Which of the following is an example of feedforward mechanism?
Increase blood pressure during supine posture
Salivation on smelling food
Shivering on exposure to cold environment
None of the above
Ans. (c) Shivering on exposure to cold environmentRef: Ganongs Review of Medical Physiology 25th Ed; Page No- 249* Thermoreceptors are located within the body (central Thermoreceptors) as well as in the skin surface (peripheral thermoreceptor).* Thermoreceptors within body function as conventional feedback sensor. If the CORE body temperature drops back to 37degC set point.* In contrast, thermoreceptors in the skin function as feed-forward sensor. How? Decreases in environmental temperature are rapidly sensed by skin thermoreceptors, and compensatory thermoregulatory responses are initiated before there is any appreciable fall in CORE body temperature.* Other example of feed-forward system:# Increased Heart rate and respiratory rate even before the start of exercise due to psychic stimulation.# Some rapid movement of body parts occurs so rapidly that there is not enough time for feedback control (slow). Thus brain controls these movements by feed-forward system.Extra MileThermoreceptorsReceptorsNerve fibers typeDetectsCool receptorsAdSkin cooling (<25degC)Warm receptorsCSkin warming (>35degC)Heat nociceptorsAdHot temperature (>45degC)Cold nociceptorsCCold temperature (<5degC)
Nervous System