9 Biology, Ms. Mayfield
1.3 The synapse: Overview
1. Name the three parts of a synapse:
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2. Explain why it is important for neurotransmitter-molecules to be deactivated soon after being released:
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3. Electrical impulses can only travel across a synapse in one direction. Explain.
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Task:
The picture below explains the message transport across a synapse. Number the steps! Find the right text for the gaps in the picture and fill in the corresponding number.
Step _____: An electrical nerve impulse (message) arrives at the end of the presynaptic axon, the axon terminal. The electrical impulse causes synaptic vesicles (bubbles) containing neurotransmitter- molecules to be released into the gap between the neurons (synaptic cleft).
Step _____: The neurotransmitter moves across the synaptic cleft to receptors on the postsynaptic membrane.
Step ______: The neurotransmitter binds to receptors on the postsynaptic membrane.
Step _____: After binding a
neurotransmitter-molecule the receptors on the postsynaptic membrane create a new electrical impulse that travels through the postsynaptic neuron.
Step ____: Enzymes located on the postsynaptic membrane deactivate the neurotransmitter molecules in the synaptic cleft.
