Definition of quantal in English:



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

    ‘a quantal release of neurotransmitter’
    • ‘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.’
    • ‘Ideally, this requires the identification of peaks in the histogram at a spacing of one quantal unit.’
    • ‘Expression of tetanus toxin is known to reduce the frequency of spontaneous quantal release.’
    • ‘Although these results do not definitively pinpoint the source of the steps, they confirm the earlier hypothesis that shortening is quantal.’
    • ‘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.’
    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.
      • ‘However the neighboring peaks can merge because of variability of quantal response.’
      • ‘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.’
      • ‘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.’


Early 20th century: from quantum + -al.