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Photobiomodulation Science Flashcards

7 cards from real CLT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Which cellular organelle is the primary chromophore target in photobiomodulation therapy?

    Answer: Mitochondria

    Mitochondria contain cytochrome c oxidase, the primary chromophore that absorbs red and near-infrared light during PBM therapy.

  2. The Arndt-Schulz Law as applied to photobiomodulation states that:

    Answer: Weak stimuli excite, optimal stimuli promote, and excessive stimuli inhibit biological activity

    The Arndt-Schulz Law describes the biphasic dose-response relationship where too little light has no effect and too much light can inhibit or damage tissue.

  3. Which of the following best describes the 'optical window' in PBM therapy?

    Answer: 600–1100 nm range where light penetrates tissue most effectively

    The therapeutic optical window (600–1100 nm) minimizes absorption by water and hemoglobin, allowing deeper tissue penetration.

  4. Retrograde axonal transport of photobiomodulation signals primarily affects which system?

    Answer: Nervous system

    PBM light absorbed by peripheral nerve endings can trigger retrograde signals along axons to cell bodies, affecting neurological function.

  5. What is the role of nitric oxide (NO) in photobiomodulation mechanisms?

    Answer: It is displaced from cytochrome c oxidase, restoring mitochondrial function

    In hypoxic or stressed tissue, NO binds and inhibits cytochrome c oxidase; PBM light displaces this NO, restoring normal electron transport.

  6. Which parameter describes the total energy delivered to tissue during a PBM treatment?

    Answer: Fluence (energy density)

    Fluence (J/cm²) is the total energy delivered per unit area and is the key dosimetric parameter for determining therapeutic effect.

  7. In the context of PBM, what is the significance of the 'coherence' property of laser light?

    Answer: Coherence allows deeper penetration but loses significance in tissue due to scattering

    Laser coherence is lost within millimeters of entering tissue due to scattering, so the biological effects of coherent lasers and LEDs at equivalent doses are similar.