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Flashcards · Biology · The Nervous System

Synapses and Neurotransmitters

15 cards

  1. What is a synapse?

    The junction between two neurones, with a tiny gap between them.

  2. Can an electrical impulse cross a synaptic gap?

    No. The signal changes into a chemical one, a neurotransmitter, to cross the gap.

  3. What is a neurotransmitter?

    A chemical released by a neurone that carries the signal across the synapse.

  4. Where are neurotransmitters stored before they are released?

    In vesicles in the end of the first neurone.

  5. How does a neurotransmitter cross the synaptic gap?

    By diffusion.

  6. What do neurotransmitter molecules bind to?

    Receptor molecules on the membrane of the next neurone.

  7. What happens when the neurotransmitter binds to the receptor?

    A new electrical impulse starts in the next neurone.

  8. Why can impulses travel in one direction only across a synapse?

    Vesicles are only on one side and receptors only on the other.

  9. Why does the first neurone's ending contain lots of mitochondria?

    They release energy for making and releasing the neurotransmitter.

  10. What happens to a neurotransmitter after it has done its job?

    It is broken down or taken back up, which stops the signal.

  11. Why does a synapse slightly delay an impulse?

    Diffusion across the gap takes a short time.

  12. A motor neurone is 0.8 m long and an impulse takes 0.008 s to travel along it. What is its speed?

    \(0.8 \div 0.008 = 100\) m/s.

  13. Which neurotransmitter works at the synapse between a motor neurone and a muscle?

    Acetylcholine.

  14. Why must a receptor have a specific shape?

    Only the matching neurotransmitter can fit into it and trigger an impulse.

  15. What is the usual mistake when describing a synapse?

    Saying that the electrical impulse jumps across the gap. A chemical crosses it.