Anatomy Practice Exam

What components make up a reflex arc?

1. Sensory receptor, motor neuron, and effector

2. Sensory receptor, sensory neuron, motor neuron, and effector

3. Sensory neuron, motor neuron, and spinal cord

4. Sensory neuron, effector, and cortex

The correct answer is: Sensory receptor, sensory neuron, motor neuron, and effector

A reflex arc is a neural pathway that controls a reflex action. The primary components of a reflex arc include: 1. **Sensory Receptor**: This is the part that detects a stimulus, such as pain or heat. It converts the stimulus into an electrical signal. 2. **Sensory Neuron**: This neuron transmits the electrical signal from the sensory receptor to the central nervous system (CNS), specifically to the spinal cord in most reflexes. 3. **Motor Neuron**: Once the signal is integrated within the spinal cord, the appropriate motor neuron is activated to carry the response signal away from the CNS to the effector. 4. **Effector**: This is typically a muscle or gland that responds to the motor neuron’s signal, generating a response such as contraction of the muscle or secretion from the gland. Choice B accurately lists all four critical components of the reflex arc—sensory receptor, sensory neuron, motor neuron, and effector—demonstrating the full pathway from stimulus detection to response execution. This comprehensive view of the reflex arc is essential for understanding how reflex actions operate in the nervous system.