OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

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What do electrical impulses in neurons mainly trigger?

Mechanical movement
The release of transmitter chemicals
Electrical resistance
Thermal energy

The correct answer is: The release of transmitter chemicals

The primary role of electrical impulses in neurons is to trigger the release of transmitter chemicals, which are essential for communication between nerve cells. When an electrical impulse, also known as an action potential, travels along the axon of a neuron and reaches the synaptic terminal, it causes voltage-gated calcium channels to open. This influx of calcium ions into the terminal prompts synaptic vesicles, which contain neurotransmitters, to fuse with the presynaptic membrane. The vesicles then release their contents into the synaptic cleft, allowing the neurotransmitters to bind to receptors on the postsynaptic neuron, thus transmitting the signal. This process is crucial for the functioning of the nervous system, as it facilitates communication between neurons and influences many bodily functions, including muscle contraction, perception of stimuli, and the regulation of mood and behavior. The other options, while they may involve electrical signals in some contexts, do not accurately represent the primary purpose of electrical impulses in the neural context.