This topic summary covers Knowledge Organiser within Reflex Arc for GCSE Biology. Topic 3: Reflex Arc It is section 13 of 14 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 13 of 14
Practice
15 questions
Recall
20 flashcards
Knowledge Organiser
Key Terms
- Reflex arc — receptor → sensory → relay → motor → effector
- Involuntary — automatic; no conscious control
- Relay neurone — in spinal cord; connects sensory to motor
- Synapse — gap between neurones; neurotransmitter crosses it
- Neurotransmitter — chemical that bridges the synapse
Must-Know Facts
- Reflex arc: receptor → sensory neurone → relay neurone (spinal cord) → motor neurone → effector
- Reflexes are faster than voluntary responses because the spinal cord (not brain) coordinates the response
- Reflexes are involuntary — they cannot be consciously suppressed
- Two synapses in a typical spinal reflex: sensory-relay and relay-motor junctions
- Synapses are directional — neurotransmitters released pre-synaptically, bind post-synaptically only
- Examples: withdrawal from pain, knee-jerk reflex, pupil constriction, blinking
- Reflex purpose: protect the body from damage before the brain can process the stimulus