Question

In the knee jerk reflex, the effector and receptor are respectively,

• A. muscle spindle and motor endplate
• B. afferent and efferent neuron
• C. motor endplate and muscle spindle
• D. sensory and motor neuron

Answer 1

The correct option is C motor endplate and muscle spindle

Reflex action is the process of producing an involuntary response to an external peripheral stimulus, without putting in any conscious effort. A part of the central nervous system (spinal cord) is also involved in this process. The stimulus received and the response produced, along with the other components involved, results in the formation of a reflex arc.

There are various components involved in the reflex pathway. When the stimulus is received by the muscle spindle which acts as the receptor, the signal is transmitted to the dorsal nerve root through the afferent pathway and then to the central nervous system (spinal cord). From the central nervous system, the motor neuron transmits the impulse through the efferent pathway to the effector or the excitor, which is the motor endplate. Hence, the signal is perceived and the response is generated.

Therefore, in the knee jerk reflex, the effector and the receptor are motor endplate and muscle spindle, respectively.