Fred and Mary were working in the library and were asked toshift textbooks from one shelf to another. Fred asked Mary to holdout her hands so he could stack several books on her arms to carrymultiple books at once. Fred noticed when he placed a textbook onMary’s arms they would extend downward slightly for a moment andthen return quickly to the original position, this happened witheach additional textbook he added. Mary was surprised by this asshe didn’t feel as if she was voluntarily restoring her armposition. When Fred placed a 5th very heavy textbook onto the stackin Mary’s arms her arms relaxed and all the text books fell to thefloor, Mary insisted she didn’t drop the books purposefully but didfeel the load was becoming too heavy for her to maintain her armposition.

1a) Which reflex is first being elicited as Fred adds each bookto Mary’s arms to enable Mary to maintain her arm position? Providea description of this neural reflex pathway, including thestimulus, receptor, neural pathway, effector and response. You mayuse a diagram if you wish.

1b) As Fred added the 5th textbook the increased load causedMary’s arms to relax. Which sensory receptor was activated here andwhat is this detecting in the muscle? How does this result in Marydropping the books?