This definitions covers Key Definitions within Nervous System for GCSE Biology. Topic 2: Nervous System It is section 11 of 17 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
Topic position
Section 11 of 17
Practice
15 questions
Recall
20 flashcards
📖 Key Definitions
Central nervous system (CNS): The brain and spinal cord; the coordination centre that processes information from sensory neurones and sends instructions to motor neurones.
Sensory neurone: A nerve cell that carries electrical impulses from sensory receptors toward the CNS.
Relay neurone: A nerve cell found within the CNS that connects sensory neurones to motor neurones and processes information.
Motor neurone: A nerve cell that carries electrical impulses from the CNS to effectors (muscles or glands).
Synapse: The tiny gap between two neurones across which neurotransmitters diffuse to transmit a signal from one neurone to the next.
Neurotransmitter: A chemical released from the end of one neurone that diffuses across the synapse and binds to receptor proteins on the next neurone, triggering a new impulse.
Receptor: A specialised cell or cell ending that detects a specific stimulus (e.g. light, pressure, temperature) and converts it into an electrical impulse.
Effector: A muscle or gland that responds to instructions from the CNS, producing a movement or secretion.
Accommodation: The process by which the lens changes shape to focus light from near or distant objects onto the retina, controlled by the ciliary muscles and suspensory ligaments.
Reflex arc: The nerve pathway that carries an impulse from a receptor to an effector during a reflex action: receptor → sensory neurone → relay neurone (in spinal cord) → motor neurone → effector.