With reference to the negative feedback system shown in the figure above, which of the following descriptions best describes the receptors (marked A in the figure)used to detect decreases in blood calcium concentrations?
A)Parathyroid gland cells detect lowered calcium levels.
B)Neurons in the hypothalamus detect lowered calcium levels.
C)Thyroid gland cells detect lowered calcium levels.
D)PTH genes detect lowered calcium levels.
E)Osteoclasts detect lowered calcium levels.

Question

With reference to the negative feedback system shown in the figure above, which of the following descriptions best describes the receptors (marked A in the figure)used to detect decreases in blood calcium concentrations? 
A)Parathyroid gland cells detect lowered calcium levels. 
B)Neurons in the hypothalamus detect lowered calcium levels. 
C)Thyroid gland cells detect lowered calcium levels. 
D)PTH genes detect lowered calcium levels. 
E)Osteoclasts detect lowered calcium levels.

Quizplus · Accepted Answer

The parathyroid gland cells are responsible for detecting decreases in blood calcium concentrations and initiating the release of parathyroid hormone (PTH) to bring calcium levels back to normal. The other options are not involved in this specific feedback system.

With Reference to the Negative Feedback System Shown in the Figure