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.
The deeper the burn and the larger the burned area, the more serious the burn is. 1  First-degree burns are burns of the first layer of skin. 2  There are two types of second-degree burns 3  : Superficial partial-thickness burns injure the first and second layers of skin. 4  Deep partial-thickness burns injure deeper skin layers.