OBT Photobiomodulation Mechanisms & Cellular Effects 2 — Questions and Answers
Question 1: Increased nitric oxide (NO) release is one effect of photobiomodulation. What is a primary physiological consequence of elevated NO in treated tissue?
- Vasoconstriction and reduced blood flow
- Vasodilation and improved microcirculation (Correct answer)
- Increased platelet aggregation
- Inhibition of collagen synthesis
Correct answer: Vasodilation and improved microcirculation
Nitric oxide is a potent vasodilator; its release following photobiomodulation promotes vasodilation and enhances local microcirculation, improving oxygen and nutrient delivery.
Question 2: How does photobiomodulation affect the production of pro-inflammatory cytokines such as IL-1β and TNF-α in acute inflammation?
- Significantly increases them to accelerate healing
- Has no measurable effect on cytokine levels
- Modulates them downward, reducing excessive inflammation (Correct answer)
- Converts them to anti-inflammatory forms
Correct answer: Modulates them downward, reducing excessive inflammation
Photobiomodulation downregulates pro-inflammatory cytokines like IL-1β and TNF-α, helping to resolve acute inflammation and transition tissue toward the proliferative healing phase.
Question 3: Which cell type in connective tissue is most directly stimulated by photobiomodulation to increase collagen production?
- Macrophages
- Mast cells
- Fibroblasts (Correct answer)
- Neutrophils
Correct answer: Fibroblasts
Fibroblasts are the primary collagen-producing cells in connective tissue and are directly stimulated by photobiomodulation to proliferate and synthesize collagen, supporting tissue repair.
Question 4: The term 'biphasic dose response' in photobiomodulation refers to:
- Two separate treatment sessions required per week
- Stimulatory effects at low fluences and inhibitory effects at high fluences (Correct answer)
- Dual wavelength protocols using red and near-infrared simultaneously
- Two chromophores being activated in sequence
Correct answer: Stimulatory effects at low fluences and inhibitory effects at high fluences
The biphasic dose response describes how low fluences stimulate cellular activity while excessively high fluences can inhibit or damage cells, making proper dosage calculation critical.
Question 5: Photobiomodulation has been shown to influence neural cells primarily by:
- Permanently destroying damaged neurons
- Enhancing axonal growth and reducing neuroinflammation (Correct answer)
- Blocking all pain signal transmission indefinitely
- Increasing myelin sheath degradation
Correct answer: Enhancing axonal growth and reducing neuroinflammation
Studies demonstrate that photobiomodulation promotes axonal sprouting, regeneration, and reduces neuroinflammation, supporting recovery from peripheral nerve injuries.
Question 6: Which phenomenon describes the light-induced dissociation of nitric oxide from cytochrome c oxidase, proposed as a mechanism that restores mitochondrial function in hypoxic cells?
- Photoelectric effect
- Fluorescence resonance energy transfer (FRET)
- Photodissociation of NO from CCO (Correct answer)
- Laser-induced shockwave
Correct answer: Photodissociation of NO from CCO
Photodissociation of NO from cytochrome c oxidase restores the enzyme's activity in cells where NO has inhibited respiration, a key proposed mechanism for photobiomodulation's mitochondrial benefits.
Question 7: In photobiomodulation research, 'fluence' is the term used to describe:
- The number of photons per second emitted by the device
- The energy delivered per unit area (J/cm²) (Correct answer)
- The frequency of the light wave
- The duration of a single treatment session
Correct answer: The energy delivered per unit area (J/cm²)
Fluence (also called energy density) is expressed in joules per square centimeter (J/cm²) and represents the total light energy delivered to a given tissue area.
OBT Photobiomodulation Mechanisms & Cellular Effects 2
Increased nitric oxide (NO) release is one effect of photobiomodulation.
What is a primary physiological consequence of elevated NO in treated tissue?