Positive feedback has occurred when
A)an increase in blood sugar increases the secretion of a hormone that stores sugar as glycogen.
B)a decrease in blood sugar increases the secretion of a hormone that converts glycogen to glucose.
C)a nursing infant's sucking increases the secretion of a milk-releasing hormone in the mother.
D)an increase in calcium concentration increases the secretion of a hormone that stores calcium in bone.
E)a decrease in blood calcium increases the amount of the hormone that releases calcium from bone.

Question

Quizplus · Accepted Answer

Positive feedback occurs when a stimulus triggers a response that amplifies or reinforces the original stimulus. The nursing infant's sucking triggers the release of the hormone oxytocin in the mother, which causes the contraction of the mammary gland and the subsequent release of milk. The increase in milk release amplifies the original stimulus provided by the infant's sucking, resulting in a positive feedback loop. Choices A, B, D, and E describe negative feedback loops, in which a stimulus triggers a response that opposes or reverses the original stimulus.

Positive Feedback Has Occurred When