For each degree Fahrenheit rise of body temperature, the pulse rate will increase about

• A. 2 beats
• B. 4 beats
• C. 6 beats
• D. 10 beats

Answer: (D)

When body temperature climbs, the body's metabolic rate increases, so tissues need more oxygen and produce more heat and CO2. The heart responds by pumping more blood to meet these demands and help circulate heat away. A handy clinical rule is that the pulse rises by about 10 beats per minute for each 1°F increase in temperature. This makes tachycardia a common companion of fever and gives clinicians a quick way to anticipate how much the heart rate might rise with fever. Remember, this is an approximate guideline— individual factors such as age, medications, hydration, and overall health can shift the exact change.