11. The level of a sex hormone, testosterone (T), is controlled by negative
feedback. Another hormone, gonadotropin-releasing hormone
(GnRH), is released by the hypothalamus of the brain, which triggers
the pituitary gland to release luteinizing hormone (LH). LH stimulates
the gonads to produce T. When there is too much T in the
bloodstream, it feeds back on the hypothalamus, causing it to produce
less GnRH. While this does not describe all the feedback loops
involved in regulating T, answer the following questions about this
particular feedback loop.
A. What is the stimulus in this system? Explain your answer.
B. What is the control center in this system? Explain your answer.
C. What is the pituitary considered in this system: stimulus, sensor,
control center, or effector? Explain your answer.
