Which concept describes when the body adapts to exposures over time and begins to show less response to the same dose?

• A. Tolerance and sensitivity
• B. Exposure Routes
• C. Chemical Hazards
• D. Corrosive

Answer: (A)

When the body adapts to repeated exposure, the same dose produces a smaller effect because the system becomes less responsive. This is tolerance. It can arise from metabolic tolerance, where more of the chemical is broken down before it reaches target sites, or pharmacodynamic tolerance, where target cells become less sensitive (receptors downregulate or signaling diminishes). Tachyphylaxis is a term often used for a particularly rapid development of this reduced response after several exposures. The important idea is that the dose still enters the body and can be hazardous, but the observable effect is diminished, which can lead to using higher amounts to achieve the same effect. The other options describe exposure pathways, general hazards, or a chemical property, not the body’s adaptive response to repeated exposure.