physical factors which increase the rate of respiration?

Answer 1

Heat or energy expenditure

Answer 2

Generally, respiration (whole body, as opposed to cellular respiration) is generally driven by carbon dioxide. Most animals have chemoreceptors in the body and the brain that measure the pH and the amount of carbon dioxide and oxygen in the blood. Because pH is directly affected by the amount of CO2 in the blood, and because the brain receptors are the most sensitive, and because neither O2 nor CO2 can diffuse into the brain, but H+ can, it is usually the build-up of CO2 (and the resultant decrease in pH) that causes increased respiratory drive.
Other factors, such as the temperature, the metabolic rate, and the stimulation of exercise and/or the sympathetic nervous system, can also have an effect.

Answer 3

use of energy, such as exercise, temperature

Answer 4

not sure exactly what you were looking for, but I was thinking of obesity, anxiety, etc.

Answer 5

exercise