Edexcel iGCSE Biology-3.39 Role of Neurotransmitters at Synapses- Study Notes- New Syllabus

Role of Neurotransmitters at Synapses

🌱 Introduction

Neurons communicate with each other through synapses.
Synapse → small gap between the axon of one neuron and the dendrite of another (or effector cell).
Neurotransmitters are chemical messengers that cross this gap.

🧩 How Neurotransmitters Work

• Electrical impulse arrives at the end of the axon (presynaptic neuron).
• Vesicles release neurotransmitters into the synaptic cleft (gap).
• Neurotransmitters diffuse across the synapse.
• Bind to receptors on the next neuron (postsynaptic neuron) or effector.
• Trigger a new impulse in the postsynaptic neuron or cause the effector to respond (e.g., muscle contraction).
• Neurotransmitters are broken down or reabsorbed to stop the signal.

🔹 Key Points

• Synapses ensure one-way transmission of impulses.
• Allow amplification or modulation of signals.
• Enable coordination of complex responses.

📊 Example Table

📌 Quick Recap
Synapse = gap between neurons or neuron & effector.
Neurotransmitters carry the message across the synapse.
Ensures rapid, precise communication between neurons.
Examples: acetylcholine, dopamine.