Tricky question

Question

Thermoregulation (endotherms):

	a) A decrease in core body temperature activates physiological and behavioral mechanisms to retain body heat.
	b) An increase in the set point above body temperature will produce vasoconstriction.
	c) If core body temperature increases, negative feedback will produce an increase in temperature set point.
	d) both a) and b) are correct, and c) is incorrect
	e) a), b) and c) are all correct

Answer 1

a) A decrease from your body's set point ( using you as an example of an endotherm) triggers reactions to increase body temp back up to match the set point (determined by your hypothalamus). Physiological reactions could include vasoconstriction, which constricts your vasculature in order to minimize heat loss, and shivering which is your muscles contracting to increase heat. Behavioral could be you putting on a jacket when you are feeling cold.

b) Increasing set point means setting the "thermostat" (your hypothalamus) to a higher temp, so your body will then try to increase its temp to meet that new set point. To do this, vasoconstriction can happen to retain heat. Dilating your vasculature encourages heat loss, so constriction helps retain heat.

c) Negative feedback is to negate or decrease the original stimulus. If core body increases, i.e. when you are working out, you need to cool it back down to meet the setpoint. You do this through negative feedback, i.e. with sweating, which lowers the body temp from the original temp (stimulus). Again the goal here is to lower it back to homeostasis levels (the set point of your hypothalamus). For c to be true, that is positive feedback where the body's response is to amplify or increase the original stimulus (hot body= stimulus, so response causes even hotter body/increased temp).