Typical changes in total body water in older people include:

A. Pain at the site of injury, such as a paper cut, is often due to the release of chemical mediators like prostaglandins, bradykinin, and histamines, which are part of the inflammatory response. These mediators increase blood flow and sensitivity in the affected area, contributing to pain. Exudate (fluid containing white blood cells and proteins) also forms at the site to aid in healing, and this can increase sensitivity.

B. Increased perfusion (blood flow) is part of the inflammatory response, but it is not the direct cause of pain. While increased blood flow helps deliver nutrients and immune cells to the site, it is the chemical mediators that cause pain.

C. Bacteria entering the wound could cause infection, but pain from a paper cut is typically related to the inflammatory response rather than infection. If infection were present, pain would usually be accompanied by other signs like redness, heat, and pus.

D. Vasoconstriction is the opposite of what happens at the site of an injury. Inflammation causes vasodilation, not vasoconstriction, to increase blood flow to the area.

A. A superficial partial thickness burn affects only the outermost layer of skin (epidermis) and causes redness and pain, but it doesn't usually cause blisters.

B. A full-thickness burn involves the destruction of all layers of the skin, including the epidermis, dermis, and sometimes underlying tissue. This type of burn typically causes a white or charred appearance and may not be painful due to nerve damage.

C. Dermal thickness burn is not a standard classification of burn depth. Burns are typically classified into superficial, partial-thickness, and full-thickness categories.

D. A deep partial-thickness burn involves damage to both the epidermis and dermis, causing redness, swelling, and blistering. This is the most likely classification for a sunburn with redness and blistering.