First step in a reflex arc?

Answer 1

A reflex arc involves the following components:

1. The receptor is the part of the neuron (usually a dendrite) that detects a stimulus.
2. The sensory neuron transmits the impulse to the spinal cord.
3. The integration center involves one synapse (monosynaptic reflex arc) or two or more synapses (polysynaptic reflex arc) in the gray matter of the spinal cord.
4. A motor neuron transmits a nerve impulse from the spinal cord to a peripheral region.
5. An effector is a muscle or gland that receives the impulse from the motor neuron. In somatic reflexes, the effector is skeletal muscle. In autonomic (visceral) reflexes, the effector is smooth or cardiac muscle, or a gland.

Answer 2

Detection by receptor