In the knee jerk reflex shown in the figure, which of the following components of the reflex arc serves as the effector?
A)muscle spindle
B)gray matter of spinal cord
C)sensory neuron
D)motor neuron
E)quadriceps femoris muscle

Question

In the knee jerk reflex shown in the figure, which of the following components of the reflex arc serves as the effector? 
A)muscle spindle 
B)gray matter of spinal cord 
C)sensory neuron 
D)motor neuron 
E)quadriceps femoris muscle

Quizplus · Accepted Answer

The quadriceps femoris muscle is the effector in the knee jerk reflex, as it is the muscle that contracts in response to the stimulus. The other components of the reflex arc are: sensory neuron (A), which detects the stretch in the muscle spindle and sends a signal to the spinal cord; gray matter of spinal cord (B), which receives and integrates the signal from the sensory neuron; and motor neuron (D), which sends a signal to the quadriceps femoris muscle to contract.

In the Knee Jerk Reflex Shown in the Figure, Which