When one cracks a knuckle, the stretching of the capsule lowers the pressure inside the joint and creates a vacuum which is filled by the gas previously dissolved in the synovial fluid. This creates a âbubbleâ which then bursts producing the characteristic âpoppingâ or âcrackingâ sound.
DOCTORS: Click here for the Professional Version. Burns are injuries to tissue that result from heat, electricity, radiation, or chemicals. Burns cause varying degrees of pain, blisters, swelling, and skin loss. Deep, extensive burns can cause serious complications, such as shock and severe infections. Small, shallow burns may need only to be kept clean and to have an antibiotic cream applied.
You can get burned by heat and fire, radiation, sunlight, electricity or chemicals. There are three degrees of burns: Thin or superficial burns (also called first-degree burns) are red and painful. They swell a little. They turn white when you press on them. The skin over the burn may peel off in 1 or 2 days. Thicker burns, called superficial partial-thickness and deep partial-thickness burns (also called second-degree burns), have blisters and are painful. Full-thickness burns (also called third-degree burns) cause damage to all layers of the skin.