The synapse
| English | Chinese | Pinyin |
|---|---|---|
| synapse | 突触 | tū chù |
| cholinergic | 胆碱能 | dǎn jiǎn néng |
| neurotransmitter | 神经递质 | shén jīng dì zhì |
| acetylcholine | 乙酰胆碱 | yǐ xiān dǎn jiǎn |
| neuromuscular junction | 神经肌肉接头 | shén jīng jī ròu jiē tóu |
| summation | 总和 | zǒng hé |
The gap between neurones
- A synapse 突触 is a tiny gap between two neurones.
- The electrical impulse can't jump the gap — so it's carried across by a chemical.
- The same idea connects a neurone to a muscle.
Neurotransmitters carry the signal across the synaptic gap from one neurone to the next.
They diffuse across the cleft because the electrical impulse cannot jump the gap directly.
The tiny gap between two neurones at a synapse is the synaptic ______.
The neurotransmitter diffuses across the synaptic cleft to the next neurone.
A cholinergic 胆碱能 synapse
- the impulse arrives and makes calcium ions enter the first neurone.
- this makes vesicles release a neurotransmitter 神经递质, acetylcholine 乙酰胆碱, into the gap.
- acetylcholine diffuses across and binds receptors on the next neurone.
- this starts a new impulse in the next neurone.
A cholinergic synapse passing a signal across the cleft
Across a synapse
Step through it. The electrical impulse becomes a chemical one — neurotransmitter carries the signal across the gap.
When an impulse arrives at a synapse, the first thing that happens is:
Ca²⁺ entering the presynaptic neurone causes vesicles to release acetylcholine into the cleft.
Acetylcholine carries the signal across the synapse by:
The neurotransmitter diffuses across the cleft and binds receptors, starting a new impulse.
Put the events at a cholinergic synapse in order.
Impulse → Ca²⁺ in → ACh released → ACh binds receptors → new impulse.
Match each part of the synapse to its role.
Ca²⁺ triggers release, ACh crosses and binds receptors, then the enzyme clears it so signals stay separate.
The neuromuscular junction 神经肌肉接头
- A neuromuscular junction works just like a synapse.
- But it is between a motor neurone and a muscle.
- The neurotransmitter triggers the muscle to contract.
A neuromuscular junction is a synapse between:
It works like any synapse, but the second cell is a muscle that is made to contract.
Why synapses matter
- Synapses make transmission one-way (only the ending releases neurotransmitter).
- They also allow summation 总和 and integration — many signals combining to decide the response.
You've got it
- a synapse is a gap between neurones; the signal crosses it as a chemical
- cholinergic synapse: impulse → Ca²⁺ in → vesicles release acetylcholine → binds receptors → new impulse
- a neuromuscular junction is a synapse between a motor neurone and a muscle