Samantha is about to hand Megan a notebook that contains her biological psychology notes. Which of the following correctly describes how Megan's muscles will react to the heavy notebook?
A) The weight of the notebook will cause Megan's arm muscles to contract. This information will be sensed by mechanoreceptors around her joints and sent to her spinal cord via Ib fibers. The Ib fibers will excite gamma motor neurons, which will cause her arm to contract further to adjust to the heavier weight of the book.
B) The weight of the notebook will cause Megan's arm muscles to stretch. This information will be sensed by her spindles and sent to her spinal cord by gamma motor neurons. The gamma motor neurons will inhibit the alpha motor neurons, causing her arm muscles to relax enough that she won't drop the book.
C) The weight of the notebook will cause Megan's arm muscles to contract. This information will be sensed by her Golgi tendon organs and sent to her spinal cord by Ib sensory fibers. The Ib sensory fibers will excite alpha motor neurons that will cause her arm muscles to stretch enough that she won't drop the book.
D) The weight of the notebook will cause Megan's arm muscles to stretch. This information will be sensed by her spindles and sent to her spinal cord by Ia sensory fibers. The Ia sensory fibers will excite alpha motor neurons that will cause her arm muscles to contract enough that she won't drop the book.

Question

Quizplus · Accepted Answer

The weight of the notebook will cause Megan's arm muscles to stretch, which is detected by muscle spindles. These spindles send signals through Ia sensory fibers to the spinal cord, where they excite alpha motor neurons. This excitation causes the muscles to contract, adjusting to the weight to prevent dropping the notebook.

Samantha Is About to Hand Megan a Notebook That Contains