A patient who takes aspirin for arthritis pain asks the nurse why it also causes gastrointestinal upset.
Which of these explanations is most accurate?

Choice A rationale

Exudate accumulation, which is fluid and cells leaking from blood vessels, certainly contributes to the swelling (tumor) associated with a sprained ankle and inflammation. However, the feeling of heat (calor) is primarily a direct result of vasodilation and the subsequent increase in the volume of warm blood flowing into the injured area, raising the local tissue temperature.

Choice B rationale

The cardinal sign of inflammation described as heat (calor) is a direct physiological consequence of arteriolar vasodilation at the site of injury. This increased vascular permeability and localized hyperemia results in a greater volume of warm, oxygenated blood entering the capillary beds of the sprained ankle, which raises the local skin and tissue temperature.

Choice C rationale

An infection is a potential cause of inflammation but is not the mechanism that explains the localized heat. The process of an infection would still trigger the inflammatory response, including vasodilation and increased blood flow, which is the direct cause of the elevated local temperature observed on palpation.

Choice D rationale

A thermal injury, such as a burn, is a type of injury that causes inflammation and heat, but a sprained ankle is a mechanical injury (ligament tear/stretch). In a sprain, the heat is a result of the body's inflammatory response to the tissue damage, not a direct application of external heat or thermal damage itself.

Choice A rationale

Hyperplasia is defined as an increase in the number of cells in a tissue or organ. For example, the proliferation of glandular cells in the female breast during pregnancy. This differs from the described change where one cell type (ciliated columnar) is replaced by a different, more resilient cell type (squamous), without necessarily increasing cell number.

Choice B rationale

Anaplasia describes the loss of cellular differentiation, a hallmark of malignancy where cells revert to a more primitive, undifferentiated state. The resulting cells exhibit marked pleomorphism (variation in size/shape) and high mitotic activity, which is a far more severe and characteristic change than the adaptive cell substitution seen in the lung's lining.

Choice C rationale

Dysplasia involves deranged cellular growth, resulting in cells that vary in size, shape, and organization, and often signifies a pre-cancerous condition. The change in the smoker's lung (columnar to squamous) is typically a protective response, called metaplasia, which may progress to dysplasia but is not dysplasia itself initially.

Choice D rationale

Metaplasia is an adaptive reversible change where one differentiated adult cell type (in this case, ciliated columnar epithelium) is replaced by another differentiated adult cell type (stratified squamous epithelium). This is a protective response to chronic irritation, such as cigarette smoke, as the squamous cells are more robust, though they sacrifice the important function of mucous clearance.