Definition of quantal in English:


Pronunciation /ˈkwän(t)l/ /ˈkwɑn(t)l/


  • 1technical Composed of discrete units; varying in steps rather than continuously.

    ‘a quantal release of neurotransmitter’
    • ‘The number of receptors opened following quantal release may vary directly with the total number of receptors at the synapse, but other, more complex, interactions may occur.’
    • ‘Expression of tetanus toxin is known to reduce the frequency of spontaneous quantal release.’
    • ‘Ideally, this requires the identification of peaks in the histogram at a spacing of one quantal unit.’
    • ‘Although these results do not definitively pinpoint the source of the steps, they confirm the earlier hypothesis that shortening is quantal.’
    • ‘The fact that similar step sizes are found in independent experimental approaches using different methodologies implies that the quantal stepping mechanism is a central feature of the contractile process.’
    1. 1.1Physics Relating to a quantum or quanta, or to quantum theory.
      • ‘In this experiment UV + and UV - filters were chosen to yield equal quantal transmittance despite the difference in transmitted wavelengths.’
    2. 1.2Physiology Relating to or denoting an all-or-none response or state.
      ‘Furthermore, it allows one to calculate the apparent quantal size for each response in a sequence of stimuli.’
      • ‘In this case, the quantal amplitude of postsynaptic response strongly depends on the number of accessible postsynaptic receptors in the vicinity of the release sites.’
      • ‘The extrasynaptic receptors that are exposed to a much lower concentration of agonist and are not saturated may substantially enhance the quantal synaptic response.’
      • ‘If the random number was smaller, a release event took place, the site was set to the empty state, and the size of the quantal response was determined as described below.’
      • ‘However the neighboring peaks can merge because of variability of quantal response.’


Early 20th century from quantum+ -al.