title: Radiation interactions with biological systems.
abstract: The use of radiation, especially ionizing radiation (IR), is currently attracting great attention in the field of medical sciences. However, it should be mentioned that IR has both beneficial and harmful effects in biological systems. This review aims to focus on IR-mediated physiological events in a mechanistic way.
  
  
  
  Evidence from the databases, mainly from PUBMED and SCIENCE DIRECT were considered.
  
  
  
  IR directly and/or with their lyses products (indirect) causes oxidative stresses to biological systems. These activities may be localized and systematic. Otherwise, IR-induced non-/multi-targeted effects are also evident. IR in diagnosis and cancer radiotherapy is well-known. Reactive species produced by IR are not only beneficial, but also can exert harmful effects in a biological system such as aging, genetic instability and mutagenicity, membrane lysis and cell death, alteration of enzymatic activity and metabolic events, mitochondrial dysfunction, and even cancer. Additionally, DNA adducts formation, after IR-induced DNA breakage, is a cause of blockage of DNA repair capability with an increase in cellular radiosensitivity. These may allow cellular ruin even at low IR levels.
  
  
  
  Dependent on the dose, duration of action and quality, IR plays diverse roles in biological systems.
authors.affiliation: a Postgraduate Program in Biotechnology, Northeast Biotechnology Network (RENORBIO) , Federal University of Piauí , Teresina (Paiui) , Brazil.|b Department of Pharmacy , Southern University Bangladesh , Chittagong (Mehedibag) , Bangladesh.
authors.forename: Muhammad Torequl
authors.initials: MT
authors.lastname: Islam
mesh_terms: D000818:Animals; D004249:DNA Damage / Q000502:physiology*; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008954:Models, Biological; D018384:Oxidative Stress / Q000502:physiology* / Q000528:radiation effects*; D011829:Radiation Dosage; D011839:Radiation, Ionizing; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species
keywords: Ionizing radiation; oxidative stress; physiological effects; reactive oxygen species