Crossing the gap
"Crossing the gap" is a free, interactive Class 11 Biology simulation for NEET, built on the lesson "Transmission of impulses" in Neural Control and Coordination. Move the slider through the steps at a chemical synapse, reading the line under the picture each time. Then switch to an electrical synapse and compare the gap. Chemical synapse: impulse → vesicles fuse → neurotransmitter into the cleft → binds receptors → ion channels open → new potential. Electrical synapse: membranes nearly touching, current passes directly, always faster, rare in humans.
From the lesson Transmission of impulses in Neural Control and Coordination. Change the values and watch what happens.
The idea behind it
NCERT §18.3.2
- Impulses pass from neuron to neuron at junctions called synapses. Each synapse is built from two membranes, one of the pre-synaptic neuron and one of the post-synaptic neuron; a gap, the synaptic cleft, may or may not lie between them.
- There are two types of synapse: electrical and chemical.
- At an electrical synapse the two membranes lie very close together and current flows directly from one neuron into the next. Transmission is much like conduction along a single axon, and is always faster than at a chemical synapse. Our body has few electrical synapses.
- At a chemical synapse the membranes are separated by a fluid-filled synaptic cleft, and chemicals called neurotransmitters carry the signal across. The axon terminals contain vesicles filled with neurotransmitter.
- When an impulse arrives at the axon terminal, it makes the synaptic vesicles move to the membrane, fuse with it and release neurotransmitter into the cleft.
- The neurotransmitter binds specific receptors on the post-synaptic membrane. This opens ion channels; the ions that enter can set up a fresh potential in the next neuron.
- The new potential may be excitatory or inhibitory.
Questions
2 answers
- What does the "Crossing the gap" simulation show?
- Move the slider through the steps at a chemical synapse, reading the line under the picture each time. Then switch to an electrical synapse and compare the gap.
- Is this simulation free?
- Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Transmission of impulses" in Neural Control and Coordination (Class 11 Biology).
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