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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. Cytochrome c oxidase (CCO) absorbs light most efficiently in which spectral bands?

    Answer: Red (620–680 nm) and near-infrared (760–830 nm)

    CCO has absorption peaks in the red (~620–680 nm) and near-infrared (~760–830 nm) spectral regions, which correspond to the primary therapeutic wavelengths used in PBM.

  2. What is the role of ATP production in the downstream effects of PBM therapy?

    Answer: Increased ATP provides energy for cellular repair, proliferation, and protein synthesis

    PBM-enhanced mitochondrial ATP production fuels energy-demanding processes like cell proliferation, collagen synthesis, and tissue repair.

  3. Which of the following is an absolute contraindication for PBM therapy?

    Answer: Direct irradiation over a suspected or confirmed malignancy

    Direct PBM application over active malignancies is contraindicated because stimulating cellular metabolism and proliferation could potentially accelerate tumor growth.

  4. The biostimulatory effect of PBM on fibroblasts primarily results in:

    Answer: Increased collagen and extracellular matrix production, accelerating tissue repair

    PBM stimulates fibroblasts to produce more collagen types I and III and other extracellular matrix components, which are essential for wound healing and tissue remodeling.

  5. In pulsed PBM delivery, what does the 'duty cycle' refer to?

    Answer: Percentage of time the laser is 'on' during a pulsed cycle

    Duty cycle is the ratio of 'on' time to total cycle time expressed as a percentage, determining the average power delivered in pulsed mode.

  6. Which wavelength range penetrates deepest into tissue for treating deep musculoskeletal structures?

    Answer: 800–1000 nm (near-infrared)

    Near-infrared wavelengths (800–1000 nm) penetrate deepest within the therapeutic window because they have minimal absorption by melanin, hemoglobin, and water compared to shorter wavelengths.

  7. What is the proposed mechanism by which PBM reduces neural pain signaling?

    Answer: PBM modulates sodium-potassium pump activity and reduces action potential generation in nociceptors

    PBM can hyperpolarize nociceptive neurons by enhancing Na⁺/K⁺-ATPase activity, raising the threshold for action potential firing and reducing pain transmission.