as well. This method can be particularly dangerous if you inhale the smoke, which can cause a reaction in your nose or throat.

Be on the lookout for this plant so that you can avoid it. When you are in areas where it grows, wear protective clothing such as long pants, shoes, socks, and a long-sleeved shirt.

If you think that you've had contact with such a plant, try to wash with soap and water within five minutes. This cleansing may remove enough of the sap to prevent the rash and to keep the sap from spreading to other parts of the body. Anything else that comes in contact with the plant should also be washed, such as clothing, shoes, toys or sports equipment, and gardening tools. Pets should be washed if they come in contact with the plant because sap on their fur can spread to you.

To protect against poison ivy oil, you can buy over-the-counter lotions that can be applied to your skin.

Sincerely,

Cory SerVaas, M.D.

Send your health questions to: "Ask Doctor Cory," U*S*Kids, P.O. Box 567, Indianapolis, IN 46206. Or, e-mail your questions to: [e-mail]

This column does not replace your doctor's advice.