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A frictional force tangential to the direction of a flowing fluid, the force of which is directly related to the fluid’s viscosity shear stress. In blood vessels, shear stress acts on endothelium and is the mechanical force responsible for the acute changes in luminal diameter.
Stress parallel to a given surface (e.g., a fault plane) that results from forces applied parallel to the surface or from remote forces transmitted through surrounding rock.
stress(stres) [Fr. estresse, narrowness]
Physiological stresses include agents that upset homeostasis, such as infection, injury, disease, internal organ pressures, or psychic strain.
In psychology, stresses include perceptions, emotions, anxieties, and interpersonal, social, or economic events that are considered threatening to one's physical health, personal safety, or well-being. Marital discord; conflicts with others; battle, torture, or abuse; bankruptcy; incarceration; health care crises; and self-doubt are all examples of conditions that increase psychic stresses. The response of an organism or material to stress is known as adaptation. See: adaptation; anxiety; fracture; homeostasis; Laplace, law of; relaxation response