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6.3 Synaptic Transmission — Test 1
Q1. Saltatory conduction occurs in:✓ Myelinated nerve fibres
Q2. At a chemical synapse, the arrival of an impulse triggers neurotransmitter release by causing:✓ Calcium influx into the presynaptic terminal
Q3. An excitatory postsynaptic potential (EPSP) is produced by:✓ Depolarisation of the postsynaptic membrane (e.g. Na⁺ influx)
Q4. An inhibitory postsynaptic potential (IPSP) makes the postsynaptic neuron:✓ Less likely to fire (hyperpolarised)
Q5. Spatial summation at a neuron refers to:✓ Adding inputs from several synapses arriving together
Q6. Temporal summation occurs when:✓ A single synapse fires rapidly, so its potentials add up
Q7. An ionotropic receptor differs from a metabotropic receptor in that the ionotropic receptor:✓ Is itself an ion channel that opens directly
Q8. After acting on the postsynaptic receptors, neurotransmitter is removed from the synaptic cleft by all of these EXCEPT:✓ Synthesis of new transmitter in the cleft
Q9. The neurotransmitter acetylcholine is broken down in the synaptic cleft by:✓ Acetylcholinesterase
Q10. Electrical synapses differ from chemical synapses in that they:✓ Use gap junctions for direct, very fast transmission
Q11. Axonal transport carries materials such as vesicles and proteins:✓ Both away from and toward the cell body along microtubules
Q12. The synaptic delay at a chemical synapse is due mainly to:✓ The time for transmitter release and diffusion across the cleft
Q13. A neurotransmitter that opens chloride channels and produces inhibition is:✓ GABA
Q14. The chief excitatory neurotransmitter in the mammalian central nervous system is:✓ Glutamate
Q15. In a chemical synapse, neurotransmitter is stored in the presynaptic terminal within:✓ Synaptic vesicles
6.3 Synaptic Transmission — Test 2
Q16. Conduction velocity is fastest in nerve fibres that are:✓ Large in diameter and heavily myelinated
Q17. At an excitatory synapse using acetylcholine on skeletal muscle, the receptor involved is the:✓ Nicotinic acetylcholine receptor (ionotropic)
Q18. The neuromuscular junction is a special type of:✓ Chemical synapse between a motor neuron and a muscle fibre
Q19. Continuous conduction (along an unmyelinated axon) is slower than saltatory conduction because:✓ The whole membrane must depolarise in sequence
Q20. The summation of EPSPs and IPSPs to determine whether a neuron fires takes place mainly at the:✓ Axon hillock (trigger zone)
Q21. Acetylcholine released into the synaptic cleft, after acting on its receptor, is rapidly:✓ Broken down by acetylcholinesterase
Q22. The acetylcholine receptor at the neuromuscular junction is the archetype of a:✓ Ligand-gated ion channel
Q23. Neurotransmitter release from the presynaptic terminal is triggered by the entry of:✓ Calcium ions
Q24. An electrical synapse transmits signals through:✓ Gap junctions allowing direct ion flow
Q25. Compared with a chemical synapse, an electrical synapse has:✓ Almost no synaptic delay
Q26. An inhibitory postsynaptic potential (IPSP) is typically produced by the opening of:✓ Chloride (or potassium) channels
Q27. When several excitatory inputs arrive at different synapses at the same time and add together, this is called:✓ Spatial summation
Q28. Axonal transport of vesicles toward the synaptic terminal (anterograde) is driven by the motor protein:✓ Kinesin
Q29. The neurotransmitter that is the chief excitatory transmitter of the CNS is:✓ Glutamate
6.3 Synaptic Transmission — Test 3
Q30. Glycine acts as an inhibitory neurotransmitter mainly in the:✓ Spinal cord and brainstem
Q31. At a chemical synapse, after the impulse arrives, the sequence of events is:✓ Calcium entry → vesicle fusion → transmitter release → receptor binding
Q32. A metabotropic receptor produces its effect by:✓ Activating a G protein and second messengers
Q33. The synaptic delay (about 0.5 ms) at a chemical synapse is due mainly to the time needed for:✓ Calcium entry and transmitter release
Q34. Spatial and temporal summation of postsynaptic potentials occurs primarily at the:✓ Axon hillock (trigger zone)
Q35. Botulinum toxin causes paralysis by:✓ Blocking acetylcholine release at the neuromuscular junction
Q36. Curare causes muscle paralysis by:✓ Blocking the nicotinic acetylcholine receptors on muscle
Q37. Excitatory postsynaptic potentials (EPSPs) and inhibitory ones (IPSPs) differ in that EPSPs:✓ Depolarise the postsynaptic cell, IPSPs hyperpolarise it
Q38. Saltatory conduction is faster than continuous conduction because the impulse:✓ Jumps between nodes of Ranvier
Q39. After a transmitter such as noradrenaline acts, it is removed mainly by:✓ Reuptake into the presynaptic terminal
Q40. The minimum delay and one-way nature of transmission at chemical synapses ensure that:✓ Signals travel in a single, defined direction
Q41. The structure that stores neurotransmitter in the presynaptic terminal is the:✓ Synaptic vesicle
Q42. A neuromodulator differs from a classical neurotransmitter in that it:✓ Adjusts the strength of synaptic transmission over a longer time
Q43. The convergence of many neurons onto one neuron allows:✓ Integration of many inputs into a single output