Reflex arc
A fast, automatic response to a stimulus that does not need conscious thought.
Last updated
Analogy
A shortcut: the signal goes via the spinal cord, not the brain.
In practice
You pull your hand away from a hot pan before you feel the pain.
Practice
Flashcards
- What is the path of a reflex arc?Receptor, sensory neurone, spinal cord, motor neurone, effector.
Interview questions
- Describe the route of a reflex action.
- A receptor detects the stimulus
- A sensory neurone carries the signal to the spinal cord
- A relay neurone passes it on
- A motor neurone sends it to an effector that responds
Questions people ask
Why are reflexes faster than normal actions?
In a reflex, the signal travels from the sensory neurone to the spinal cord and straight out via a motor neurone, without going through the brain's decision-making. The shorter route saves time, which helps protect you from harm, such as when you touch something dangerously hot.
What is a synapse?
A synapse is the tiny gap between two nerve cells. The electrical signal cannot jump across, so the first nerve cell releases chemicals that cross the gap and trigger a new electrical signal in the next cell. This one-way chemical step is why signals travel in only one direction.