Which of the following hormones is controlled by positive feedback?Multiple Choiceprolactinoxytocingrowth hormoneantidiuretic hormonegonadotropic hormone

Step 1: Break Down the Problem

We need to identify which one of the given hormones is controlled by positive feedback. The options provided are:

1. Prolactin
2. Oxytocin
3. Growth hormone
4. Antidiuretic hormone (ADH)
5. Gonadotropic hormone

Step 2: Relevant Concepts

• Negative Feedback: Most hormones are regulated by negative feedback mechanisms, where the action of the hormone inhibits further secretion.
• Positive Feedback: In contrast, positive feedback mechanisms involve the amplification of a response, leading to increased secretion of a hormone in response to an initial action.

Step 3: Analysis and Detail

• Prolactin: Generally regulated by negative feedback involving dopamine.
• Oxytocin: Controlled by positive feedback during childbirth; its release increases in response to uterine contractions, which further stimulates additional contractions.
• Growth Hormone: Primarily controlled by growth hormone-releasing hormone (GHRH) and somatostatin (negative feedback).
• Antidiuretic Hormone (ADH): Generally regulated by negative feedback involving blood osmolarity and volume.
• Gonadotropic Hormone: Regulated by a complex feedback system involving the gonads but is not primarily positive feedback.

Step 4: Verify and Summarize

Among the hormones listed, oxytocin is most classically associated with a positive feedback loop during labor, where its levels rise as contractions occur, leading to more release of oxytocin.

Final Answer

Oxytocin is the hormone controlled by positive feedback.