1. Potassium channels open, allowing potassium ions to move out.
2. Some sodium channels open in the dendrite.
3. All ion channels close and the Na+/K+ exchange pump starts working.
4. Sodium ions diffuse toward a node of Ranvier.
5. Lights hit the retina.
6. The threshold level is reached.
7. Many sodium channels open in the axon membrane, allowing sodium ions to move in.
List, in order, the events in visual perception that must occur for a person to see an object: